<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:739a32f6-9240-42e5-8b82-d87631b26e51,g:2742bbb2-cdeb-4d4b-ad9c-00fa3e2b0a64-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.virtu.com/role/CoverPage" xlink:type="simple" xlink:href="virt-20240930.xsd#CoverPage"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/CoverPage" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitiesTable_1d264fcc-acb2-4267-b6ba-d75ad54b8b17" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntitiesTable_1d264fcc-acb2-4267-b6ba-d75ad54b8b17" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_7e1e70de-745e-426e-97f6-73d648090b55" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_EntitiesTable_1d264fcc-acb2-4267-b6ba-d75ad54b8b17" xlink:to="loc_us-gaap_StatementClassOfStockAxis_7e1e70de-745e-426e-97f6-73d648090b55" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_7e1e70de-745e-426e-97f6-73d648090b55_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_7e1e70de-745e-426e-97f6-73d648090b55" xlink:to="loc_us-gaap_ClassOfStockDomain_7e1e70de-745e-426e-97f6-73d648090b55_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_f8827795-642b-418b-8f83-33095af4d256" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_7e1e70de-745e-426e-97f6-73d648090b55" xlink:to="loc_us-gaap_ClassOfStockDomain_f8827795-642b-418b-8f83-33095af4d256" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_6d6f2d77-e008-4e1b-ba0b-e71eef32716e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_f8827795-642b-418b-8f83-33095af4d256" xlink:to="loc_us-gaap_CommonClassAMember_6d6f2d77-e008-4e1b-ba0b-e71eef32716e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassCMember_33daceb6-c706-4cf6-ab85-89252dd1cc9a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_f8827795-642b-418b-8f83-33095af4d256" xlink:to="loc_us-gaap_CommonClassCMember_33daceb6-c706-4cf6-ab85-89252dd1cc9a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_CommonClassDMember_a88c447e-3d57-422e-9de1-2a9b776147fd" xlink:href="virt-20240930.xsd#virt_CommonClassDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_f8827795-642b-418b-8f83-33095af4d256" xlink:to="loc_virt_CommonClassDMember_a88c447e-3d57-422e-9de1-2a9b776147fd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_876d9fc5-e761-42a6-abe1-f75d787a3df2" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_DocumentType_876d9fc5-e761-42a6-abe1-f75d787a3df2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentQuarterlyReport_7b51d70f-0418-4773-8c23-a5266f5dbb2d" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentQuarterlyReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_DocumentQuarterlyReport_7b51d70f-0418-4773-8c23-a5266f5dbb2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_f263f4f4-9e13-470c-b6bc-30aed1c51fcf" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_DocumentPeriodEndDate_f263f4f4-9e13-470c-b6bc-30aed1c51fcf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_5f7a2d49-1e9e-4bae-87d9-6343af398bbb" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentTransitionReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_DocumentTransitionReport_5f7a2d49-1e9e-4bae-87d9-6343af398bbb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_b2a3e320-28ba-4c5d-aa82-84838b864f33" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntityFileNumber_b2a3e320-28ba-4c5d-aa82-84838b864f33" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_7e7d7f26-b072-4da4-b014-98b93cc5625b" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntityRegistrantName_7e7d7f26-b072-4da4-b014-98b93cc5625b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_527e9e3c-d347-48b3-8762-ad506213ba6a" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntityIncorporationStateCountryCode_527e9e3c-d347-48b3-8762-ad506213ba6a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_4c7f297f-03bb-471e-98f9-064d2f79d390" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntityTaxIdentificationNumber_4c7f297f-03bb-471e-98f9-064d2f79d390" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_c2f52d9c-d125-4f9e-9a81-52bb4de981ba" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntityAddressAddressLine1_c2f52d9c-d125-4f9e-9a81-52bb4de981ba" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_92705aca-26a9-46d4-965a-ee411e1b7d47" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntityAddressCityOrTown_92705aca-26a9-46d4-965a-ee411e1b7d47" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_e71edd4c-912b-429e-aa0b-ac145becc5c8" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntityAddressStateOrProvince_e71edd4c-912b-429e-aa0b-ac145becc5c8" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_6e514667-8183-43ea-960b-32980a92ad19" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntityAddressPostalZipCode_6e514667-8183-43ea-960b-32980a92ad19" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_6ab6ba4b-6cf1-41ec-88af-e849966a7ca9" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_CityAreaCode_6ab6ba4b-6cf1-41ec-88af-e849966a7ca9" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_29439ffe-0a26-435b-895e-c194f35c8b9d" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_LocalPhoneNumber_29439ffe-0a26-435b-895e-c194f35c8b9d" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_ec4d0844-52db-4975-8d65-cf55e690e065" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_Security12bTitle_ec4d0844-52db-4975-8d65-cf55e690e065" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_f0ce3325-403b-4e66-846d-18af4b84d562" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_TradingSymbol_f0ce3325-403b-4e66-846d-18af4b84d562" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_ffc875af-7061-4d97-86bd-ac4592889bbb" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_SecurityExchangeName_ffc875af-7061-4d97-86bd-ac4592889bbb" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_002df647-8419-4d9f-adfc-a6fdb11fdff0" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityCurrentReportingStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntityCurrentReportingStatus_002df647-8419-4d9f-adfc-a6fdb11fdff0" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_9b339e7b-7c10-4385-b9d0-161e69933f36" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityInteractiveDataCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntityInteractiveDataCurrent_9b339e7b-7c10-4385-b9d0-161e69933f36" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_9512b94a-9ce9-4cb4-811f-6d041d8813eb" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityFilerCategory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntityFilerCategory_9512b94a-9ce9-4cb4-811f-6d041d8813eb" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness_7c605542-7431-47a1-9cff-7115369e2145" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntitySmallBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntitySmallBusiness_7c605542-7431-47a1-9cff-7115369e2145" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_23d2ef83-97d3-4a6c-9e17-a64c6d6e8768" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntityEmergingGrowthCompany_23d2ef83-97d3-4a6c-9e17-a64c6d6e8768" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_9bb16657-fe85-460d-b22b-260025c79ea2" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityShellCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntityShellCompany_9bb16657-fe85-460d-b22b-260025c79ea2" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_9a583a88-c2e9-46c8-886a-32cffbb7a34e" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityCommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_9a583a88-c2e9-46c8-886a-32cffbb7a34e" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_00591524-dd59-4fd7-9124-e3b7f9248872" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_EntityCentralIndexKey_00591524-dd59-4fd7-9124-e3b7f9248872" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_65d1c49b-22a0-458d-b686-9be6174d436f" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_AmendmentFlag_65d1c49b-22a0-458d-b686-9be6174d436f" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_70bba4a6-cf63-4b3e-976f-5b57558300e1" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentFiscalYearFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_DocumentFiscalYearFocus_70bba4a6-cf63-4b3e-976f-5b57558300e1" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_93a7e82a-e254-4353-947b-8e2f8ddf4321" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentFiscalPeriodFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_DocumentFiscalPeriodFocus_93a7e82a-e254-4353-947b-8e2f8ddf4321" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_3d3a2488-12ba-4275-ac4a-f85ba46160d9" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_CurrentFiscalYearEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_bfefbf56-0c8d-4628-9e1e-9a970aa4d443" xlink:to="loc_dei_CurrentFiscalYearEndDate_3d3a2488-12ba-4275-ac4a-f85ba46160d9" xlink:type="arc" order="28"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/CondensedConsolidatedStatementsofFinancialConditionUnaudited" xlink:type="simple" xlink:href="virt-20240930.xsd#CondensedConsolidatedStatementsofFinancialConditionUnaudited"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/CondensedConsolidatedStatementsofFinancialConditionUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_003e8621-60ed-4407-942e-c8b31a3313b5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_509862c2-9dd6-4eff-b4ce-ce324db644fd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_003e8621-60ed-4407-942e-c8b31a3313b5" xlink:to="loc_us-gaap_StatementTable_509862c2-9dd6-4eff-b4ce-ce324db644fd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusAxis_a840c760-4b94-45b2-8d8c-82335c78b353" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PledgedStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_509862c2-9dd6-4eff-b4ce-ce324db644fd" xlink:to="loc_us-gaap_PledgedStatusAxis_a840c760-4b94-45b2-8d8c-82335c78b353" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusDomain_a840c760-4b94-45b2-8d8c-82335c78b353_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PledgedStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PledgedStatusAxis_a840c760-4b94-45b2-8d8c-82335c78b353" xlink:to="loc_us-gaap_PledgedStatusDomain_a840c760-4b94-45b2-8d8c-82335c78b353_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusDomain_75c28bba-29cb-4c0e-9f74-c3f192f67208" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PledgedStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PledgedStatusAxis_a840c760-4b94-45b2-8d8c-82335c78b353" xlink:to="loc_us-gaap_PledgedStatusDomain_75c28bba-29cb-4c0e-9f74-c3f192f67208" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetNotPledgedAsCollateralMember_1d703d78-2066-4bef-8de0-dead88c039c6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetNotPledgedAsCollateralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PledgedStatusDomain_75c28bba-29cb-4c0e-9f74-c3f192f67208" xlink:to="loc_us-gaap_AssetNotPledgedAsCollateralMember_1d703d78-2066-4bef-8de0-dead88c039c6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetPledgedAsCollateralMember_299b0af0-9f7d-4778-a452-9d6ac0cf0eed" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetPledgedAsCollateralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PledgedStatusDomain_75c28bba-29cb-4c0e-9f74-c3f192f67208" xlink:to="loc_us-gaap_AssetPledgedAsCollateralMember_299b0af0-9f7d-4778-a452-9d6ac0cf0eed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_29d36598-3d4f-49ee-bc8d-38332ffa2117" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_509862c2-9dd6-4eff-b4ce-ce324db644fd" xlink:to="loc_us-gaap_StatementClassOfStockAxis_29d36598-3d4f-49ee-bc8d-38332ffa2117" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_29d36598-3d4f-49ee-bc8d-38332ffa2117_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_29d36598-3d4f-49ee-bc8d-38332ffa2117" xlink:to="loc_us-gaap_ClassOfStockDomain_29d36598-3d4f-49ee-bc8d-38332ffa2117_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_5a002e8a-8091-472f-a347-b7cedfa39b37" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_29d36598-3d4f-49ee-bc8d-38332ffa2117" xlink:to="loc_us-gaap_ClassOfStockDomain_5a002e8a-8091-472f-a347-b7cedfa39b37" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_304be2e8-ed31-475e-aae1-cffa0cc3458d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5a002e8a-8091-472f-a347-b7cedfa39b37" xlink:to="loc_us-gaap_CommonClassAMember_304be2e8-ed31-475e-aae1-cffa0cc3458d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_0a2831c3-ecd7-4538-8d6b-33b2c6b467dd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5a002e8a-8091-472f-a347-b7cedfa39b37" xlink:to="loc_us-gaap_CommonClassBMember_0a2831c3-ecd7-4538-8d6b-33b2c6b467dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassCMember_4bd259fa-5938-4346-8a5d-084b0209d1b9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5a002e8a-8091-472f-a347-b7cedfa39b37" xlink:to="loc_us-gaap_CommonClassCMember_4bd259fa-5938-4346-8a5d-084b0209d1b9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_CommonClassDMember_81441d1b-3188-4e61-ad04-5322ae0bd33a" xlink:href="virt-20240930.xsd#virt_CommonClassDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5a002e8a-8091-472f-a347-b7cedfa39b37" xlink:to="loc_virt_CommonClassDMember_81441d1b-3188-4e61-ad04-5322ae0bd33a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_003e8621-60ed-4407-942e-c8b31a3313b5" xlink:to="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_95b9c357-5a3d-4d65-b42c-8bbc55aa2f8c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_95b9c357-5a3d-4d65-b42c-8bbc55aa2f8c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCash_7e9001ca-20f7-4526-9c99-bf55215172c8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:to="loc_us-gaap_RestrictedCash_7e9001ca-20f7-4526-9c99-bf55215172c8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesBorrowed_c1b4e023-f788-41a8-827c-2965fac5a2b8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesBorrowed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:to="loc_us-gaap_SecuritiesBorrowed_c1b4e023-f788-41a8-827c-2965fac5a2b8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResell_e2825752-5c75-4f5c-a96c-7b88197e3f48" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesPurchasedUnderAgreementsToResell"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:to="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResell_e2825752-5c75-4f5c-a96c-7b88197e3f48" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations_2fb103c5-6e23-494a-9e0f-fb01dae2a19f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:to="loc_us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations_2fb103c5-6e23-494a-9e0f-fb01dae2a19f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentsOwnedAtFairValueByTypeAbstract_8e64e84c-aeac-4a25-ac4a-e71d91adbbd9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentsOwnedAtFairValueByTypeAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:to="loc_us-gaap_FinancialInstrumentsOwnedAtFairValueByTypeAbstract_8e64e84c-aeac-4a25-ac4a-e71d91adbbd9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentsOwnedAtFairValue_c750f604-303a-41f0-b0bf-99e1b1f24c26" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentsOwnedAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsOwnedAtFairValueByTypeAbstract_8e64e84c-aeac-4a25-ac4a-e71d91adbbd9" xlink:to="loc_us-gaap_FinancialInstrumentsOwnedAtFairValue_c750f604-303a-41f0-b0bf-99e1b1f24c26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesFromCustomers_9a86352b-6266-4204-99fd-5defc0f225ea" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReceivablesFromCustomers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:to="loc_us-gaap_ReceivablesFromCustomers_9a86352b-6266-4204-99fd-5defc0f225ea" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_a6992699-290a-483d-8555-7905c60ad2e1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_a6992699-290a-483d-8555-7905c60ad2e1" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_8e630efa-a092-4194-bbb7-05af82bc735d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_8e630efa-a092-4194-bbb7-05af82bc735d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_956b059c-5463-4536-8faa-709d4566f4d0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:to="loc_us-gaap_Goodwill_956b059c-5463-4536-8faa-709d4566f4d0" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_471eef54-a714-4b74-9466-976308f61d8a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_471eef54-a714-4b74-9466-976308f61d8a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_3a6fe21a-5ae2-433c-8320-808b2c67eb3c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_3a6fe21a-5ae2-433c-8320-808b2c67eb3c" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation_12241184-931e-443e-961e-edad3ab0605f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation_12241184-931e-443e-961e-edad3ab0605f" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssets_3896f7b3-72dc-48f7-8c4f-33aa0027c402" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:to="loc_us-gaap_OtherAssets_3896f7b3-72dc-48f7-8c4f-33aa0027c402" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_fce2c46a-53e7-477a-8150-3b29b7245ecb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2cd7156a-136e-450a-8f0d-48ae05288965" xlink:to="loc_us-gaap_Assets_fce2c46a-53e7-477a-8150-3b29b7245ecb" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_a5ca46e9-62e6-4ed9-b31d-1f2c8e55f2d6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_003e8621-60ed-4407-942e-c8b31a3313b5" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_a5ca46e9-62e6-4ed9-b31d-1f2c8e55f2d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAbstract_66684ec3-3a06-4338-b05a-761775e90c99" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_a5ca46e9-62e6-4ed9-b31d-1f2c8e55f2d6" xlink:to="loc_us-gaap_LiabilitiesAbstract_66684ec3-3a06-4338-b05a-761775e90c99" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherShortTermBorrowings_ec176228-1551-4ed4-9784-d8965e1cfd21" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherShortTermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_66684ec3-3a06-4338-b05a-761775e90c99" xlink:to="loc_us-gaap_OtherShortTermBorrowings_ec176228-1551-4ed4-9784-d8965e1cfd21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesLoaned_83573f72-9a86-492a-82b9-1b2f916cf287" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesLoaned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_66684ec3-3a06-4338-b05a-761775e90c99" xlink:to="loc_us-gaap_SecuritiesLoaned_83573f72-9a86-492a-82b9-1b2f916cf287" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchase_658817b7-4992-4b1e-b3cd-dd537d417cca" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesSoldUnderAgreementsToRepurchase"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_66684ec3-3a06-4338-b05a-761775e90c99" xlink:to="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchase_658817b7-4992-4b1e-b3cd-dd537d417cca" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_PayablesToBrokerDealersAndClearingOrganizations_9969b1f6-ea4a-481d-99aa-bb29d8c2df12" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_PayablesToBrokerDealersAndClearingOrganizations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_66684ec3-3a06-4338-b05a-761775e90c99" xlink:to="loc_srt_PayablesToBrokerDealersAndClearingOrganizations_9969b1f6-ea4a-481d-99aa-bb29d8c2df12" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_PayablesToCustomers_29dcc512-852b-4842-ad8f-8e13e25f0235" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_PayablesToCustomers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_66684ec3-3a06-4338-b05a-761775e90c99" xlink:to="loc_srt_PayablesToCustomers_29dcc512-852b-4842-ad8f-8e13e25f0235" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentsSoldNotYetPurchasedAtFairValueAbstract_cfdf1714-6017-43eb-939b-2eb1af025f47" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentsSoldNotYetPurchasedAtFairValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_66684ec3-3a06-4338-b05a-761775e90c99" xlink:to="loc_us-gaap_FinancialInstrumentsSoldNotYetPurchasedAtFairValueAbstract_cfdf1714-6017-43eb-939b-2eb1af025f47" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentsSoldNotYetPurchasedAtFairValue_ca14f3aa-6230-4aff-9161-1d00ee99ccc7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentsSoldNotYetPurchasedAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsSoldNotYetPurchasedAtFairValueAbstract_cfdf1714-6017-43eb-939b-2eb1af025f47" xlink:to="loc_us-gaap_FinancialInstrumentsSoldNotYetPurchasedAtFairValue_ca14f3aa-6230-4aff-9161-1d00ee99ccc7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_TaxReceivableAgreementObligations_5ad978c7-abd1-4467-84f2-840546b0c35a" xlink:href="virt-20240930.xsd#virt_TaxReceivableAgreementObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_66684ec3-3a06-4338-b05a-761775e90c99" xlink:to="loc_virt_TaxReceivableAgreementObligations_5ad978c7-abd1-4467-84f2-840546b0c35a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_AccountsPayableAccruedExpensesAndOtherLiabilities_50c334aa-763e-4158-9dae-88528dc24a70" xlink:href="virt-20240930.xsd#virt_AccountsPayableAccruedExpensesAndOtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_66684ec3-3a06-4338-b05a-761775e90c99" xlink:to="loc_virt_AccountsPayableAccruedExpensesAndOtherLiabilities_50c334aa-763e-4158-9dae-88528dc24a70" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_368dda28-9862-435a-b540-a8edbb07216a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_66684ec3-3a06-4338-b05a-761775e90c99" xlink:to="loc_us-gaap_OperatingLeaseLiability_368dda28-9862-435a-b540-a8edbb07216a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_822f6cb1-2558-4519-8942-e8d1647cf160" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_66684ec3-3a06-4338-b05a-761775e90c99" xlink:to="loc_us-gaap_LongTermDebt_822f6cb1-2558-4519-8942-e8d1647cf160" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_2419998b-8b27-4242-a48a-9132b2f1a098" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_66684ec3-3a06-4338-b05a-761775e90c99" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_2419998b-8b27-4242-a48a-9132b2f1a098" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_0ff27cf2-22ea-4cb5-baaa-9f60b7721ce4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_66684ec3-3a06-4338-b05a-761775e90c99" xlink:to="loc_us-gaap_Liabilities_0ff27cf2-22ea-4cb5-baaa-9f60b7721ce4" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_bd4c2f22-a28e-452e-adac-1d0217a993a4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_a5ca46e9-62e6-4ed9-b31d-1f2c8e55f2d6" xlink:to="loc_us-gaap_CommitmentsAndContingencies_bd4c2f22-a28e-452e-adac-1d0217a993a4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_c00edada-9525-4d34-9910-c77d6a646e56" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_a5ca46e9-62e6-4ed9-b31d-1f2c8e55f2d6" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_c00edada-9525-4d34-9910-c77d6a646e56" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_b5a5787f-b88d-460c-b37e-230d5bdf758a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_c00edada-9525-4d34-9910-c77d6a646e56" xlink:to="loc_us-gaap_CommonStockValue_b5a5787f-b88d-460c-b37e-230d5bdf758a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonValue_394a89f1-2a07-4119-ae14-89752af05778" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockCommonValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_c00edada-9525-4d34-9910-c77d6a646e56" xlink:to="loc_us-gaap_TreasuryStockCommonValue_394a89f1-2a07-4119-ae14-89752af05778" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_d0634c19-60ad-4c2a-8ca9-f59859b33c42" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_c00edada-9525-4d34-9910-c77d6a646e56" xlink:to="loc_us-gaap_AdditionalPaidInCapital_d0634c19-60ad-4c2a-8ca9-f59859b33c42" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_d384361a-25f4-4555-8eaf-561c9c047e10" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_c00edada-9525-4d34-9910-c77d6a646e56" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_d384361a-25f4-4555-8eaf-561c9c047e10" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_d5b487ad-f89c-45ca-b1de-4e4cae181e92" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_c00edada-9525-4d34-9910-c77d6a646e56" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_d5b487ad-f89c-45ca-b1de-4e4cae181e92" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_49c2d6fe-7dfe-46c9-8c72-53178f4c7605" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_c00edada-9525-4d34-9910-c77d6a646e56" xlink:to="loc_us-gaap_StockholdersEquity_49c2d6fe-7dfe-46c9-8c72-53178f4c7605" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterest_afe8580a-683c-4595-a245-c3d9b74bfaeb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MinorityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_c00edada-9525-4d34-9910-c77d6a646e56" xlink:to="loc_us-gaap_MinorityInterest_afe8580a-683c-4595-a245-c3d9b74bfaeb" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_b33d3434-938a-4a1b-80d2-c2d8dcda7130" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_c00edada-9525-4d34-9910-c77d6a646e56" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_b33d3434-938a-4a1b-80d2-c2d8dcda7130" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_e73395cb-4dd2-481d-bd2d-7ca1514b491e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_a5ca46e9-62e6-4ed9-b31d-1f2c8e55f2d6" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_e73395cb-4dd2-481d-bd2d-7ca1514b491e" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/CondensedConsolidatedStatementsofFinancialConditionUnauditedParenthetical" xlink:type="simple" xlink:href="virt-20240930.xsd#CondensedConsolidatedStatementsofFinancialConditionUnauditedParenthetical"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/CondensedConsolidatedStatementsofFinancialConditionUnauditedParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_dcd48bec-52dd-4b9e-86a9-ba4520d86bf1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_b9818765-db6b-4c8e-a6b0-f17f3373bcab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_dcd48bec-52dd-4b9e-86a9-ba4520d86bf1" xlink:to="loc_us-gaap_StatementTable_b9818765-db6b-4c8e-a6b0-f17f3373bcab" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_fe4d481b-7d39-4bd4-b3d7-4fd05287ea30" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_b9818765-db6b-4c8e-a6b0-f17f3373bcab" xlink:to="loc_us-gaap_StatementClassOfStockAxis_fe4d481b-7d39-4bd4-b3d7-4fd05287ea30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_fe4d481b-7d39-4bd4-b3d7-4fd05287ea30_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_fe4d481b-7d39-4bd4-b3d7-4fd05287ea30" xlink:to="loc_us-gaap_ClassOfStockDomain_fe4d481b-7d39-4bd4-b3d7-4fd05287ea30_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_8b0af39e-9255-495b-9d97-a6b2d3daa7f5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_fe4d481b-7d39-4bd4-b3d7-4fd05287ea30" xlink:to="loc_us-gaap_ClassOfStockDomain_8b0af39e-9255-495b-9d97-a6b2d3daa7f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_9a986924-47bb-4363-8e3e-728c56233fa3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_8b0af39e-9255-495b-9d97-a6b2d3daa7f5" xlink:to="loc_us-gaap_CommonClassAMember_9a986924-47bb-4363-8e3e-728c56233fa3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_c104b769-9133-43c2-abd3-9d3bd563d25d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_8b0af39e-9255-495b-9d97-a6b2d3daa7f5" xlink:to="loc_us-gaap_CommonClassBMember_c104b769-9133-43c2-abd3-9d3bd563d25d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassCMember_be8e0dca-353a-425a-bbb0-5529820867f3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_8b0af39e-9255-495b-9d97-a6b2d3daa7f5" xlink:to="loc_us-gaap_CommonClassCMember_be8e0dca-353a-425a-bbb0-5529820867f3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_CommonClassDMember_719bb7b6-e836-41fe-93ab-97791d0e2956" xlink:href="virt-20240930.xsd#virt_CommonClassDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_8b0af39e-9255-495b-9d97-a6b2d3daa7f5" xlink:to="loc_virt_CommonClassDMember_719bb7b6-e836-41fe-93ab-97791d0e2956" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_3dfa206b-5a97-481f-8b13-2230da3c14cb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_b9818765-db6b-4c8e-a6b0-f17f3373bcab" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_3dfa206b-5a97-481f-8b13-2230da3c14cb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_3dfa206b-5a97-481f-8b13-2230da3c14cb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_3dfa206b-5a97-481f-8b13-2230da3c14cb" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_3dfa206b-5a97-481f-8b13-2230da3c14cb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_f4acebdb-8d6c-4338-9bc0-acfd0e806425" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_3dfa206b-5a97-481f-8b13-2230da3c14cb" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_f4acebdb-8d6c-4338-9bc0-acfd0e806425" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_a5d5a0eb-bd32-41e4-8f74-12d5266486ab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_f4acebdb-8d6c-4338-9bc0-acfd0e806425" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_a5d5a0eb-bd32-41e4-8f74-12d5266486ab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_2bd6f284-8f82-4c81-bdca-80a7d696f4af" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_f4acebdb-8d6c-4338-9bc0-acfd0e806425" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_2bd6f284-8f82-4c81-bdca-80a7d696f4af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_30cf4093-112c-42f4-95aa-8f5a5b7ae445" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_b9818765-db6b-4c8e-a6b0-f17f3373bcab" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_30cf4093-112c-42f4-95aa-8f5a5b7ae445" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_30cf4093-112c-42f4-95aa-8f5a5b7ae445_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_30cf4093-112c-42f4-95aa-8f5a5b7ae445" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_30cf4093-112c-42f4-95aa-8f5a5b7ae445_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_e514984f-5471-4ad1-9b49-642ab85e0c97" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_30cf4093-112c-42f4-95aa-8f5a5b7ae445" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_e514984f-5471-4ad1-9b49-642ab85e0c97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_6a55b01a-6f67-4f9b-9a49-9c79ed5211c9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_e514984f-5471-4ad1-9b49-642ab85e0c97" xlink:to="loc_us-gaap_InterestRateSwapMember_6a55b01a-6f67-4f9b-9a49-9c79ed5211c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations_e891e49c-a765-491b-80ee-52f64882fd28" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_dcd48bec-52dd-4b9e-86a9-ba4520d86bf1" xlink:to="loc_us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations_e891e49c-a765-491b-80ee-52f64882fd28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_cec9e6d0-f79b-4e38-88eb-a1d1cba3bef2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_dcd48bec-52dd-4b9e-86a9-ba4520d86bf1" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_cec9e6d0-f79b-4e38-88eb-a1d1cba3bef2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_a20b33ae-b15d-422e-8bb3-3f74b0c2c5a7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_dcd48bec-52dd-4b9e-86a9-ba4520d86bf1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_a20b33ae-b15d-422e-8bb3-3f74b0c2c5a7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsFairValueDisclosure_9393c4b9-86e5-4056-9545-f1a65f146b74" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherAssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_dcd48bec-52dd-4b9e-86a9-ba4520d86bf1" xlink:to="loc_us-gaap_OtherAssetsFairValueDisclosure_9393c4b9-86e5-4056-9545-f1a65f146b74" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_PayablesToBrokerDealersAndClearingOrganizations_51862382-a9fb-4cb5-8289-42c4fa6859b4" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_PayablesToBrokerDealersAndClearingOrganizations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_dcd48bec-52dd-4b9e-86a9-ba4520d86bf1" xlink:to="loc_srt_PayablesToBrokerDealersAndClearingOrganizations_51862382-a9fb-4cb5-8289-42c4fa6859b4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_61178f32-da42-4855-870f-37cdfe6ffba5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_dcd48bec-52dd-4b9e-86a9-ba4520d86bf1" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_61178f32-da42-4855-870f-37cdfe6ffba5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_dcc081f1-fd0a-4bd3-8965-d58dd607b5cd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_dcd48bec-52dd-4b9e-86a9-ba4520d86bf1" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_dcc081f1-fd0a-4bd3-8965-d58dd607b5cd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_3f6ab4c9-cb5f-4258-870a-59fa50a813ac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_dcd48bec-52dd-4b9e-86a9-ba4520d86bf1" xlink:to="loc_us-gaap_CommonStockSharesIssued_3f6ab4c9-cb5f-4258-870a-59fa50a813ac" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_488ad052-e76c-4375-80ac-3de024eb9b46" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_dcd48bec-52dd-4b9e-86a9-ba4520d86bf1" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_488ad052-e76c-4375-80ac-3de024eb9b46" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_59c0af00-8180-437d-95aa-2fc07e5d4a3c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_dcd48bec-52dd-4b9e-86a9-ba4520d86bf1" xlink:to="loc_us-gaap_TreasuryStockCommonShares_59c0af00-8180-437d-95aa-2fc07e5d4a3c" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/CondensedConsolidatedStatementsofChangesinEquityUnaudited" xlink:type="simple" xlink:href="virt-20240930.xsd#CondensedConsolidatedStatementsofChangesinEquityUnaudited"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/CondensedConsolidatedStatementsofChangesinEquityUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_da067afa-ef74-47ca-9f59-25ec35cf458c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_c124dd05-841c-4880-abae-d1f0fe523fb5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_da067afa-ef74-47ca-9f59-25ec35cf458c" xlink:to="loc_us-gaap_StatementTable_c124dd05-841c-4880-abae-d1f0fe523fb5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_5fc10f90-c1f7-4ebb-9742-8131177cd125" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_c124dd05-841c-4880-abae-d1f0fe523fb5" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_5fc10f90-c1f7-4ebb-9742-8131177cd125" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_5fc10f90-c1f7-4ebb-9742-8131177cd125_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_5fc10f90-c1f7-4ebb-9742-8131177cd125" xlink:to="loc_us-gaap_EquityComponentDomain_5fc10f90-c1f7-4ebb-9742-8131177cd125_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_0d8c6ae9-a598-4259-9a2b-e5a4b62908ba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_5fc10f90-c1f7-4ebb-9742-8131177cd125" xlink:to="loc_us-gaap_EquityComponentDomain_0d8c6ae9-a598-4259-9a2b-e5a4b62908ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParentMember_c50a07f9-5be3-4f2e-9da1-c73264bcefb7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0d8c6ae9-a598-4259-9a2b-e5a4b62908ba" xlink:to="loc_us-gaap_ParentMember_c50a07f9-5be3-4f2e-9da1-c73264bcefb7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_c03b2235-0d59-4504-825c-74e751d22d4a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_c50a07f9-5be3-4f2e-9da1-c73264bcefb7" xlink:to="loc_us-gaap_CommonStockMember_c03b2235-0d59-4504-825c-74e751d22d4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_f0fe9d35-b56e-4fe7-8ca9-f765dfb2606c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_c50a07f9-5be3-4f2e-9da1-c73264bcefb7" xlink:to="loc_us-gaap_TreasuryStockCommonMember_f0fe9d35-b56e-4fe7-8ca9-f765dfb2606c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_13dd341b-02f4-4445-b676-1edd027a05ba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_c50a07f9-5be3-4f2e-9da1-c73264bcefb7" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_13dd341b-02f4-4445-b676-1edd027a05ba" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_5f4d0835-e358-4cb5-936a-2c3a951c3354" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_c50a07f9-5be3-4f2e-9da1-c73264bcefb7" xlink:to="loc_us-gaap_RetainedEarningsMember_5f4d0835-e358-4cb5-936a-2c3a951c3354" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AociIncludingPortionAttributableToNoncontrollingInterestMember_716d1921-833b-41cd-8226-cadb4f82cd02" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AociIncludingPortionAttributableToNoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_c50a07f9-5be3-4f2e-9da1-c73264bcefb7" xlink:to="loc_us-gaap_AociIncludingPortionAttributableToNoncontrollingInterestMember_716d1921-833b-41cd-8226-cadb4f82cd02" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_bc3d6cf0-d860-47fb-ba7a-d7c943fb0f20" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0d8c6ae9-a598-4259-9a2b-e5a4b62908ba" xlink:to="loc_us-gaap_NoncontrollingInterestMember_bc3d6cf0-d860-47fb-ba7a-d7c943fb0f20" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_9992e27f-7f85-40c1-8c9a-9dffaa7a719f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_c124dd05-841c-4880-abae-d1f0fe523fb5" xlink:to="loc_us-gaap_StatementClassOfStockAxis_9992e27f-7f85-40c1-8c9a-9dffaa7a719f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_9992e27f-7f85-40c1-8c9a-9dffaa7a719f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_9992e27f-7f85-40c1-8c9a-9dffaa7a719f" xlink:to="loc_us-gaap_ClassOfStockDomain_9992e27f-7f85-40c1-8c9a-9dffaa7a719f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_4af36751-bde4-47a8-a6b4-9d78a9b6999d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_9992e27f-7f85-40c1-8c9a-9dffaa7a719f" xlink:to="loc_us-gaap_ClassOfStockDomain_4af36751-bde4-47a8-a6b4-9d78a9b6999d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_ef14f948-c429-439e-84a2-ea0e8cb5b37a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_4af36751-bde4-47a8-a6b4-9d78a9b6999d" xlink:to="loc_us-gaap_CommonClassAMember_ef14f948-c429-439e-84a2-ea0e8cb5b37a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassCMember_cb3da7b2-cff7-420d-b0a2-5a175b157bc6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_4af36751-bde4-47a8-a6b4-9d78a9b6999d" xlink:to="loc_us-gaap_CommonClassCMember_cb3da7b2-cff7-420d-b0a2-5a175b157bc6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_CommonClassDMember_4c58a64e-c642-4858-ba61-ce16ffe9e045" xlink:href="virt-20240930.xsd#virt_CommonClassDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_4af36751-bde4-47a8-a6b4-9d78a9b6999d" xlink:to="loc_virt_CommonClassDMember_4c58a64e-c642-4858-ba61-ce16ffe9e045" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_da067afa-ef74-47ca-9f59-25ec35cf458c" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_340cde3f-9de3-408f-b2c7-364a32f44152" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_340cde3f-9de3-408f-b2c7-364a32f44152" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_6f031cdb-0796-4752-813e-c18ba72e856b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_6f031cdb-0796-4752-813e-c18ba72e856b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_9b2a694f-a474-4625-9da2-7898bd8bc08e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_us-gaap_TreasuryStockCommonShares_9b2a694f-a474-4625-9da2-7898bd8bc08e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_61f2b564-74c8-45d4-a5b3-3e11337cc9c2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_61f2b564-74c8-45d4-a5b3-3e11337cc9c2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_a9664b5e-d39c-4261-95f3-8681631e143f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_a9664b5e-d39c-4261-95f3-8681631e143f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_fc259667-0fbc-4ec6-bd88-eb7a8c3d71ba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_fc259667-0fbc-4ec6-bd88-eb7a8c3d71ba" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_79fe5d8e-4f1e-421f-bfcf-ef9c4db71d1e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_79fe5d8e-4f1e-421f-bfcf-ef9c4db71d1e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_fa7673b3-c88e-4812-ba40-b87d947941bd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_fa7673b3-c88e-4812-ba40-b87d947941bd" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_7efa34de-dfe5-4188-9a8b-8a828c898382" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_7efa34de-dfe5-4188-9a8b-8a828c898382" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_518a57e5-ed9a-43cd-bf87-f8c2ae964b0c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_518a57e5-ed9a-43cd-bf87-f8c2ae964b0c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_a8b6b37a-df60-430b-a018-3ff188993582" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_a8b6b37a-df60-430b-a018-3ff188993582" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_52014ade-30be-419b-93d6-6f462c433ec4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_us-gaap_ProfitLoss_52014ade-30be-419b-93d6-6f462c433ec4" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_afd393fa-bd8d-4786-abcd-75aef7fac048" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_afd393fa-bd8d-4786-abcd-75aef7fac048" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax_77d39433-bf8a-4a8d-ad09-a447e7debe04" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax_77d39433-bf8a-4a8d-ad09-a447e7debe04" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStock_b5366ce9-5643-4643-aaef-3292ff0262be" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DividendsCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_us-gaap_DividendsCommonStock_b5366ce9-5643-4643-aaef-3292ff0262be" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_StockIssuedDuringPeriodSharesEmployeeExchanges_98a04f86-5702-4b07-8afa-cb3c79443a9c" xlink:href="virt-20240930.xsd#virt_StockIssuedDuringPeriodSharesEmployeeExchanges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_virt_StockIssuedDuringPeriodSharesEmployeeExchanges_98a04f86-5702-4b07-8afa-cb3c79443a9c" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_CommonUnitsRepurchasedDuringPeriodInSecondaryOfferingShares_cf6d0969-21ed-4e61-94ab-e373037439d7" xlink:href="virt-20240930.xsd#virt_CommonUnitsRepurchasedDuringPeriodInSecondaryOfferingShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_virt_CommonUnitsRepurchasedDuringPeriodInSecondaryOfferingShares_cf6d0969-21ed-4e61-94ab-e373037439d7" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_AdjustmentsToAdditionalPaidInCapitalSharesIncreaseDecreaseInTaxReceivableAgreement_2c69006e-bf1b-441e-8824-6d2d7283d333" xlink:href="virt-20240930.xsd#virt_AdjustmentsToAdditionalPaidInCapitalSharesIncreaseDecreaseInTaxReceivableAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_virt_AdjustmentsToAdditionalPaidInCapitalSharesIncreaseDecreaseInTaxReceivableAgreement_2c69006e-bf1b-441e-8824-6d2d7283d333" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_AdjustmentsToAdditionalPaidInCapitalIncreaseDecreaseInTaxReceivableAgreement_ac8b9190-c210-420a-a784-ed2f5b390cae" xlink:href="virt-20240930.xsd#virt_AdjustmentsToAdditionalPaidInCapitalIncreaseDecreaseInTaxReceivableAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_006e1239-84a1-44e1-bace-f00a99b62dc2" xlink:to="loc_virt_AdjustmentsToAdditionalPaidInCapitalIncreaseDecreaseInTaxReceivableAgreement_ac8b9190-c210-420a-a784-ed2f5b390cae" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_124e933c-6f3d-495c-8ece-bf7e3c97e3f0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_9016dd14-d556-4a53-a6d0-a3fb35c65a45" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_e1f7339b-839d-4b26-9444-ef0d9a4b1333" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockCommonShares"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/OrganizationandBasisofPresentationDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#OrganizationandBasisofPresentationDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/OrganizationandBasisofPresentationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_virt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_e8b94c92-22a9-40a4-afdf-16017d6ba5b3" xlink:href="virt-20240930.xsd#virt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_0462fcb7-03f1-4259-8509-5d9b4046b193" xlink:href="virt-20240930.xsd#virt_OrganizationConsolidationAndPresentationOfFinancialStatementsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_virt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_e8b94c92-22a9-40a4-afdf-16017d6ba5b3" xlink:to="loc_virt_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_0462fcb7-03f1-4259-8509-5d9b4046b193" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_770b079c-da72-40bf-b8e8-8a8300e4e9fe" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_virt_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_0462fcb7-03f1-4259-8509-5d9b4046b193" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_770b079c-da72-40bf-b8e8-8a8300e4e9fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_770b079c-da72-40bf-b8e8-8a8300e4e9fe_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_770b079c-da72-40bf-b8e8-8a8300e4e9fe" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_770b079c-da72-40bf-b8e8-8a8300e4e9fe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_fd061d68-633c-4b38-a651-eab3f1867b9f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_770b079c-da72-40bf-b8e8-8a8300e4e9fe" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_fd061d68-633c-4b38-a651-eab3f1867b9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuFinancialLlcMember_55387439-3817-4534-a0f6-5dcbbbe9e003" xlink:href="virt-20240930.xsd#virt_VirtuFinancialLlcMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_fd061d68-633c-4b38-a651-eab3f1867b9f" xlink:to="loc_virt_VirtuFinancialLlcMember_55387439-3817-4534-a0f6-5dcbbbe9e003" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_14924851-2129-480d-82a1-09e1f18b3c71" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_virt_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_0462fcb7-03f1-4259-8509-5d9b4046b193" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_14924851-2129-480d-82a1-09e1f18b3c71" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_14924851-2129-480d-82a1-09e1f18b3c71_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_14924851-2129-480d-82a1-09e1f18b3c71" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_14924851-2129-480d-82a1-09e1f18b3c71_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_207c7f95-7974-4520-9bbc-3bc22b65654d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_14924851-2129-480d-82a1-09e1f18b3c71" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_207c7f95-7974-4520-9bbc-3bc22b65654d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_28c6fd59-0135-4dd5-a3f7-d0d722f16022" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_207c7f95-7974-4520-9bbc-3bc22b65654d" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_28c6fd59-0135-4dd5-a3f7-d0d722f16022" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_de775f48-b24b-4491-a448-05c855288d27" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_virt_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_0462fcb7-03f1-4259-8509-5d9b4046b193" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_de775f48-b24b-4491-a448-05c855288d27" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_de775f48-b24b-4491-a448-05c855288d27_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_de775f48-b24b-4491-a448-05c855288d27" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_de775f48-b24b-4491-a448-05c855288d27_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_be495604-3602-4df8-a099-873de7927afa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_de775f48-b24b-4491-a448-05c855288d27" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_be495604-3602-4df8-a099-873de7927afa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RFQHubMember_974a48b6-3c52-4910-a18a-59f04081c578" xlink:href="virt-20240930.xsd#virt_RFQHubMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_be495604-3602-4df8-a099-873de7927afa" xlink:to="loc_virt_RFQHubMember_974a48b6-3c52-4910-a18a-59f04081c578" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_065afe22-dd26-4e9d-a3fa-b031a9ea8b31" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_e8b94c92-22a9-40a4-afdf-16017d6ba5b3" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_065afe22-dd26-4e9d-a3fa-b031a9ea8b31" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_EntityNumberOfFinancialInstruments_a1103712-2cbb-46c0-bc0b-7c978faff5af" xlink:href="virt-20240930.xsd#virt_EntityNumberOfFinancialInstruments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_e8b94c92-22a9-40a4-afdf-16017d6ba5b3" xlink:to="loc_virt_EntityNumberOfFinancialInstruments_a1103712-2cbb-46c0-bc0b-7c978faff5af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_EntityNumberOfVenues_3f638778-edf3-4e2e-b8bd-13e81503a292" xlink:href="virt-20240930.xsd#virt_EntityNumberOfVenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_e8b94c92-22a9-40a4-afdf-16017d6ba5b3" xlink:to="loc_virt_EntityNumberOfVenues_3f638778-edf3-4e2e-b8bd-13e81503a292" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfCountriesInWhichEntityOperates_eb8bff2e-ed07-4c84-a63d-d6aea416b339" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NumberOfCountriesInWhichEntityOperates"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_e8b94c92-22a9-40a4-afdf-16017d6ba5b3" xlink:to="loc_us-gaap_NumberOfCountriesInWhichEntityOperates_eb8bff2e-ed07-4c84-a63d-d6aea416b339" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_CompanyProductOfferingsAllowingClientsToTradeNumberOfCountries_3484653f-664e-4d99-b6be-cdd2ee3f0616" xlink:href="virt-20240930.xsd#virt_CompanyProductOfferingsAllowingClientsToTradeNumberOfCountries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_e8b94c92-22a9-40a4-afdf-16017d6ba5b3" xlink:to="loc_virt_CompanyProductOfferingsAllowingClientsToTradeNumberOfCountries_3484653f-664e-4d99-b6be-cdd2ee3f0616" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_NumberOfSignificantAcquisitions_e7dd480c-d5d2-48a8-bc62-408a7776e3a3" xlink:href="virt-20240930.xsd#virt_NumberOfSignificantAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_e8b94c92-22a9-40a4-afdf-16017d6ba5b3" xlink:to="loc_virt_NumberOfSignificantAcquisitions_e7dd480c-d5d2-48a8-bc62-408a7776e3a3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_8e72fdfe-176b-4b78-bb21-71fe670790f7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_e8b94c92-22a9-40a4-afdf-16017d6ba5b3" xlink:to="loc_us-gaap_NumberOfOperatingSegments_8e72fdfe-176b-4b78-bb21-71fe670790f7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_NumberOfNonOperatingSegments_94725ea3-f6ea-4e9b-a2c6-aae189b9079a" xlink:href="virt-20240930.xsd#virt_NumberOfNonOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_e8b94c92-22a9-40a4-afdf-16017d6ba5b3" xlink:to="loc_virt_NumberOfNonOperatingSegments_94725ea3-f6ea-4e9b-a2c6-aae189b9079a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_DisposalGroupIncludingDiscontinuedOperationDivestitureOfInterestInJointVenturePercentage_f298a30e-5c1b-47df-b20f-508e467f85a5" xlink:href="virt-20240930.xsd#virt_DisposalGroupIncludingDiscontinuedOperationDivestitureOfInterestInJointVenturePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems_e8b94c92-22a9-40a4-afdf-16017d6ba5b3" xlink:to="loc_virt_DisposalGroupIncludingDiscontinuedOperationDivestitureOfInterestInJointVenturePercentage_f298a30e-5c1b-47df-b20f-508e467f85a5" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/BusinessHeldforSaleNarrativeDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#BusinessHeldforSaleNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/BusinessHeldforSaleNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_32a4ee19-6b96-43b7-9759-c0bdff7b4a27" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_46142d02-9ea2-4d00-89c2-b5e59682ca67" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_32a4ee19-6b96-43b7-9759-c0bdff7b4a27" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_46142d02-9ea2-4d00-89c2-b5e59682ca67" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_de89bc17-79ea-4a6a-88a8-8360ef2a9591" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_46142d02-9ea2-4d00-89c2-b5e59682ca67" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_de89bc17-79ea-4a6a-88a8-8360ef2a9591" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_de89bc17-79ea-4a6a-88a8-8360ef2a9591_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_de89bc17-79ea-4a6a-88a8-8360ef2a9591" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_de89bc17-79ea-4a6a-88a8-8360ef2a9591_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_ea4bca3d-6907-4535-b4b0-e60a18226ca8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_de89bc17-79ea-4a6a-88a8-8360ef2a9591" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_ea4bca3d-6907-4535-b4b0-e60a18226ca8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_70431e0c-42fe-4711-b17a-ea7c21967dc4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_ea4bca3d-6907-4535-b4b0-e60a18226ca8" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_70431e0c-42fe-4711-b17a-ea7c21967dc4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_74941693-0716-4fa0-8fc3-4db3d52cc7dd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_46142d02-9ea2-4d00-89c2-b5e59682ca67" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_74941693-0716-4fa0-8fc3-4db3d52cc7dd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_74941693-0716-4fa0-8fc3-4db3d52cc7dd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_74941693-0716-4fa0-8fc3-4db3d52cc7dd" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_74941693-0716-4fa0-8fc3-4db3d52cc7dd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_0ad1f990-b4af-4f55-975b-da973d335658" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_74941693-0716-4fa0-8fc3-4db3d52cc7dd" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_0ad1f990-b4af-4f55-975b-da973d335658" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RFQHubMember_310fcc63-1f3f-450a-8fa8-f399fda286db" xlink:href="virt-20240930.xsd#virt_RFQHubMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_0ad1f990-b4af-4f55-975b-da973d335658" xlink:to="loc_virt_RFQHubMember_310fcc63-1f3f-450a-8fa8-f399fda286db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_DisposalGroupIncludingDiscontinuedOperationDivestitureOfInterestInJointVenturePercentage_0a6777f1-b85c-4738-bc87-1aa2577bc50b" xlink:href="virt-20240930.xsd#virt_DisposalGroupIncludingDiscontinuedOperationDivestitureOfInterestInJointVenturePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_32a4ee19-6b96-43b7-9759-c0bdff7b4a27" xlink:to="loc_virt_DisposalGroupIncludingDiscontinuedOperationDivestitureOfInterestInJointVenturePercentage_0a6777f1-b85c-4738-bc87-1aa2577bc50b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/BusinessHeldforSaleSummaryofcarryingvalueandgainonsaleofBondPointDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#BusinessHeldforSaleSummaryofcarryingvalueandgainonsaleofBondPointDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/BusinessHeldforSaleSummaryofcarryingvalueandgainonsaleofBondPointDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_4ca85b0e-2715-4822-b970-87746af75972" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_c897dc43-d35f-4a98-b21a-c2db1e47f545" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_4ca85b0e-2715-4822-b970-87746af75972" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_c897dc43-d35f-4a98-b21a-c2db1e47f545" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_6674b99b-94c6-4438-abf7-22f4f0bec75d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_c897dc43-d35f-4a98-b21a-c2db1e47f545" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_6674b99b-94c6-4438-abf7-22f4f0bec75d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6674b99b-94c6-4438-abf7-22f4f0bec75d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_6674b99b-94c6-4438-abf7-22f4f0bec75d" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6674b99b-94c6-4438-abf7-22f4f0bec75d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_a01a7a61-8d92-4491-8236-0c609f4996a6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_6674b99b-94c6-4438-abf7-22f4f0bec75d" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_a01a7a61-8d92-4491-8236-0c609f4996a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RFQHubMember_df779e7a-b839-431c-b5dc-803242bd41d4" xlink:href="virt-20240930.xsd#virt_RFQHubMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_a01a7a61-8d92-4491-8236-0c609f4996a6" xlink:to="loc_virt_RFQHubMember_df779e7a-b839-431c-b5dc-803242bd41d4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_c1ee349f-8aba-4e4b-a0f5-08aaa41fc30c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_c897dc43-d35f-4a98-b21a-c2db1e47f545" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_c1ee349f-8aba-4e4b-a0f5-08aaa41fc30c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_c1ee349f-8aba-4e4b-a0f5-08aaa41fc30c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_c1ee349f-8aba-4e4b-a0f5-08aaa41fc30c" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_c1ee349f-8aba-4e4b-a0f5-08aaa41fc30c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_bd75846a-61c9-45b5-b403-ed5dee99799d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_c1ee349f-8aba-4e4b-a0f5-08aaa41fc30c" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_bd75846a-61c9-45b5-b403-ed5dee99799d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_da3fca59-5c6f-4d1c-847a-ed0402ef3d52" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_bd75846a-61c9-45b5-b403-ed5dee99799d" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_da3fca59-5c6f-4d1c-847a-ed0402ef3d52" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationBalanceSheetDisclosuresAbstract_6148c14d-dcf3-4c6e-85b0-a1720cb5116b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationBalanceSheetDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_4ca85b0e-2715-4822-b970-87746af75972" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationBalanceSheetDisclosuresAbstract_6148c14d-dcf3-4c6e-85b0-a1720cb5116b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_DisposalGroupIncludingDiscontinuedOperationReceivablesFromBrokerDealersAndClearingOrganizations_60d14a00-9244-46e8-8526-16d09cdcf7a9" xlink:href="virt-20240930.xsd#virt_DisposalGroupIncludingDiscontinuedOperationReceivablesFromBrokerDealersAndClearingOrganizations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationBalanceSheetDisclosuresAbstract_6148c14d-dcf3-4c6e-85b0-a1720cb5116b" xlink:to="loc_virt_DisposalGroupIncludingDiscontinuedOperationReceivablesFromBrokerDealersAndClearingOrganizations_60d14a00-9244-46e8-8526-16d09cdcf7a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_DisposalGroupIncludingDiscontinuedOperationPropertyEquipmentAndCapitalizedSoftware_efcfddcc-3734-4cff-a37c-11f7d302a6cc" xlink:href="virt-20240930.xsd#virt_DisposalGroupIncludingDiscontinuedOperationPropertyEquipmentAndCapitalizedSoftware"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationBalanceSheetDisclosuresAbstract_6148c14d-dcf3-4c6e-85b0-a1720cb5116b" xlink:to="loc_virt_DisposalGroupIncludingDiscontinuedOperationPropertyEquipmentAndCapitalizedSoftware_efcfddcc-3734-4cff-a37c-11f7d302a6cc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssets_08200034-0ad2-41b6-82c1-ae4217d5d83d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationBalanceSheetDisclosuresAbstract_6148c14d-dcf3-4c6e-85b0-a1720cb5116b" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssets_08200034-0ad2-41b6-82c1-ae4217d5d83d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherAssets_11f9975c-a862-41d1-ad8b-e03373b0b013" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationBalanceSheetDisclosuresAbstract_6148c14d-dcf3-4c6e-85b0-a1720cb5116b" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherAssets_11f9975c-a862-41d1-ad8b-e03373b0b013" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_2dea0297-947b-4549-b407-8ef8915028b0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationBalanceSheetDisclosuresAbstract_6148c14d-dcf3-4c6e-85b0-a1720cb5116b" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_2dea0297-947b-4549-b407-8ef8915028b0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_DisposalGroupIncludingDiscontinuedOperationAssetsLiabilitiesNet_abccddb9-dd23-42bf-8771-9d391f9b1efd" xlink:href="virt-20240930.xsd#virt_DisposalGroupIncludingDiscontinuedOperationAssetsLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationBalanceSheetDisclosuresAbstract_6148c14d-dcf3-4c6e-85b0-a1720cb5116b" xlink:to="loc_virt_DisposalGroupIncludingDiscontinuedOperationAssetsLiabilitiesNet_abccddb9-dd23-42bf-8771-9d391f9b1efd" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/EarningsperShareBasicDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#EarningsperShareBasicDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/EarningsperShareBasicDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_fb498a07-6007-42f7-ad7d-c6a3808c47a8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_fd052145-ccd5-4551-afd1-3dd7eeba0a20" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_fb498a07-6007-42f7-ad7d-c6a3808c47a8" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_fd052145-ccd5-4551-afd1-3dd7eeba0a20" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_fc1d21e1-cb27-4564-9b42-4bfad2fe0d03" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_fd052145-ccd5-4551-afd1-3dd7eeba0a20" xlink:to="loc_us-gaap_StatementClassOfStockAxis_fc1d21e1-cb27-4564-9b42-4bfad2fe0d03" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_fc1d21e1-cb27-4564-9b42-4bfad2fe0d03_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_fc1d21e1-cb27-4564-9b42-4bfad2fe0d03" xlink:to="loc_us-gaap_ClassOfStockDomain_fc1d21e1-cb27-4564-9b42-4bfad2fe0d03_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_cc693ca7-3384-4caf-a22f-534d873c4f6b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_fc1d21e1-cb27-4564-9b42-4bfad2fe0d03" xlink:to="loc_us-gaap_ClassOfStockDomain_cc693ca7-3384-4caf-a22f-534d873c4f6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_35a2e747-4a28-48de-8c82-38a774db2e13" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_cc693ca7-3384-4caf-a22f-534d873c4f6b" xlink:to="loc_us-gaap_CommonClassAMember_35a2e747-4a28-48de-8c82-38a774db2e13" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicAbstract_92a93c8c-38ef-439b-841a-3a502decc5bd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_fb498a07-6007-42f7-ad7d-c6a3808c47a8" xlink:to="loc_us-gaap_EarningsPerShareBasicAbstract_92a93c8c-38ef-439b-841a-3a502decc5bd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_c2ad6e43-fa33-4fd5-b916-ec1f76a1cf07" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_92a93c8c-38ef-439b-841a-3a502decc5bd" xlink:to="loc_us-gaap_NetIncomeLoss_c2ad6e43-fa33-4fd5-b916-ec1f76a1cf07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossBasic_23a3934c-601a-4efc-9012-140be5a0a677" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_92a93c8c-38ef-439b-841a-3a502decc5bd" xlink:to="loc_us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossBasic_23a3934c-601a-4efc-9012-140be5a0a677" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_3669fc02-0872-4d8f-b42b-31b17aa29ace" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_92a93c8c-38ef-439b-841a-3a502decc5bd" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_3669fc02-0872-4d8f-b42b-31b17aa29ace" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_6f6828eb-9cad-4389-a608-7adb3fc0ecf5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_fb498a07-6007-42f7-ad7d-c6a3808c47a8" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_6f6828eb-9cad-4389-a608-7adb3fc0ecf5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_480c3d1a-a9af-4ad4-8865-dba3d452fba7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_6f6828eb-9cad-4389-a608-7adb3fc0ecf5" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_480c3d1a-a9af-4ad4-8865-dba3d452fba7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_e2c5b63c-dc40-41f5-b997-cabd55ffb5d5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_fb498a07-6007-42f7-ad7d-c6a3808c47a8" xlink:to="loc_us-gaap_EarningsPerShareBasic_e2c5b63c-dc40-41f5-b997-cabd55ffb5d5" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/EarningsperShareDilutedDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#EarningsperShareDilutedDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/EarningsperShareDilutedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_043cd0f3-1efb-418e-a0c1-bc95cfa3d8ec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_5fcf3add-7d27-4369-99a9-aebca35d2d5e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_043cd0f3-1efb-418e-a0c1-bc95cfa3d8ec" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_5fcf3add-7d27-4369-99a9-aebca35d2d5e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_87f7f935-3475-4bc5-b284-9c3fbe5b1004" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_5fcf3add-7d27-4369-99a9-aebca35d2d5e" xlink:to="loc_us-gaap_StatementClassOfStockAxis_87f7f935-3475-4bc5-b284-9c3fbe5b1004" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_87f7f935-3475-4bc5-b284-9c3fbe5b1004_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_87f7f935-3475-4bc5-b284-9c3fbe5b1004" xlink:to="loc_us-gaap_ClassOfStockDomain_87f7f935-3475-4bc5-b284-9c3fbe5b1004_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_252ac57f-f877-44d5-985b-4a531efc46ac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_87f7f935-3475-4bc5-b284-9c3fbe5b1004" xlink:to="loc_us-gaap_ClassOfStockDomain_252ac57f-f877-44d5-985b-4a531efc46ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_4e7a6c15-def1-4da4-9d7a-dc735145df39" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_252ac57f-f877-44d5-985b-4a531efc46ac" xlink:to="loc_us-gaap_CommonClassAMember_4e7a6c15-def1-4da4-9d7a-dc735145df39" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_92076a3f-2be2-4384-9f7e-dd8e4904c2bf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_5fcf3add-7d27-4369-99a9-aebca35d2d5e" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_92076a3f-2be2-4384-9f7e-dd8e4904c2bf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_92076a3f-2be2-4384-9f7e-dd8e4904c2bf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_92076a3f-2be2-4384-9f7e-dd8e4904c2bf" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_92076a3f-2be2-4384-9f7e-dd8e4904c2bf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_0d2762dc-709b-4172-96da-5ececdda8a85" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_92076a3f-2be2-4384-9f7e-dd8e4904c2bf" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_0d2762dc-709b-4172-96da-5ececdda8a85" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_1b74ce0f-2132-43c9-813c-cab8d83a75ff" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_0d2762dc-709b-4172-96da-5ececdda8a85" xlink:to="loc_us-gaap_EmployeeStockOptionMember_1b74ce0f-2132-43c9-813c-cab8d83a75ff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDilutedAbstract_08aab75e-f599-49ee-a7db-ccc966bab20c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareDilutedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_043cd0f3-1efb-418e-a0c1-bc95cfa3d8ec" xlink:to="loc_us-gaap_EarningsPerShareDilutedAbstract_08aab75e-f599-49ee-a7db-ccc966bab20c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_c65b2ac6-be73-4e26-9e32-980ac56937e0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_08aab75e-f599-49ee-a7db-ccc966bab20c" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_c65b2ac6-be73-4e26-9e32-980ac56937e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_1704d6a8-e100-4367-ae2a-78901f643360" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_043cd0f3-1efb-418e-a0c1-bc95cfa3d8ec" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_1704d6a8-e100-4367-ae2a-78901f643360" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_360dc115-04b8-4c5e-96e1-aed7547e07be" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_1704d6a8-e100-4367-ae2a-78901f643360" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_360dc115-04b8-4c5e-96e1-aed7547e07be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_a05ea360-375e-44ac-9636-e1872bcf25c0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_1704d6a8-e100-4367-ae2a-78901f643360" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_a05ea360-375e-44ac-9636-e1872bcf25c0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_d72586e8-77eb-47f0-bbe3-5a7f7028eb4a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_1704d6a8-e100-4367-ae2a-78901f643360" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_d72586e8-77eb-47f0-bbe3-5a7f7028eb4a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_8ff672a3-fe0c-46aa-a637-1c55e92b9599" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_043cd0f3-1efb-418e-a0c1-bc95cfa3d8ec" xlink:to="loc_us-gaap_EarningsPerShareDiluted_8ff672a3-fe0c-46aa-a637-1c55e92b9599" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_c5812e17-5f6f-4d10-b5b1-11a8beac9c1c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_043cd0f3-1efb-418e-a0c1-bc95cfa3d8ec" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_c5812e17-5f6f-4d10-b5b1-11a8beac9c1c" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/TaxReceivableAgreementsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#TaxReceivableAgreementsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/TaxReceivableAgreementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_0b2c51b3-e30c-4412-adf9-7f6f56066a83" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_a05cf274-70b5-4195-b023-c9a7481c79f4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0b2c51b3-e30c-4412-adf9-7f6f56066a83" xlink:to="loc_us-gaap_DebtInstrumentTable_a05cf274-70b5-4195-b023-c9a7481c79f4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_3a74bd41-4810-474a-95f8-68265733f156" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_a05cf274-70b5-4195-b023-c9a7481c79f4" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_3a74bd41-4810-474a-95f8-68265733f156" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_3a74bd41-4810-474a-95f8-68265733f156_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_3a74bd41-4810-474a-95f8-68265733f156" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_3a74bd41-4810-474a-95f8-68265733f156_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_fe76df4e-fc1f-4f78-b7ac-4f6450e6958a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_3a74bd41-4810-474a-95f8-68265733f156" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_fe76df4e-fc1f-4f78-b7ac-4f6450e6958a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_ce4bfcae-4175-438c-b4e7-4f6745852dcb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_fe76df4e-fc1f-4f78-b7ac-4f6450e6958a" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_ce4bfcae-4175-438c-b4e7-4f6745852dcb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_81d71575-b64e-4e86-81e8-e09eada927f7" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_a05cf274-70b5-4195-b023-c9a7481c79f4" xlink:to="loc_dei_LegalEntityAxis_81d71575-b64e-4e86-81e8-e09eada927f7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_81d71575-b64e-4e86-81e8-e09eada927f7_default" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_81d71575-b64e-4e86-81e8-e09eada927f7" xlink:to="loc_dei_EntityDomain_81d71575-b64e-4e86-81e8-e09eada927f7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_d20f8fd6-ec97-48b0-a4e2-702f233d1b0d" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_81d71575-b64e-4e86-81e8-e09eada927f7" xlink:to="loc_dei_EntityDomain_d20f8fd6-ec97-48b0-a4e2-702f233d1b0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VFHParentLLCMember_47e5c493-a6fd-4bc1-8855-11f947c714c1" xlink:href="virt-20240930.xsd#virt_VFHParentLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_d20f8fd6-ec97-48b0-a4e2-702f233d1b0d" xlink:to="loc_virt_VFHParentLLCMember_47e5c493-a6fd-4bc1-8855-11f947c714c1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_TaxReceivableAgreementPayment_ab511979-89cd-48eb-bbc0-2c95b1b73263" xlink:href="virt-20240930.xsd#virt_TaxReceivableAgreementPayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0b2c51b3-e30c-4412-adf9-7f6f56066a83" xlink:to="loc_virt_TaxReceivableAgreementPayment_ab511979-89cd-48eb-bbc0-2c95b1b73263" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_TaxReceivableAgreementObligationsOverPeriodMinimumYearlyPaymentRange_b37e79d7-851b-4025-9359-fc0d8f1789ce" xlink:href="virt-20240930.xsd#virt_TaxReceivableAgreementObligationsOverPeriodMinimumYearlyPaymentRange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0b2c51b3-e30c-4412-adf9-7f6f56066a83" xlink:to="loc_virt_TaxReceivableAgreementObligationsOverPeriodMinimumYearlyPaymentRange_b37e79d7-851b-4025-9359-fc0d8f1789ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_TaxReceivableAgreementObligationsOverPeriodMaximumYearlyPaymentRange_d309811d-c13b-45a6-817a-9738f8a620f5" xlink:href="virt-20240930.xsd#virt_TaxReceivableAgreementObligationsOverPeriodMaximumYearlyPaymentRange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0b2c51b3-e30c-4412-adf9-7f6f56066a83" xlink:to="loc_virt_TaxReceivableAgreementObligationsOverPeriodMaximumYearlyPaymentRange_d309811d-c13b-45a6-817a-9738f8a620f5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_TaxReceivableAgreementObligationsSettlementTerm_96663f27-c256-4c35-a6b2-642fd904fde6" xlink:href="virt-20240930.xsd#virt_TaxReceivableAgreementObligationsSettlementTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0b2c51b3-e30c-4412-adf9-7f6f56066a83" xlink:to="loc_virt_TaxReceivableAgreementObligationsSettlementTerm_96663f27-c256-4c35-a6b2-642fd904fde6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsNet_2c851c81-60dd-41e0-9be7-e9c60fcdeecf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0b2c51b3-e30c-4412-adf9-7f6f56066a83" xlink:to="loc_us-gaap_DeferredTaxAssetsNet_2c851c81-60dd-41e0-9be7-e9c60fcdeecf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_TaxReceivableAgreementObligations_3f0a631e-f9ca-43e1-8b94-f02242e18407" xlink:href="virt-20240930.xsd#virt_TaxReceivableAgreementObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0b2c51b3-e30c-4412-adf9-7f6f56066a83" xlink:to="loc_virt_TaxReceivableAgreementObligations_3f0a631e-f9ca-43e1-8b94-f02242e18407" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/GoodwillandIntangibleAssetsNarrativeDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#GoodwillandIntangibleAssetsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/GoodwillandIntangibleAssetsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_0c8a61bd-83d1-4be2-9fde-f2d3f5ec91c6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_ba72a66d-729c-4ee7-a8e8-0569a65e7ad7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_0c8a61bd-83d1-4be2-9fde-f2d3f5ec91c6" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_ba72a66d-729c-4ee7-a8e8-0569a65e7ad7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_49b671e4-c017-41d8-b003-beb176d305f8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_ba72a66d-729c-4ee7-a8e8-0569a65e7ad7" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_49b671e4-c017-41d8-b003-beb176d305f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_49b671e4-c017-41d8-b003-beb176d305f8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_49b671e4-c017-41d8-b003-beb176d305f8" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_49b671e4-c017-41d8-b003-beb176d305f8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_42335749-e91d-4c3b-9083-d67dfe0efc0d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_49b671e4-c017-41d8-b003-beb176d305f8" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_42335749-e91d-4c3b-9083-d67dfe0efc0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_c0942404-7998-4c71-ae9c-7a664317af75" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_42335749-e91d-4c3b-9083-d67dfe0efc0d" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_c0942404-7998-4c71-ae9c-7a664317af75" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2be938f5-c22a-4609-9b52-f2a79d398e2e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_ba72a66d-729c-4ee7-a8e8-0569a65e7ad7" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2be938f5-c22a-4609-9b52-f2a79d398e2e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_2be938f5-c22a-4609-9b52-f2a79d398e2e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2be938f5-c22a-4609-9b52-f2a79d398e2e" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_2be938f5-c22a-4609-9b52-f2a79d398e2e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1033003f-33c5-4603-aa2d-f4799759030d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2be938f5-c22a-4609-9b52-f2a79d398e2e" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1033003f-33c5-4603-aa2d-f4799759030d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RFQHubMember_98bf8fcf-534c-4196-bfdd-50fe58b02f29" xlink:href="virt-20240930.xsd#virt_RFQHubMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1033003f-33c5-4603-aa2d-f4799759030d" xlink:to="loc_virt_RFQHubMember_98bf8fcf-534c-4196-bfdd-50fe58b02f29" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_9abd19f0-9948-4d69-b518-15fb7055e60b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_0c8a61bd-83d1-4be2-9fde-f2d3f5ec91c6" xlink:to="loc_us-gaap_NumberOfOperatingSegments_9abd19f0-9948-4d69-b518-15fb7055e60b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_NumberOfNonOperatingSegments_be5c354d-cb78-4af0-8669-7065622e3bf6" xlink:href="virt-20240930.xsd#virt_NumberOfNonOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_0c8a61bd-83d1-4be2-9fde-f2d3f5ec91c6" xlink:to="loc_virt_NumberOfNonOperatingSegments_be5c354d-cb78-4af0-8669-7065622e3bf6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_33f633b0-0ca5-455a-a9b1-ccc4cd7fbbe9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_0c8a61bd-83d1-4be2-9fde-f2d3f5ec91c6" xlink:to="loc_us-gaap_Goodwill_33f633b0-0ca5-455a-a9b1-ccc4cd7fbbe9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_a20df576-957e-4e0e-afa5-61a8fdcde902" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_0c8a61bd-83d1-4be2-9fde-f2d3f5ec91c6" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_a20df576-957e-4e0e-afa5-61a8fdcde902" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_5cfa8496-b2ef-4524-b14a-f96054641e77" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_0c8a61bd-83d1-4be2-9fde-f2d3f5ec91c6" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_5cfa8496-b2ef-4524-b14a-f96054641e77" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_28f5705d-8552-4f3d-a577-0460c9ddf5cd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_0c8a61bd-83d1-4be2-9fde-f2d3f5ec91c6" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_28f5705d-8552-4f3d-a577-0460c9ddf5cd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_876c9751-2410-41dd-ab93-69370f651408" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_0c8a61bd-83d1-4be2-9fde-f2d3f5ec91c6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_876c9751-2410-41dd-ab93-69370f651408" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_2444457b-c436-464c-b302-1d609b701ac8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_0c8a61bd-83d1-4be2-9fde-f2d3f5ec91c6" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_2444457b-c436-464c-b302-1d609b701ac8" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/GoodwillandIntangibleAssetsGoodwillDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#GoodwillandIntangibleAssetsGoodwillDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/GoodwillandIntangibleAssetsGoodwillDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_a9195344-0587-49a9-a73e-92b918099401" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_03ade5fe-65b7-4eee-82a8-a380433fd1b0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_a9195344-0587-49a9-a73e-92b918099401" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_03ade5fe-65b7-4eee-82a8-a380433fd1b0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_a32a4adf-8f03-4ac2-929d-6d70f1fc9ee0" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_03ade5fe-65b7-4eee-82a8-a380433fd1b0" xlink:to="loc_srt_ConsolidationItemsAxis_a32a4adf-8f03-4ac2-929d-6d70f1fc9ee0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_a32a4adf-8f03-4ac2-929d-6d70f1fc9ee0_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_a32a4adf-8f03-4ac2-929d-6d70f1fc9ee0" xlink:to="loc_srt_ConsolidationItemsDomain_a32a4adf-8f03-4ac2-929d-6d70f1fc9ee0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_6b407f48-5a7d-4fc7-b28f-f313d2838a7e" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_a32a4adf-8f03-4ac2-929d-6d70f1fc9ee0" xlink:to="loc_srt_ConsolidationItemsDomain_6b407f48-5a7d-4fc7-b28f-f313d2838a7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_b7a84a4e-2b11-48bc-aed6-8ef5de340c55" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_6b407f48-5a7d-4fc7-b28f-f313d2838a7e" xlink:to="loc_us-gaap_OperatingSegmentsMember_b7a84a4e-2b11-48bc-aed6-8ef5de340c55" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_c34ebe1a-1cd4-4d03-b293-7e69ab9f3d97" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_6b407f48-5a7d-4fc7-b28f-f313d2838a7e" xlink:to="loc_us-gaap_CorporateNonSegmentMember_c34ebe1a-1cd4-4d03-b293-7e69ab9f3d97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_d083976e-59c3-4b7e-9ad0-fbe559ff702b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_03ade5fe-65b7-4eee-82a8-a380433fd1b0" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_d083976e-59c3-4b7e-9ad0-fbe559ff702b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_d083976e-59c3-4b7e-9ad0-fbe559ff702b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_d083976e-59c3-4b7e-9ad0-fbe559ff702b" xlink:to="loc_us-gaap_SegmentDomain_d083976e-59c3-4b7e-9ad0-fbe559ff702b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_5c26308e-79d7-40ca-9dc0-e2352ef5caaa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_d083976e-59c3-4b7e-9ad0-fbe559ff702b" xlink:to="loc_us-gaap_SegmentDomain_5c26308e-79d7-40ca-9dc0-e2352ef5caaa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_MarketMakingSegmentMember_cb5c557b-b5f8-46e0-a15a-747d0a203a1c" xlink:href="virt-20240930.xsd#virt_MarketMakingSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_5c26308e-79d7-40ca-9dc0-e2352ef5caaa" xlink:to="loc_virt_MarketMakingSegmentMember_cb5c557b-b5f8-46e0-a15a-747d0a203a1c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ExecutionServicesSegmentMember_148ff962-764a-4046-bd2e-bf13be4651f8" xlink:href="virt-20240930.xsd#virt_ExecutionServicesSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_5c26308e-79d7-40ca-9dc0-e2352ef5caaa" xlink:to="loc_virt_ExecutionServicesSegmentMember_148ff962-764a-4046-bd2e-bf13be4651f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_b1ae3b27-c4a8-4fa0-8c18-4aa63b81efa2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_a9195344-0587-49a9-a73e-92b918099401" xlink:to="loc_us-gaap_Goodwill_b1ae3b27-c4a8-4fa0-8c18-4aa63b81efa2" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/GoodwillandIntangibleAssetsIntangibleAssetsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#GoodwillandIntangibleAssetsIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/GoodwillandIntangibleAssetsIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_e128e5ae-3fed-4bcb-93ce-7f4e55c6c625" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_c34c0502-3a0d-498f-94d4-51744049b351" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_e128e5ae-3fed-4bcb-93ce-7f4e55c6c625" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_c34c0502-3a0d-498f-94d4-51744049b351" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_d25827b7-88c1-4ecf-ab16-514748b4964e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_c34c0502-3a0d-498f-94d4-51744049b351" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_d25827b7-88c1-4ecf-ab16-514748b4964e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d25827b7-88c1-4ecf-ab16-514748b4964e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_d25827b7-88c1-4ecf-ab16-514748b4964e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d25827b7-88c1-4ecf-ab16-514748b4964e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f47a1d3c-d2d9-4943-8bab-f08020f80058" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_d25827b7-88c1-4ecf-ab16-514748b4964e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f47a1d3c-d2d9-4943-8bab-f08020f80058" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_94eaed84-05d1-4d22-9f6b-6166e43933de" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f47a1d3c-d2d9-4943-8bab-f08020f80058" xlink:to="loc_us-gaap_CustomerRelationshipsMember_94eaed84-05d1-4d22-9f6b-6166e43933de" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_d8110b8c-087b-49ec-918d-084bf5526bf1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DevelopedTechnologyRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f47a1d3c-d2d9-4943-8bab-f08020f80058" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_d8110b8c-087b-49ec-918d-084bf5526bf1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffMarketFavorableLeaseMember_41b56f2f-04e7-489e-98f5-c9e22d0f81ce" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OffMarketFavorableLeaseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f47a1d3c-d2d9-4943-8bab-f08020f80058" xlink:to="loc_us-gaap_OffMarketFavorableLeaseMember_41b56f2f-04e7-489e-98f5-c9e22d0f81ce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_ca297c94-232c-4141-b647-1dc944098db5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f47a1d3c-d2d9-4943-8bab-f08020f80058" xlink:to="loc_us-gaap_TradeNamesMember_ca297c94-232c-4141-b647-1dc944098db5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ExchangeTradedFundsIssuerRelationshipsMember_408fe2f3-6f39-4547-98db-9e9aebd30e9e" xlink:href="virt-20240930.xsd#virt_ExchangeTradedFundsIssuerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f47a1d3c-d2d9-4943-8bab-f08020f80058" xlink:to="loc_virt_ExchangeTradedFundsIssuerRelationshipsMember_408fe2f3-6f39-4547-98db-9e9aebd30e9e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ExchangeTradedFundsBuyerRelationshipsMember_93a0ee1c-5af3-4b2b-a9e3-99d03924d12a" xlink:href="virt-20240930.xsd#virt_ExchangeTradedFundsBuyerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f47a1d3c-d2d9-4943-8bab-f08020f80058" xlink:to="loc_virt_ExchangeTradedFundsBuyerRelationshipsMember_93a0ee1c-5af3-4b2b-a9e3-99d03924d12a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_3ce9a653-e2af-4786-99d3-150eeb9c26b4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_c34c0502-3a0d-498f-94d4-51744049b351" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_3ce9a653-e2af-4786-99d3-150eeb9c26b4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_3ce9a653-e2af-4786-99d3-150eeb9c26b4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_3ce9a653-e2af-4786-99d3-150eeb9c26b4" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_3ce9a653-e2af-4786-99d3-150eeb9c26b4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_ab017f51-23f2-4f12-bf32-cd1263a5d89b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_3ce9a653-e2af-4786-99d3-150eeb9c26b4" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_ab017f51-23f2-4f12-bf32-cd1263a5d89b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ExchangeMembershipsMember_963e4120-b8be-4c4f-9c43-9304d8bf729d" xlink:href="virt-20240930.xsd#virt_ExchangeMembershipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_ab017f51-23f2-4f12-bf32-cd1263a5d89b" xlink:to="loc_virt_ExchangeMembershipsMember_963e4120-b8be-4c4f-9c43-9304d8bf729d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_OtherTradeMember_b5af6b97-057d-46b6-946a-7a6a3edaa624" xlink:href="virt-20240930.xsd#virt_OtherTradeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_ab017f51-23f2-4f12-bf32-cd1263a5d89b" xlink:to="loc_virt_OtherTradeMember_b5af6b97-057d-46b6-946a-7a6a3edaa624" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_a38a14e1-5b47-4797-aa2f-5b932804e721" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_c34c0502-3a0d-498f-94d4-51744049b351" xlink:to="loc_srt_RangeAxis_a38a14e1-5b47-4797-aa2f-5b932804e721" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a38a14e1-5b47-4797-aa2f-5b932804e721_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_a38a14e1-5b47-4797-aa2f-5b932804e721" xlink:to="loc_srt_RangeMember_a38a14e1-5b47-4797-aa2f-5b932804e721_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_27c34be9-40fa-4c5e-bf3e-9879af345c87" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_a38a14e1-5b47-4797-aa2f-5b932804e721" xlink:to="loc_srt_RangeMember_27c34be9-40fa-4c5e-bf3e-9879af345c87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_cf59b81c-7fcb-41d0-81f8-749100a21913" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_27c34be9-40fa-4c5e-bf3e-9879af345c87" xlink:to="loc_srt_MinimumMember_cf59b81c-7fcb-41d0-81f8-749100a21913" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_717dc873-ca79-44c9-b7c1-42e56cf99c88" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_27c34be9-40fa-4c5e-bf3e-9879af345c87" xlink:to="loc_srt_MaximumMember_717dc873-ca79-44c9-b7c1-42e56cf99c88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_e854da86-b498-4f92-9013-2857b8dccf70" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_e128e5ae-3fed-4bcb-93ce-7f4e55c6c625" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_e854da86-b498-4f92-9013-2857b8dccf70" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_d1868c0b-3346-4f78-9eca-ea634b0da878" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_e128e5ae-3fed-4bcb-93ce-7f4e55c6c625" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_d1868c0b-3346-4f78-9eca-ea634b0da878" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_a53a6cb6-4ea4-4127-bb0f-6994358ca797" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_e128e5ae-3fed-4bcb-93ce-7f4e55c6c625" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_a53a6cb6-4ea4-4127-bb0f-6994358ca797" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_bb6b7dfa-a04b-4d7b-9bf5-4df7573f772d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_e128e5ae-3fed-4bcb-93ce-7f4e55c6c625" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_bb6b7dfa-a04b-4d7b-9bf5-4df7573f772d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_5ae3e0c7-8e5e-4e1e-9f86-064c7787a587" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_e128e5ae-3fed-4bcb-93ce-7f4e55c6c625" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_5ae3e0c7-8e5e-4e1e-9f86-064c7787a587" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_64a6cd72-5fe2-4149-8df3-d392d31fc5d6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_e128e5ae-3fed-4bcb-93ce-7f4e55c6c625" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_64a6cd72-5fe2-4149-8df3-d392d31fc5d6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_1cb4f057-4229-43c2-bbf1-7b28bd5da123" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_e128e5ae-3fed-4bcb-93ce-7f4e55c6c625" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_1cb4f057-4229-43c2-bbf1-7b28bd5da123" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/CollateralizedTransactionsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#CollateralizedTransactionsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/CollateralizedTransactionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralLineItems_589c4e71-7e20-4b50-881c-7db48363686c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralTable_1aeb1314-5400-41b0-aba6-07d434d0c555" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralLineItems_589c4e71-7e20-4b50-881c-7db48363686c" xlink:to="loc_us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralTable_1aeb1314-5400-41b0-aba6-07d434d0c555" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_1297ff66-aa52-463d-bb36-f28381302090" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralTable_1aeb1314-5400-41b0-aba6-07d434d0c555" xlink:to="loc_us-gaap_FinancialInstrumentAxis_1297ff66-aa52-463d-bb36-f28381302090" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_1297ff66-aa52-463d-bb36-f28381302090_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_1297ff66-aa52-463d-bb36-f28381302090" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_1297ff66-aa52-463d-bb36-f28381302090_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_6605d763-40c8-4698-a59c-7f16c404b956" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_1297ff66-aa52-463d-bb36-f28381302090" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_6605d763-40c8-4698-a59c-7f16c404b956" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesMember_690192c9-cbb3-4213-a40c-6a5a4f4a84b4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_6605d763-40c8-4698-a59c-7f16c404b956" xlink:to="loc_us-gaap_EquitySecuritiesMember_690192c9-cbb3-4213-a40c-6a5a4f4a84b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ExchangeTradedNotesMember_f199494e-60ba-4249-95d2-f120b7268832" xlink:href="virt-20240930.xsd#virt_ExchangeTradedNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_6605d763-40c8-4698-a59c-7f16c404b956" xlink:to="loc_virt_ExchangeTradedNotesMember_f199494e-60ba-4249-95d2-f120b7268832" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusAxis_78edf777-7ad1-41a4-ba9b-2e6bebca8583" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PledgedStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralTable_1aeb1314-5400-41b0-aba6-07d434d0c555" xlink:to="loc_us-gaap_PledgedStatusAxis_78edf777-7ad1-41a4-ba9b-2e6bebca8583" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusDomain_78edf777-7ad1-41a4-ba9b-2e6bebca8583_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PledgedStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PledgedStatusAxis_78edf777-7ad1-41a4-ba9b-2e6bebca8583" xlink:to="loc_us-gaap_PledgedStatusDomain_78edf777-7ad1-41a4-ba9b-2e6bebca8583_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusDomain_c5e37c92-8ffd-4005-905d-7b0c80a21783" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PledgedStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PledgedStatusAxis_78edf777-7ad1-41a4-ba9b-2e6bebca8583" xlink:to="loc_us-gaap_PledgedStatusDomain_c5e37c92-8ffd-4005-905d-7b0c80a21783" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetPledgedAsCollateralMember_7edc89c2-98f7-4840-93c2-777d43232c76" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetPledgedAsCollateralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PledgedStatusDomain_c5e37c92-8ffd-4005-905d-7b0c80a21783" xlink:to="loc_us-gaap_AssetPledgedAsCollateralMember_7edc89c2-98f7-4840-93c2-777d43232c76" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesReceivedAsCollateralAbstract_efb6723f-a3d5-437a-a6e8-ab2294ca74dd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesReceivedAsCollateralAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralLineItems_589c4e71-7e20-4b50-881c-7db48363686c" xlink:to="loc_us-gaap_SecuritiesReceivedAsCollateralAbstract_efb6723f-a3d5-437a-a6e8-ab2294ca74dd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SecuritiesBorrowedAtMarketValue_6e8d3e52-bf3e-4825-b10e-1a33aeb87404" xlink:href="virt-20240930.xsd#virt_SecuritiesBorrowedAtMarketValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SecuritiesReceivedAsCollateralAbstract_efb6723f-a3d5-437a-a6e8-ab2294ca74dd" xlink:to="loc_virt_SecuritiesBorrowedAtMarketValue_6e8d3e52-bf3e-4825-b10e-1a33aeb87404" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalFundsSoldAndSecuritiesPurchasedUnderAgreementsToResellPledgedAsCollateral_21d3b4be-12c5-4b64-a5d1-4bac3c3b35cc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FederalFundsSoldAndSecuritiesPurchasedUnderAgreementsToResellPledgedAsCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SecuritiesReceivedAsCollateralAbstract_efb6723f-a3d5-437a-a6e8-ab2294ca74dd" xlink:to="loc_us-gaap_FederalFundsSoldAndSecuritiesPurchasedUnderAgreementsToResellPledgedAsCollateral_21d3b4be-12c5-4b64-a5d1-4bac3c3b35cc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralizedAgreements_cda0a2db-5125-4f6e-84ef-0036be5c24f1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CollateralizedAgreements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SecuritiesReceivedAsCollateralAbstract_efb6723f-a3d5-437a-a6e8-ab2294ca74dd" xlink:to="loc_us-gaap_CollateralizedAgreements_cda0a2db-5125-4f6e-84ef-0036be5c24f1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentsOwnedAtFairValue_ca20393d-4a6f-44d6-8492-b003b063a981" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentsOwnedAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SecuritiesReceivedAsCollateralAbstract_efb6723f-a3d5-437a-a6e8-ab2294ca74dd" xlink:to="loc_us-gaap_FinancialInstrumentsOwnedAtFairValue_ca20393d-4a6f-44d6-8492-b003b063a981" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/BorrowingsShorttermBorrowingsnetDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#BorrowingsShorttermBorrowingsnetDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/BorrowingsShorttermBorrowingsnetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtLineItems_14466dce-d144-4dad-9de7-b5969b8e00d4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShortTermDebtLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShortTermDebtTable_0bf1395f-cafa-40be-a37d-a02644f6bf9d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShortTermDebtTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShortTermDebtLineItems_14466dce-d144-4dad-9de7-b5969b8e00d4" xlink:to="loc_us-gaap_ScheduleOfShortTermDebtTable_0bf1395f-cafa-40be-a37d-a02644f6bf9d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_035626ef-a530-4d1a-8205-91897dc3e54a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShortTermDebtTable_0bf1395f-cafa-40be-a37d-a02644f6bf9d" xlink:to="loc_us-gaap_CreditFacilityAxis_035626ef-a530-4d1a-8205-91897dc3e54a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_035626ef-a530-4d1a-8205-91897dc3e54a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_035626ef-a530-4d1a-8205-91897dc3e54a" xlink:to="loc_us-gaap_CreditFacilityDomain_035626ef-a530-4d1a-8205-91897dc3e54a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_ed29199a-e333-4665-bf90-dcc8812b4f7a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_035626ef-a530-4d1a-8205-91897dc3e54a" xlink:to="loc_us-gaap_CreditFacilityDomain_ed29199a-e333-4665-bf90-dcc8812b4f7a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_BrokerDealerCreditFacilitiesMember_92409a2a-d7e6-484a-9e6b-58bce1c13507" xlink:href="virt-20240930.xsd#virt_BrokerDealerCreditFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_ed29199a-e333-4665-bf90-dcc8812b4f7a" xlink:to="loc_virt_BrokerDealerCreditFacilitiesMember_92409a2a-d7e6-484a-9e6b-58bce1c13507" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_73d80eb9-8029-4a11-993d-b627cce0a6cc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShortTermDebtTable_0bf1395f-cafa-40be-a37d-a02644f6bf9d" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_73d80eb9-8029-4a11-993d-b627cce0a6cc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_73d80eb9-8029-4a11-993d-b627cce0a6cc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_73d80eb9-8029-4a11-993d-b627cce0a6cc" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_73d80eb9-8029-4a11-993d-b627cce0a6cc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_d22e29bf-de90-4508-b14f-452321261dd9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_73d80eb9-8029-4a11-993d-b627cce0a6cc" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_d22e29bf-de90-4508-b14f-452321261dd9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableToBanksMember_3da2d60a-a252-42f8-8934-74db0e3e4715" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NotesPayableToBanksMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_d22e29bf-de90-4508-b14f-452321261dd9" xlink:to="loc_us-gaap_NotesPayableToBanksMember_3da2d60a-a252-42f8-8934-74db0e3e4715" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansPayableMember_37b75067-7b40-49a6-83b6-21bec49f818b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LoansPayableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_d22e29bf-de90-4508-b14f-452321261dd9" xlink:to="loc_us-gaap_LoansPayableMember_37b75067-7b40-49a6-83b6-21bec49f818b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ShortTermDebtGross_69aeef8b-6ab5-4826-81e1-9cba0057ce92" xlink:href="virt-20240930.xsd#virt_ShortTermDebtGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_14466dce-d144-4dad-9de7-b5969b8e00d4" xlink:to="loc_virt_ShortTermDebtGross_69aeef8b-6ab5-4826-81e1-9cba0057ce92" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_caade9b8-0c52-4167-bccb-e0a8cf8e49c0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_14466dce-d144-4dad-9de7-b5969b8e00d4" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_caade9b8-0c52-4167-bccb-e0a8cf8e49c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermBorrowings_a47e0389-d7ab-41c5-ac53-011610dfc2e0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShortTermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_14466dce-d144-4dad-9de7-b5969b8e00d4" xlink:to="loc_us-gaap_ShortTermBorrowings_a47e0389-d7ab-41c5-ac53-011610dfc2e0" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/BorrowingsBrokerDealerCreditFacilitiesDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#BorrowingsBrokerDealerCreditFacilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/BorrowingsBrokerDealerCreditFacilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_63475bc7-3b2e-4fec-a381-cf04b6f6da82" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_aa0a3936-1a0e-4a61-956f-41a4600b4603" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_63475bc7-3b2e-4fec-a381-cf04b6f6da82" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_aa0a3936-1a0e-4a61-956f-41a4600b4603" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_d7c12d7b-2423-40a7-88ac-7f51ddd85e9e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_aa0a3936-1a0e-4a61-956f-41a4600b4603" xlink:to="loc_us-gaap_CreditFacilityAxis_d7c12d7b-2423-40a7-88ac-7f51ddd85e9e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_d7c12d7b-2423-40a7-88ac-7f51ddd85e9e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_d7c12d7b-2423-40a7-88ac-7f51ddd85e9e" xlink:to="loc_us-gaap_CreditFacilityDomain_d7c12d7b-2423-40a7-88ac-7f51ddd85e9e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_6d31ccd8-6d70-452a-b355-c4033cb2f244" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_d7c12d7b-2423-40a7-88ac-7f51ddd85e9e" xlink:to="loc_us-gaap_CreditFacilityDomain_6d31ccd8-6d70-452a-b355-c4033cb2f244" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_BrokerDealerCreditFacilitiesMember_8ccaa8a5-38fb-43cf-879f-e224f089e747" xlink:href="virt-20240930.xsd#virt_BrokerDealerCreditFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_6d31ccd8-6d70-452a-b355-c4033cb2f244" xlink:to="loc_virt_BrokerDealerCreditFacilitiesMember_8ccaa8a5-38fb-43cf-879f-e224f089e747" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_UncommittedBrokerDealerCreditFacilityMember_c47e78bc-cee6-4633-ba6d-0d610e1e88e0" xlink:href="virt-20240930.xsd#virt_UncommittedBrokerDealerCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_6d31ccd8-6d70-452a-b355-c4033cb2f244" xlink:to="loc_virt_UncommittedBrokerDealerCreditFacilityMember_c47e78bc-cee6-4633-ba6d-0d610e1e88e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_4e55c1a9-821d-4307-b1e3-1968992a5048" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_aa0a3936-1a0e-4a61-956f-41a4600b4603" xlink:to="loc_us-gaap_DebtInstrumentAxis_4e55c1a9-821d-4307-b1e3-1968992a5048" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_4e55c1a9-821d-4307-b1e3-1968992a5048_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_4e55c1a9-821d-4307-b1e3-1968992a5048" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_4e55c1a9-821d-4307-b1e3-1968992a5048_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_fbf99657-1062-467e-8aea-6bdcc0f2440f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_4e55c1a9-821d-4307-b1e3-1968992a5048" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_fbf99657-1062-467e-8aea-6bdcc0f2440f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_BorrowingBaseALoanMember_133595ca-82dd-46ac-8fb4-5d8292613240" xlink:href="virt-20240930.xsd#virt_BorrowingBaseALoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_fbf99657-1062-467e-8aea-6bdcc0f2440f" xlink:to="loc_virt_BorrowingBaseALoanMember_133595ca-82dd-46ac-8fb4-5d8292613240" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_BorrowingBaseBLoanMember_7e2599be-4e25-43cc-86d4-4e9a24d05da0" xlink:href="virt-20240930.xsd#virt_BorrowingBaseBLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_fbf99657-1062-467e-8aea-6bdcc0f2440f" xlink:to="loc_virt_BorrowingBaseBLoanMember_7e2599be-4e25-43cc-86d4-4e9a24d05da0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuFinancialSingaporePteLtdMember_bb4f9bf7-5612-4839-95cf-d92ac5041c04" xlink:href="virt-20240930.xsd#virt_VirtuFinancialSingaporePteLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_fbf99657-1062-467e-8aea-6bdcc0f2440f" xlink:to="loc_virt_VirtuFinancialSingaporePteLtdMember_bb4f9bf7-5612-4839-95cf-d92ac5041c04" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_NumberOfSecuredCreditFacilities_9ae083db-a1c3-4609-9fa5-3475a8ee0f27" xlink:href="virt-20240930.xsd#virt_NumberOfSecuredCreditFacilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_63475bc7-3b2e-4fec-a381-cf04b6f6da82" xlink:to="loc_virt_NumberOfSecuredCreditFacilities_9ae083db-a1c3-4609-9fa5-3475a8ee0f27" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_7dfcc951-5aee-471f-aa4d-023b28c097b9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_63475bc7-3b2e-4fec-a381-cf04b6f6da82" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_7dfcc951-5aee-471f-aa4d-023b28c097b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_NumberOfBorrowingBases_76750029-4c5c-42b5-96d9-05287f9dd940" xlink:href="virt-20240930.xsd#virt_NumberOfBorrowingBases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_63475bc7-3b2e-4fec-a381-cf04b6f6da82" xlink:to="loc_virt_NumberOfBorrowingBases_76750029-4c5c-42b5-96d9-05287f9dd940" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_b437aff5-a35d-4e79-8894-317a043a1ac3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_63475bc7-3b2e-4fec-a381-cf04b6f6da82" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_b437aff5-a35d-4e79-8894-317a043a1ac3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_0577c5c8-2394-473b-a1e5-d33667f5c8c2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_63475bc7-3b2e-4fec-a381-cf04b6f6da82" xlink:to="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_0577c5c8-2394-473b-a1e5-d33667f5c8c2" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/BorrowingsBrokerDealerCreditFacilitiesCarryingValuesNetDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#BorrowingsBrokerDealerCreditFacilitiesCarryingValuesNetDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/BorrowingsBrokerDealerCreditFacilitiesCarryingValuesNetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_82ce83f2-0862-4568-a4d2-ca70c6654c40" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_77d35d67-fc16-4f7d-aaae-e9821bb72d90" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_82ce83f2-0862-4568-a4d2-ca70c6654c40" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_77d35d67-fc16-4f7d-aaae-e9821bb72d90" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_3c22a2ed-aa7e-4d8f-992a-b74ab9de7b20" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_77d35d67-fc16-4f7d-aaae-e9821bb72d90" xlink:to="loc_us-gaap_CreditFacilityAxis_3c22a2ed-aa7e-4d8f-992a-b74ab9de7b20" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_3c22a2ed-aa7e-4d8f-992a-b74ab9de7b20_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_3c22a2ed-aa7e-4d8f-992a-b74ab9de7b20" xlink:to="loc_us-gaap_CreditFacilityDomain_3c22a2ed-aa7e-4d8f-992a-b74ab9de7b20_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_9e322f04-130c-45ed-b4ad-7af5681f4120" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_3c22a2ed-aa7e-4d8f-992a-b74ab9de7b20" xlink:to="loc_us-gaap_CreditFacilityDomain_9e322f04-130c-45ed-b4ad-7af5681f4120" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_BrokerDealerCreditFacilitiesMember_1b3e9789-f12b-472f-affc-fc2ca9ee6308" xlink:href="virt-20240930.xsd#virt_BrokerDealerCreditFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_9e322f04-130c-45ed-b4ad-7af5681f4120" xlink:to="loc_virt_BrokerDealerCreditFacilitiesMember_1b3e9789-f12b-472f-affc-fc2ca9ee6308" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_UncommittedBrokerDealerCreditFacilityMember_8fe97ad9-6426-489c-8528-44f487db64b0" xlink:href="virt-20240930.xsd#virt_UncommittedBrokerDealerCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_BrokerDealerCreditFacilitiesMember_1b3e9789-f12b-472f-affc-fc2ca9ee6308" xlink:to="loc_virt_UncommittedBrokerDealerCreditFacilityMember_8fe97ad9-6426-489c-8528-44f487db64b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_22ed2051-b92a-4a91-baf6-f1495d404649" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_BrokerDealerCreditFacilitiesMember_1b3e9789-f12b-472f-affc-fc2ca9ee6308" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_22ed2051-b92a-4a91-baf6-f1495d404649" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_OverdraftFacilityMember_daa4480c-4d33-443f-bbec-b0a8865f6435" xlink:href="virt-20240930.xsd#virt_OverdraftFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_BrokerDealerCreditFacilitiesMember_1b3e9789-f12b-472f-affc-fc2ca9ee6308" xlink:to="loc_virt_OverdraftFacilityMember_daa4480c-4d33-443f-bbec-b0a8865f6435" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_c6017bbc-8fac-4a5a-95c3-21a3089d4a3e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_77d35d67-fc16-4f7d-aaae-e9821bb72d90" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_c6017bbc-8fac-4a5a-95c3-21a3089d4a3e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_c6017bbc-8fac-4a5a-95c3-21a3089d4a3e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_c6017bbc-8fac-4a5a-95c3-21a3089d4a3e" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_c6017bbc-8fac-4a5a-95c3-21a3089d4a3e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_52f8b1ae-4a35-41cb-ba48-51bfea982f02" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_c6017bbc-8fac-4a5a-95c3-21a3089d4a3e" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_52f8b1ae-4a35-41cb-ba48-51bfea982f02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsMember_31ad1edf-3502-4e2c-ac90-9bc21ddf011b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_52f8b1ae-4a35-41cb-ba48-51bfea982f02" xlink:to="loc_us-gaap_OtherAssetsMember_31ad1edf-3502-4e2c-ac90-9bc21ddf011b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_b1cd6497-9db2-416f-b8c7-d992083d394d" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_77d35d67-fc16-4f7d-aaae-e9821bb72d90" xlink:to="loc_srt_RangeAxis_b1cd6497-9db2-416f-b8c7-d992083d394d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_b1cd6497-9db2-416f-b8c7-d992083d394d_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_b1cd6497-9db2-416f-b8c7-d992083d394d" xlink:to="loc_srt_RangeMember_b1cd6497-9db2-416f-b8c7-d992083d394d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_422df25a-2391-4a8e-b54c-172a42ceb0f2" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_b1cd6497-9db2-416f-b8c7-d992083d394d" xlink:to="loc_srt_RangeMember_422df25a-2391-4a8e-b54c-172a42ceb0f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_01afc62b-346b-4806-984c-aa48be376471" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_422df25a-2391-4a8e-b54c-172a42ceb0f2" xlink:to="loc_srt_MaximumMember_01afc62b-346b-4806-984c-aa48be376471" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_2f41cc0c-851f-4e24-ae69-33d433f47454" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_82ce83f2-0862-4568-a4d2-ca70c6654c40" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_2f41cc0c-851f-4e24-ae69-33d433f47454" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_7d7e8970-d15b-4d75-964b-a2949938ed47" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_82ce83f2-0862-4568-a4d2-ca70c6654c40" xlink:to="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_7d7e8970-d15b-4d75-964b-a2949938ed47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_ea712743-0bda-4013-863a-590f7afdc054" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_82ce83f2-0862-4568-a4d2-ca70c6654c40" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_ea712743-0bda-4013-863a-590f7afdc054" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_61bb271b-e699-46e7-80ff-5db5f071e690" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_82ce83f2-0862-4568-a4d2-ca70c6654c40" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_61bb271b-e699-46e7-80ff-5db5f071e690" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_5f766413-7a40-409e-b767-948ccf11e021" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_82ce83f2-0862-4568-a4d2-ca70c6654c40" xlink:to="loc_us-gaap_LongTermDebt_5f766413-7a40-409e-b767-948ccf11e021" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/BorrowingsInterestExpenseonBrokerDealerFacilitiesDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#BorrowingsInterestExpenseonBrokerDealerFacilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/BorrowingsInterestExpenseonBrokerDealerFacilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_b452c613-3395-432e-9ee5-b42afd831db3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_2414d9a2-95f6-4749-9a49-e9e934bbf20a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_b452c613-3395-432e-9ee5-b42afd831db3" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_2414d9a2-95f6-4749-9a49-e9e934bbf20a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_d83d9b82-a87c-4ac5-a861-0ff773267800" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_2414d9a2-95f6-4749-9a49-e9e934bbf20a" xlink:to="loc_us-gaap_CreditFacilityAxis_d83d9b82-a87c-4ac5-a861-0ff773267800" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_d83d9b82-a87c-4ac5-a861-0ff773267800_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_d83d9b82-a87c-4ac5-a861-0ff773267800" xlink:to="loc_us-gaap_CreditFacilityDomain_d83d9b82-a87c-4ac5-a861-0ff773267800_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_9213aa1b-6a7c-4313-9894-d8948a80bf4e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_d83d9b82-a87c-4ac5-a861-0ff773267800" xlink:to="loc_us-gaap_CreditFacilityDomain_9213aa1b-6a7c-4313-9894-d8948a80bf4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_BrokerDealerCreditFacilitiesMember_a0410726-2551-45d3-9942-3da981e5a9b4" xlink:href="virt-20240930.xsd#virt_BrokerDealerCreditFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_9213aa1b-6a7c-4313-9894-d8948a80bf4e" xlink:to="loc_virt_BrokerDealerCreditFacilitiesMember_a0410726-2551-45d3-9942-3da981e5a9b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_UncommittedBrokerDealerCreditFacilityMember_7e1c7e5a-a5f8-4fa2-9a83-439781a5a10e" xlink:href="virt-20240930.xsd#virt_UncommittedBrokerDealerCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_BrokerDealerCreditFacilitiesMember_a0410726-2551-45d3-9942-3da981e5a9b4" xlink:to="loc_virt_UncommittedBrokerDealerCreditFacilityMember_7e1c7e5a-a5f8-4fa2-9a83-439781a5a10e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_9df7de0b-d50f-4d79-b593-b59e01375268" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_BrokerDealerCreditFacilitiesMember_a0410726-2551-45d3-9942-3da981e5a9b4" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_9df7de0b-d50f-4d79-b593-b59e01375268" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_OverdraftFacilityMember_6a7b3b7d-af89-4dfa-87a6-2d9f5fd15777" xlink:href="virt-20240930.xsd#virt_OverdraftFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_BrokerDealerCreditFacilitiesMember_a0410726-2551-45d3-9942-3da981e5a9b4" xlink:to="loc_virt_OverdraftFacilityMember_6a7b3b7d-af89-4dfa-87a6-2d9f5fd15777" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebt_aa3b4d9c-6d84-4bfd-a409-fa91532bc0b1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestExpenseDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_b452c613-3395-432e-9ee5-b42afd831db3" xlink:to="loc_us-gaap_InterestExpenseDebt_aa3b4d9c-6d84-4bfd-a409-fa91532bc0b1" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/BorrowingsPrimeBrokerageCreditFacilitiesDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#BorrowingsPrimeBrokerageCreditFacilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/BorrowingsPrimeBrokerageCreditFacilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtLineItems_fcaed172-f4fd-4d6b-93a4-0828a0816880" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShortTermDebtLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShortTermDebtTable_8b2e0b2b-dc31-401f-be6b-d57913f981b3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShortTermDebtTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShortTermDebtLineItems_fcaed172-f4fd-4d6b-93a4-0828a0816880" xlink:to="loc_us-gaap_ScheduleOfShortTermDebtTable_8b2e0b2b-dc31-401f-be6b-d57913f981b3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_1e5d2ccc-bcd6-44e9-b095-9c389ddc92e2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShortTermDebtTable_8b2e0b2b-dc31-401f-be6b-d57913f981b3" xlink:to="loc_us-gaap_CreditFacilityAxis_1e5d2ccc-bcd6-44e9-b095-9c389ddc92e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_1e5d2ccc-bcd6-44e9-b095-9c389ddc92e2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_1e5d2ccc-bcd6-44e9-b095-9c389ddc92e2" xlink:to="loc_us-gaap_CreditFacilityDomain_1e5d2ccc-bcd6-44e9-b095-9c389ddc92e2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_2e6b7f60-84ec-4a21-a67a-998730ce38b9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_1e5d2ccc-bcd6-44e9-b095-9c389ddc92e2" xlink:to="loc_us-gaap_CreditFacilityDomain_2e6b7f60-84ec-4a21-a67a-998730ce38b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ShortTermCreditFacilitiesMember_ab02048f-88e4-4c2d-a795-df9be4839b49" xlink:href="virt-20240930.xsd#virt_ShortTermCreditFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_2e6b7f60-84ec-4a21-a67a-998730ce38b9" xlink:to="loc_virt_ShortTermCreditFacilitiesMember_ab02048f-88e4-4c2d-a795-df9be4839b49" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtWeightedAverageInterestRate_ced45a01-08c9-4f90-acf4-b1c38562b0d6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShortTermDebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_fcaed172-f4fd-4d6b-93a4-0828a0816880" xlink:to="loc_us-gaap_ShortTermDebtWeightedAverageInterestRate_ced45a01-08c9-4f90-acf4-b1c38562b0d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_dc404be4-f72c-4c74-b57c-4e389553554f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_fcaed172-f4fd-4d6b-93a4-0828a0816880" xlink:to="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_dc404be4-f72c-4c74-b57c-4e389553554f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_4cb7aac5-e2ee-49b7-950d-230eb8834be8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_fcaed172-f4fd-4d6b-93a4-0828a0816880" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_4cb7aac5-e2ee-49b7-950d-230eb8834be8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebt_1f3cf416-cf4e-4582-bcc8-6fc354e2eb77" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestExpenseDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_fcaed172-f4fd-4d6b-93a4-0828a0816880" xlink:to="loc_us-gaap_InterestExpenseDebt_1f3cf416-cf4e-4582-bcc8-6fc354e2eb77" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/BorrowingsLongTermBorrowingsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#BorrowingsLongTermBorrowingsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/BorrowingsLongTermBorrowingsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_aab4a395-fa14-4a8f-94c1-4e072bd65466" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_da33c972-b99c-4e48-9c96-dfb03883aff7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_aab4a395-fa14-4a8f-94c1-4e072bd65466" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_da33c972-b99c-4e48-9c96-dfb03883aff7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_ea366e33-75e5-44b5-8dbb-17e003013e4d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_da33c972-b99c-4e48-9c96-dfb03883aff7" xlink:to="loc_us-gaap_DebtInstrumentAxis_ea366e33-75e5-44b5-8dbb-17e003013e4d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_ea366e33-75e5-44b5-8dbb-17e003013e4d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_ea366e33-75e5-44b5-8dbb-17e003013e4d" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_ea366e33-75e5-44b5-8dbb-17e003013e4d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_4a1e06e4-a77b-41cb-9efb-64fa2458dee8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_ea366e33-75e5-44b5-8dbb-17e003013e4d" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_4a1e06e4-a77b-41cb-9efb-64fa2458dee8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SeniorSecuredCreditFacilityMember_3484c14a-3db8-4a70-b9dd-b76ee7c65416" xlink:href="virt-20240930.xsd#virt_SeniorSecuredCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4a1e06e4-a77b-41cb-9efb-64fa2458dee8" xlink:to="loc_virt_SeniorSecuredCreditFacilityMember_3484c14a-3db8-4a70-b9dd-b76ee7c65416" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_b3817ec3-fbf6-4f13-b5b0-6bf198ea1127" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_da33c972-b99c-4e48-9c96-dfb03883aff7" xlink:to="loc_us-gaap_CreditFacilityAxis_b3817ec3-fbf6-4f13-b5b0-6bf198ea1127" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_b3817ec3-fbf6-4f13-b5b0-6bf198ea1127_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_b3817ec3-fbf6-4f13-b5b0-6bf198ea1127" xlink:to="loc_us-gaap_CreditFacilityDomain_b3817ec3-fbf6-4f13-b5b0-6bf198ea1127_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_074034ef-1934-4620-8a2b-95b25a534ccf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_b3817ec3-fbf6-4f13-b5b0-6bf198ea1127" xlink:to="loc_us-gaap_CreditFacilityDomain_074034ef-1934-4620-8a2b-95b25a534ccf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SeniorSecuredSecondLienNotesMember_90e256c3-d134-4237-b560-4a8008bd6171" xlink:href="virt-20240930.xsd#virt_SeniorSecuredSecondLienNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_074034ef-1934-4620-8a2b-95b25a534ccf" xlink:to="loc_virt_SeniorSecuredSecondLienNotesMember_90e256c3-d134-4237-b560-4a8008bd6171" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SeniorSecuredFirstLienNotesMember_783195a3-305e-458f-882f-f36bd170001b" xlink:href="virt-20240930.xsd#virt_SeniorSecuredFirstLienNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_074034ef-1934-4620-8a2b-95b25a534ccf" xlink:to="loc_virt_SeniorSecuredFirstLienNotesMember_783195a3-305e-458f-882f-f36bd170001b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_93609edf-b05c-45e3-ac14-e8e19212fab2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_da33c972-b99c-4e48-9c96-dfb03883aff7" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_93609edf-b05c-45e3-ac14-e8e19212fab2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_93609edf-b05c-45e3-ac14-e8e19212fab2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_93609edf-b05c-45e3-ac14-e8e19212fab2" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_93609edf-b05c-45e3-ac14-e8e19212fab2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_2289c1bd-5ca0-41ea-bd2b-b89ae3f0c825" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_93609edf-b05c-45e3-ac14-e8e19212fab2" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_2289c1bd-5ca0-41ea-bd2b-b89ae3f0c825" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SeniorSecuredFirstLienTermLoanMember_1a3b78b9-5290-4fd3-9805-b877e0549767" xlink:href="virt-20240930.xsd#virt_SeniorSecuredFirstLienTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_2289c1bd-5ca0-41ea-bd2b-b89ae3f0c825" xlink:to="loc_virt_SeniorSecuredFirstLienTermLoanMember_1a3b78b9-5290-4fd3-9805-b877e0549767" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_9a8d4407-9dc7-481b-9b18-a40593954904" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_2289c1bd-5ca0-41ea-bd2b-b89ae3f0c825" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_9a8d4407-9dc7-481b-9b18-a40593954904" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_f89f52dc-2f9e-4498-962a-bb2a0ba405a8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_aab4a395-fa14-4a8f-94c1-4e072bd65466" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_f89f52dc-2f9e-4498-962a-bb2a0ba405a8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_83a9aa77-16da-4b1a-b0ce-bd66ee705ab0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_aab4a395-fa14-4a8f-94c1-4e072bd65466" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_83a9aa77-16da-4b1a-b0ce-bd66ee705ab0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_0399c084-197f-4453-b109-f4c7d7cc26c7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentUnamortizedDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_aab4a395-fa14-4a8f-94c1-4e072bd65466" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_0399c084-197f-4453-b109-f4c7d7cc26c7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_1eaac380-142f-4e19-843f-1e0d5dac5d0d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_aab4a395-fa14-4a8f-94c1-4e072bd65466" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_1eaac380-142f-4e19-843f-1e0d5dac5d0d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_ac1fd17a-11e1-4447-8c73-6ad8c3b90842" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_aab4a395-fa14-4a8f-94c1-4e072bd65466" xlink:to="loc_us-gaap_LongTermDebt_ac1fd17a-11e1-4447-8c73-6ad8c3b90842" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/BorrowingsCreditAgreementDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#BorrowingsCreditAgreementDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/BorrowingsCreditAgreementDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_5c554009-785a-4bf6-8c46-4b974c4fc719" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_us-gaap_DebtInstrumentTable_5c554009-785a-4bf6-8c46-4b974c4fc719" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_49a989d2-dbdc-4b79-8a66-38d4d0d7cf3b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5c554009-785a-4bf6-8c46-4b974c4fc719" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_49a989d2-dbdc-4b79-8a66-38d4d0d7cf3b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_49a989d2-dbdc-4b79-8a66-38d4d0d7cf3b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_49a989d2-dbdc-4b79-8a66-38d4d0d7cf3b" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_49a989d2-dbdc-4b79-8a66-38d4d0d7cf3b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_64ca83f1-7fc7-45b2-b9c9-ebe75bab6672" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_49a989d2-dbdc-4b79-8a66-38d4d0d7cf3b" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_64ca83f1-7fc7-45b2-b9c9-ebe75bab6672" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SeniorSecuredFirstLienTermLoanMember_225f9eee-7b5d-4783-9fe6-c1e3b454e7c6" xlink:href="virt-20240930.xsd#virt_SeniorSecuredFirstLienTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_64ca83f1-7fc7-45b2-b9c9-ebe75bab6672" xlink:to="loc_virt_SeniorSecuredFirstLienTermLoanMember_225f9eee-7b5d-4783-9fe6-c1e3b454e7c6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VFHParentLLCMember_ed26ce32-262a-4097-9477-268c62f6e1d1" xlink:href="virt-20240930.xsd#virt_VFHParentLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_64ca83f1-7fc7-45b2-b9c9-ebe75bab6672" xlink:to="loc_virt_VFHParentLLCMember_ed26ce32-262a-4097-9477-268c62f6e1d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_TermLoanMember_7531e95f-4ab5-40bf-a443-f9f547a3b322" xlink:href="virt-20240930.xsd#virt_TermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_64ca83f1-7fc7-45b2-b9c9-ebe75bab6672" xlink:to="loc_virt_TermLoanMember_7531e95f-4ab5-40bf-a443-f9f547a3b322" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_129571f6-d2f7-466e-9025-b85473a15bed" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_64ca83f1-7fc7-45b2-b9c9-ebe75bab6672" xlink:to="loc_us-gaap_LineOfCreditMember_129571f6-d2f7-466e-9025-b85473a15bed" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_b660c1e1-6bf8-453f-a8b6-3f1d27ccb63f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5c554009-785a-4bf6-8c46-4b974c4fc719" xlink:to="loc_us-gaap_DebtInstrumentAxis_b660c1e1-6bf8-453f-a8b6-3f1d27ccb63f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_b660c1e1-6bf8-453f-a8b6-3f1d27ccb63f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_b660c1e1-6bf8-453f-a8b6-3f1d27ccb63f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_b660c1e1-6bf8-453f-a8b6-3f1d27ccb63f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_2bc5d3af-3ce5-4c3d-aa36-714e4f643a41" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_b660c1e1-6bf8-453f-a8b6-3f1d27ccb63f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_2bc5d3af-3ce5-4c3d-aa36-714e4f643a41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_b1994e1b-9237-4fd6-a272-8d72b6972ce0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_2bc5d3af-3ce5-4c3d-aa36-714e4f643a41" xlink:to="loc_us-gaap_InterestRateSwapMember_b1994e1b-9237-4fd6-a272-8d72b6972ce0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_FirstLienNotesDue2031Member_3c25bfaf-9621-40bf-8c10-8b59c840e021" xlink:href="virt-20240930.xsd#virt_FirstLienNotesDue2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_2bc5d3af-3ce5-4c3d-aa36-714e4f643a41" xlink:to="loc_virt_FirstLienNotesDue2031Member_3c25bfaf-9621-40bf-8c10-8b59c840e021" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_59096fb3-7d53-43ea-a758-49374aa5fb44" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5c554009-785a-4bf6-8c46-4b974c4fc719" xlink:to="loc_dei_LegalEntityAxis_59096fb3-7d53-43ea-a758-49374aa5fb44" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_59096fb3-7d53-43ea-a758-49374aa5fb44_default" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_59096fb3-7d53-43ea-a758-49374aa5fb44" xlink:to="loc_dei_EntityDomain_59096fb3-7d53-43ea-a758-49374aa5fb44_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_7e8315a3-87f8-475f-aec7-e937a4e34ec1" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_59096fb3-7d53-43ea-a758-49374aa5fb44" xlink:to="loc_dei_EntityDomain_7e8315a3-87f8-475f-aec7-e937a4e34ec1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VFHParentLLCMember_5a21a9f0-b05e-4010-8667-bdf73d9c8031" xlink:href="virt-20240930.xsd#virt_VFHParentLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_7e8315a3-87f8-475f-aec7-e937a4e34ec1" xlink:to="loc_virt_VFHParentLLCMember_5a21a9f0-b05e-4010-8667-bdf73d9c8031" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_e7b910fb-cd03-419a-b92e-0b94fb132202" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5c554009-785a-4bf6-8c46-4b974c4fc719" xlink:to="loc_us-gaap_CreditFacilityAxis_e7b910fb-cd03-419a-b92e-0b94fb132202" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_e7b910fb-cd03-419a-b92e-0b94fb132202_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_e7b910fb-cd03-419a-b92e-0b94fb132202" xlink:to="loc_us-gaap_CreditFacilityDomain_e7b910fb-cd03-419a-b92e-0b94fb132202_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_b6f4eff4-1a77-4494-99a6-5ee88c3e5aae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_e7b910fb-cd03-419a-b92e-0b94fb132202" xlink:to="loc_us-gaap_CreditFacilityDomain_b6f4eff4-1a77-4494-99a6-5ee88c3e5aae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_57ff86e3-ab57-4e57-83b7-4a6017519d76" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b6f4eff4-1a77-4494-99a6-5ee88c3e5aae" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_57ff86e3-ab57-4e57-83b7-4a6017519d76" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_11505e90-7bc9-4d32-9569-8be6de61d7e5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b6f4eff4-1a77-4494-99a6-5ee88c3e5aae" xlink:to="loc_us-gaap_LetterOfCreditMember_11505e90-7bc9-4d32-9569-8be6de61d7e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SwinglineSubfacilityMember_d3c00bef-e1b2-4151-9f38-da32496739ce" xlink:href="virt-20240930.xsd#virt_SwinglineSubfacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b6f4eff4-1a77-4494-99a6-5ee88c3e5aae" xlink:to="loc_virt_SwinglineSubfacilityMember_d3c00bef-e1b2-4151-9f38-da32496739ce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_AmendedCreditAgreementMember_0db33fd3-46c4-498d-bc94-5fb10cff9e55" xlink:href="virt-20240930.xsd#virt_AmendedCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b6f4eff4-1a77-4494-99a6-5ee88c3e5aae" xlink:to="loc_virt_AmendedCreditAgreementMember_0db33fd3-46c4-498d-bc94-5fb10cff9e55" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SeniorSecuredFirstLienTermLoanMember_b6b0993b-6e52-4b46-b496-ecc24120c6a4" xlink:href="virt-20240930.xsd#virt_SeniorSecuredFirstLienTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b6f4eff4-1a77-4494-99a6-5ee88c3e5aae" xlink:to="loc_virt_SeniorSecuredFirstLienTermLoanMember_b6b0993b-6e52-4b46-b496-ecc24120c6a4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SeniorSecuredSecondLienNotesMember_4c063016-9dad-44bc-9494-52fc9e37a964" xlink:href="virt-20240930.xsd#virt_SeniorSecuredSecondLienNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b6f4eff4-1a77-4494-99a6-5ee88c3e5aae" xlink:to="loc_virt_SeniorSecuredSecondLienNotesMember_4c063016-9dad-44bc-9494-52fc9e37a964" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_93cdc781-0a3b-4d40-8d04-4ad0538eed04" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b6f4eff4-1a77-4494-99a6-5ee88c3e5aae" xlink:to="loc_us-gaap_LineOfCreditMember_93cdc781-0a3b-4d40-8d04-4ad0538eed04" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SeniorSecuredCreditFacilityMember_67eb7b78-d02c-49f2-b339-30c305acec09" xlink:href="virt-20240930.xsd#virt_SeniorSecuredCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b6f4eff4-1a77-4494-99a6-5ee88c3e5aae" xlink:to="loc_virt_SeniorSecuredCreditFacilityMember_67eb7b78-d02c-49f2-b339-30c305acec09" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_e0b9c960-d8d8-45eb-a545-403348240c6d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b6f4eff4-1a77-4494-99a6-5ee88c3e5aae" xlink:to="loc_us-gaap_SecuredDebtMember_e0b9c960-d8d8-45eb-a545-403348240c6d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_FirstLienTermLoanFacilityMember_977cd344-a578-4ee2-a5fb-7e41659056c4" xlink:href="virt-20240930.xsd#virt_FirstLienTermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b6f4eff4-1a77-4494-99a6-5ee88c3e5aae" xlink:to="loc_virt_FirstLienTermLoanFacilityMember_977cd344-a578-4ee2-a5fb-7e41659056c4" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_1baa3811-94f4-41e3-98c4-e59bade876fd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5c554009-785a-4bf6-8c46-4b974c4fc719" xlink:to="loc_us-gaap_VariableRateAxis_1baa3811-94f4-41e3-98c4-e59bade876fd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_1baa3811-94f4-41e3-98c4-e59bade876fd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_1baa3811-94f4-41e3-98c4-e59bade876fd" xlink:to="loc_us-gaap_VariableRateDomain_1baa3811-94f4-41e3-98c4-e59bade876fd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_47c9f91b-8f87-4b91-8e85-115bbf8951fb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_1baa3811-94f4-41e3-98c4-e59bade876fd" xlink:to="loc_us-gaap_VariableRateDomain_47c9f91b-8f87-4b91-8e85-115bbf8951fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_OvernightBankFundingRateMember_ee29d986-bcd0-4fcf-84b2-285bbdba81c2" xlink:href="virt-20240930.xsd#virt_OvernightBankFundingRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_47c9f91b-8f87-4b91-8e85-115bbf8951fb" xlink:to="loc_virt_OvernightBankFundingRateMember_ee29d986-bcd0-4fcf-84b2-285bbdba81c2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_72e00e0e-87c2-4b75-87b7-09182fdc3b08" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuredOvernightFinancingRateSofrMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_47c9f91b-8f87-4b91-8e85-115bbf8951fb" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_72e00e0e-87c2-4b75-87b7-09182fdc3b08" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VariableRateComponentAxis_b75f9f38-7eae-452c-8c57-a51a601bceae" xlink:href="virt-20240930.xsd#virt_VariableRateComponentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5c554009-785a-4bf6-8c46-4b974c4fc719" xlink:to="loc_virt_VariableRateComponentAxis_b75f9f38-7eae-452c-8c57-a51a601bceae" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VariableRateScenarioDomain_b75f9f38-7eae-452c-8c57-a51a601bceae_default" xlink:href="virt-20240930.xsd#virt_VariableRateScenarioDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_virt_VariableRateComponentAxis_b75f9f38-7eae-452c-8c57-a51a601bceae" xlink:to="loc_virt_VariableRateScenarioDomain_b75f9f38-7eae-452c-8c57-a51a601bceae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VariableRateScenarioDomain_ac9a7eef-0244-44ee-af76-9be4435c4e2a" xlink:href="virt-20240930.xsd#virt_VariableRateScenarioDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_virt_VariableRateComponentAxis_b75f9f38-7eae-452c-8c57-a51a601bceae" xlink:to="loc_virt_VariableRateScenarioDomain_ac9a7eef-0244-44ee-af76-9be4435c4e2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VariableRateScenario1Member_75a26b5c-a8d1-46ac-a4f2-3f71d09bec1c" xlink:href="virt-20240930.xsd#virt_VariableRateScenario1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_VariableRateScenarioDomain_ac9a7eef-0244-44ee-af76-9be4435c4e2a" xlink:to="loc_virt_VariableRateScenario1Member_75a26b5c-a8d1-46ac-a4f2-3f71d09bec1c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VariableRateScenario2Member_2cf3c7fc-c71f-43b0-a6fa-acbc9fe7fcdc" xlink:href="virt-20240930.xsd#virt_VariableRateScenario2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_VariableRateScenarioDomain_ac9a7eef-0244-44ee-af76-9be4435c4e2a" xlink:to="loc_virt_VariableRateScenario2Member_2cf3c7fc-c71f-43b0-a6fa-acbc9fe7fcdc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VariableRateComponentOneMember_d4311180-1b38-4f2a-8b36-682a2febc7d1" xlink:href="virt-20240930.xsd#virt_VariableRateComponentOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_VariableRateScenarioDomain_ac9a7eef-0244-44ee-af76-9be4435c4e2a" xlink:to="loc_virt_VariableRateComponentOneMember_d4311180-1b38-4f2a-8b36-682a2febc7d1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VariableRateComponentTwoMember_80f2ef2b-6dbf-4845-a4fb-09a07a1d23e2" xlink:href="virt-20240930.xsd#virt_VariableRateComponentTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_VariableRateScenarioDomain_ac9a7eef-0244-44ee-af76-9be4435c4e2a" xlink:to="loc_virt_VariableRateComponentTwoMember_80f2ef2b-6dbf-4845-a4fb-09a07a1d23e2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_8079ec9c-a8b0-4e2a-9846-1caad62ef9a8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5c554009-785a-4bf6-8c46-4b974c4fc719" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_8079ec9c-a8b0-4e2a-9846-1caad62ef9a8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_8079ec9c-a8b0-4e2a-9846-1caad62ef9a8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_8079ec9c-a8b0-4e2a-9846-1caad62ef9a8" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_8079ec9c-a8b0-4e2a-9846-1caad62ef9a8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_e73679ee-df6c-4ee4-91db-bdfb4c251c2f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_8079ec9c-a8b0-4e2a-9846-1caad62ef9a8" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_e73679ee-df6c-4ee4-91db-bdfb4c251c2f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_88dc2c42-eb6e-4516-90c0-b4736317baab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_e73679ee-df6c-4ee4-91db-bdfb4c251c2f" xlink:to="loc_us-gaap_InterestRateSwapMember_88dc2c42-eb6e-4516-90c0-b4736317baab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_January2020InterestRateSwapMember_6d3b5194-b95e-42a8-bcb5-6327b7ce4307" xlink:href="virt-20240930.xsd#virt_January2020InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_e73679ee-df6c-4ee4-91db-bdfb4c251c2f" xlink:to="loc_virt_January2020InterestRateSwapMember_6d3b5194-b95e-42a8-bcb5-6327b7ce4307" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_December2023InterestRateSwapMember_108b9614-6c89-4e18-bdb7-19dcbb70fc0d" xlink:href="virt-20240930.xsd#virt_December2023InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_e73679ee-df6c-4ee4-91db-bdfb4c251c2f" xlink:to="loc_virt_December2023InterestRateSwapMember_108b9614-6c89-4e18-bdb7-19dcbb70fc0d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_June2024InterestRateSwapMember_2d77d2c6-79bb-42f6-ad3d-086ff4f1bf2e" xlink:href="virt-20240930.xsd#virt_June2024InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_e73679ee-df6c-4ee4-91db-bdfb4c251c2f" xlink:to="loc_virt_June2024InterestRateSwapMember_2d77d2c6-79bb-42f6-ad3d-086ff4f1bf2e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_35da1bb3-2dc4-41a2-9703-fa2fe303ec2a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5c554009-785a-4bf6-8c46-4b974c4fc719" xlink:to="loc_srt_RangeAxis_35da1bb3-2dc4-41a2-9703-fa2fe303ec2a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_35da1bb3-2dc4-41a2-9703-fa2fe303ec2a_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_35da1bb3-2dc4-41a2-9703-fa2fe303ec2a" xlink:to="loc_srt_RangeMember_35da1bb3-2dc4-41a2-9703-fa2fe303ec2a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_86ee12bd-c28d-40af-ab77-3a64631c76da" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_35da1bb3-2dc4-41a2-9703-fa2fe303ec2a" xlink:to="loc_srt_RangeMember_86ee12bd-c28d-40af-ab77-3a64631c76da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_ad3aea17-1874-467e-b301-84f60881819e" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_86ee12bd-c28d-40af-ab77-3a64631c76da" xlink:to="loc_srt_MinimumMember_ad3aea17-1874-467e-b301-84f60881819e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_85701c62-38fa-491a-9318-f468388b773b" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_86ee12bd-c28d-40af-ab77-3a64631c76da" xlink:to="loc_srt_MaximumMember_85701c62-38fa-491a-9318-f468388b773b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_5e17b5db-4c3e-451a-af61-911e4618aff2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_5e17b5db-4c3e-451a-af61-911e4618aff2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_6f9888fb-f4ac-4bcf-8a8b-b049c98b5f43" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_6f9888fb-f4ac-4bcf-8a8b-b049c98b5f43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_56a80ff9-bb01-4b1d-b43f-b5bc398fefb2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_56a80ff9-bb01-4b1d-b43f-b5bc398fefb2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_f2244379-5442-447b-9e51-ca5aef0911eb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_f2244379-5442-447b-9e51-ca5aef0911eb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_LineOfCreditFacilityUnusedCapacityStepdownInCommitmentFeePercentage_507baefc-db31-4ed7-a521-9b5e4365b579" xlink:href="virt-20240930.xsd#virt_LineOfCreditFacilityUnusedCapacityStepdownInCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_virt_LineOfCreditFacilityUnusedCapacityStepdownInCommitmentFeePercentage_507baefc-db31-4ed7-a521-9b5e4365b579" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_DebtAmortizationPercentageOfAggregatePrincipalAmount_16eae7a4-e576-430d-82a0-b4002a1094f1" xlink:href="virt-20240930.xsd#virt_DebtAmortizationPercentageOfAggregatePrincipalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_virt_DebtAmortizationPercentageOfAggregatePrincipalAmount_16eae7a4-e576-430d-82a0-b4002a1094f1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfDebt_484fc1b2-b019-4789-b5a2-7cfaa17949cf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RepaymentsOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_us-gaap_RepaymentsOfDebt_484fc1b2-b019-4789-b5a2-7cfaa17949cf" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTermOfContract_8b026f3d-83f5-4ca7-93f8-c5e421152141" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_us-gaap_DerivativeTermOfContract_8b026f3d-83f5-4ca7-93f8-c5e421152141" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_d010714a-9833-492d-bfb3-43b51ec57dbd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_us-gaap_DerivativeNotionalAmount_d010714a-9833-492d-bfb3-43b51ec57dbd" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_1fd6da22-a52c-41dc-9034-2e405f311259" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeNumberOfInstrumentsHeld"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_1fd6da22-a52c-41dc-9034-2e405f311259" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFixedInterestRate_5dd0cfe0-8146-4677-ae9c-02a90b12dd25" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeFixedInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_us-gaap_DerivativeFixedInterestRate_5dd0cfe0-8146-4677-ae9c-02a90b12dd25" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations_8d709191-c579-4733-aca6-1441fc909830" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations_8d709191-c579-4733-aca6-1441fc909830" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_75fdb67d-a9a0-4640-afca-d3370692aa84" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_75fdb67d-a9a0-4640-afca-d3370692aa84" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_DebtInstrumentAdditionalBasisSpreadOnVariableRate_a49ec73b-ee15-40fc-985e-3852a6354209" xlink:href="virt-20240930.xsd#virt_DebtInstrumentAdditionalBasisSpreadOnVariableRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_virt_DebtInstrumentAdditionalBasisSpreadOnVariableRate_a49ec73b-ee15-40fc-985e-3852a6354209" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_PercentageOfPeriodicPayment_5c59b73c-1506-4075-81bc-84300790dfdc" xlink:href="virt-20240930.xsd#virt_PercentageOfPeriodicPayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_virt_PercentageOfPeriodicPayment_5c59b73c-1506-4075-81bc-84300790dfdc" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermBorrowings_e548d6e0-897f-4b69-9d86-4dc96c0b8d8b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShortTermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_us-gaap_ShortTermBorrowings_e548d6e0-897f-4b69-9d86-4dc96c0b8d8b" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTaxRelatedToPartialDedesignation_21d54bb0-08d2-4af1-a3ee-f00c8e822060" xlink:href="virt-20240930.xsd#virt_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTaxRelatedToPartialDedesignation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_09854dcf-f593-424d-8546-f85b9692a4c7" xlink:to="loc_virt_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTaxRelatedToPartialDedesignation_21d54bb0-08d2-4af1-a3ee-f00c8e822060" xlink:type="arc" order="16"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/BorrowingsSeniorSecuredFirstLienNotesDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#BorrowingsSeniorSecuredFirstLienNotesDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/BorrowingsSeniorSecuredFirstLienNotesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_a5e2f8d2-622e-428f-a257-4946e33f38f0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_6a0652dc-5154-4254-81f7-885ed9765814" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a5e2f8d2-622e-428f-a257-4946e33f38f0" xlink:to="loc_us-gaap_DebtInstrumentTable_6a0652dc-5154-4254-81f7-885ed9765814" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_953487f0-12dd-4fb2-90cc-03a48de6b576" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6a0652dc-5154-4254-81f7-885ed9765814" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_953487f0-12dd-4fb2-90cc-03a48de6b576" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_953487f0-12dd-4fb2-90cc-03a48de6b576_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_953487f0-12dd-4fb2-90cc-03a48de6b576" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_953487f0-12dd-4fb2-90cc-03a48de6b576_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_bfed63fc-83da-4aff-ba35-9fc32caed9c4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_953487f0-12dd-4fb2-90cc-03a48de6b576" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_bfed63fc-83da-4aff-ba35-9fc32caed9c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SeniorSecuredFirstLienTermLoanMember_0963f107-69d0-4775-a9ec-b29ccea9e340" xlink:href="virt-20240930.xsd#virt_SeniorSecuredFirstLienTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_bfed63fc-83da-4aff-ba35-9fc32caed9c4" xlink:to="loc_virt_SeniorSecuredFirstLienTermLoanMember_0963f107-69d0-4775-a9ec-b29ccea9e340" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_a82b6ffd-be3f-458d-919d-f2f5d6ac6a3a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_bfed63fc-83da-4aff-ba35-9fc32caed9c4" xlink:to="loc_us-gaap_LineOfCreditMember_a82b6ffd-be3f-458d-919d-f2f5d6ac6a3a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_679f8403-c05b-42e6-9747-dd7dcd5e6582" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_bfed63fc-83da-4aff-ba35-9fc32caed9c4" xlink:to="loc_us-gaap_SeniorNotesMember_679f8403-c05b-42e6-9747-dd7dcd5e6582" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_876074e7-ad92-4da0-aefe-8f0e776c4c02" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6a0652dc-5154-4254-81f7-885ed9765814" xlink:to="loc_us-gaap_DebtInstrumentAxis_876074e7-ad92-4da0-aefe-8f0e776c4c02" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_876074e7-ad92-4da0-aefe-8f0e776c4c02_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_876074e7-ad92-4da0-aefe-8f0e776c4c02" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_876074e7-ad92-4da0-aefe-8f0e776c4c02_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_e2196308-8e81-4b84-bc91-fd9287796206" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_876074e7-ad92-4da0-aefe-8f0e776c4c02" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_e2196308-8e81-4b84-bc91-fd9287796206" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_FirstLienNotesDue2031Member_6e18756a-4dc2-4290-b53b-1eeb879ff411" xlink:href="virt-20240930.xsd#virt_FirstLienNotesDue2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e2196308-8e81-4b84-bc91-fd9287796206" xlink:to="loc_virt_FirstLienNotesDue2031Member_6e18756a-4dc2-4290-b53b-1eeb879ff411" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_IncrementalTermLoansMember_9030d297-151d-4475-8133-cd33c21a1c1f" xlink:href="virt-20240930.xsd#virt_IncrementalTermLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e2196308-8e81-4b84-bc91-fd9287796206" xlink:to="loc_virt_IncrementalTermLoansMember_9030d297-151d-4475-8133-cd33c21a1c1f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_5dfff5df-2f38-4e1d-85f2-07f14935d44f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6a0652dc-5154-4254-81f7-885ed9765814" xlink:to="loc_us-gaap_CreditFacilityAxis_5dfff5df-2f38-4e1d-85f2-07f14935d44f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_5dfff5df-2f38-4e1d-85f2-07f14935d44f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_5dfff5df-2f38-4e1d-85f2-07f14935d44f" xlink:to="loc_us-gaap_CreditFacilityDomain_5dfff5df-2f38-4e1d-85f2-07f14935d44f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_327991a0-7d12-449a-9db0-ac49b1413289" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_5dfff5df-2f38-4e1d-85f2-07f14935d44f" xlink:to="loc_us-gaap_CreditFacilityDomain_327991a0-7d12-449a-9db0-ac49b1413289" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SeniorSecuredFirstLienTermLoanMember_b0012e47-0e7b-4242-a578-aff62f5772ee" xlink:href="virt-20240930.xsd#virt_SeniorSecuredFirstLienTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_327991a0-7d12-449a-9db0-ac49b1413289" xlink:to="loc_virt_SeniorSecuredFirstLienTermLoanMember_b0012e47-0e7b-4242-a578-aff62f5772ee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_16d56a85-c486-41fc-89d5-b51ffc8d97c0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_327991a0-7d12-449a-9db0-ac49b1413289" xlink:to="loc_us-gaap_LineOfCreditMember_16d56a85-c486-41fc-89d5-b51ffc8d97c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RedemptionScenarioAxis_957e1334-5635-42e7-84c7-1909b8e4be90" xlink:href="virt-20240930.xsd#virt_RedemptionScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6a0652dc-5154-4254-81f7-885ed9765814" xlink:to="loc_virt_RedemptionScenarioAxis_957e1334-5635-42e7-84c7-1909b8e4be90" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RedemptionScenarioDomain_957e1334-5635-42e7-84c7-1909b8e4be90_default" xlink:href="virt-20240930.xsd#virt_RedemptionScenarioDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_virt_RedemptionScenarioAxis_957e1334-5635-42e7-84c7-1909b8e4be90" xlink:to="loc_virt_RedemptionScenarioDomain_957e1334-5635-42e7-84c7-1909b8e4be90_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RedemptionScenarioDomain_f84dfe66-e690-4ba4-927c-0de33c26ed30" xlink:href="virt-20240930.xsd#virt_RedemptionScenarioDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_virt_RedemptionScenarioAxis_957e1334-5635-42e7-84c7-1909b8e4be90" xlink:to="loc_virt_RedemptionScenarioDomain_f84dfe66-e690-4ba4-927c-0de33c26ed30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_DebtRedemptionPriorToJune152027Member_55245005-d0b9-4975-8aee-aa751da99c80" xlink:href="virt-20240930.xsd#virt_DebtRedemptionPriorToJune152027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_RedemptionScenarioDomain_f84dfe66-e690-4ba4-927c-0de33c26ed30" xlink:to="loc_virt_DebtRedemptionPriorToJune152027Member_55245005-d0b9-4975-8aee-aa751da99c80" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_fa52fe0e-698f-4f49-9c3b-f7ebe532436b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6a0652dc-5154-4254-81f7-885ed9765814" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_fa52fe0e-698f-4f49-9c3b-f7ebe532436b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_fa52fe0e-698f-4f49-9c3b-f7ebe532436b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_fa52fe0e-698f-4f49-9c3b-f7ebe532436b" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_fa52fe0e-698f-4f49-9c3b-f7ebe532436b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_fe676f5f-1dc3-400d-8c12-96cf3c4326d9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_fa52fe0e-698f-4f49-9c3b-f7ebe532436b" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_fe676f5f-1dc3-400d-8c12-96cf3c4326d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_b56ed6e6-77b5-4d5a-9cc2-1eefdb1c3b8e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_fe676f5f-1dc3-400d-8c12-96cf3c4326d9" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_b56ed6e6-77b5-4d5a-9cc2-1eefdb1c3b8e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_915a6752-b3a7-4fce-b1a3-a9f11e1c99bf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_fe676f5f-1dc3-400d-8c12-96cf3c4326d9" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_915a6752-b3a7-4fce-b1a3-a9f11e1c99bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodThreeMember_85c70d78-eac6-4eb3-b92f-de592a91634c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_fe676f5f-1dc3-400d-8c12-96cf3c4326d9" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodThreeMember_85c70d78-eac6-4eb3-b92f-de592a91634c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodFourMember_c03a5110-c004-4fca-b6f9-fdb242a42660" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_fe676f5f-1dc3-400d-8c12-96cf3c4326d9" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodFourMember_c03a5110-c004-4fca-b6f9-fdb242a42660" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_83fbe39e-aa3c-4711-853b-1833d0ef481d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a5e2f8d2-622e-428f-a257-4946e33f38f0" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_83fbe39e-aa3c-4711-853b-1833d0ef481d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_454b0a34-df68-47e7-806f-cca522588ff6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a5e2f8d2-622e-428f-a257-4946e33f38f0" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_454b0a34-df68-47e7-806f-cca522588ff6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_DebtInstrumentCollateralPercentageOfNonVotingCapitalStockOfMaterialFirstTierForeignSubsidiaries_38928b56-be35-463f-bb41-f1d50eee920d" xlink:href="virt-20240930.xsd#virt_DebtInstrumentCollateralPercentageOfNonVotingCapitalStockOfMaterialFirstTierForeignSubsidiaries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a5e2f8d2-622e-428f-a257-4946e33f38f0" xlink:to="loc_virt_DebtInstrumentCollateralPercentageOfNonVotingCapitalStockOfMaterialFirstTierForeignSubsidiaries_38928b56-be35-463f-bb41-f1d50eee920d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_DebtInstrumentCollateralPercentageOfCapitalStockOfMaterialFirstTierForeignSubsidiaries_e5f087b5-fbdf-4a62-b694-ff6729b0becb" xlink:href="virt-20240930.xsd#virt_DebtInstrumentCollateralPercentageOfCapitalStockOfMaterialFirstTierForeignSubsidiaries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a5e2f8d2-622e-428f-a257-4946e33f38f0" xlink:to="loc_virt_DebtInstrumentCollateralPercentageOfCapitalStockOfMaterialFirstTierForeignSubsidiaries_e5f087b5-fbdf-4a62-b694-ff6729b0becb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_76bcdd53-91f6-48da-96fd-5a2eb1d93150" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a5e2f8d2-622e-428f-a257-4946e33f38f0" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_76bcdd53-91f6-48da-96fd-5a2eb1d93150" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed_cdc3cfd5-25e1-4bcd-96fc-4d4e154669e5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a5e2f8d2-622e-428f-a257-4946e33f38f0" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed_cdc3cfd5-25e1-4bcd-96fc-4d4e154669e5" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/BorrowingsScheduleofRedemptionPricesDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#BorrowingsScheduleofRedemptionPricesDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/BorrowingsScheduleofRedemptionPricesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_f80cf7a8-8456-4b75-8156-85c3ce2646cb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_72f18205-a098-4fc9-90a2-5b7eeeccead6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_f80cf7a8-8456-4b75-8156-85c3ce2646cb" xlink:to="loc_us-gaap_DebtInstrumentTable_72f18205-a098-4fc9-90a2-5b7eeeccead6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RedemptionScenarioAxis_f012f82c-84ef-43a6-8c82-8c8d4c8a1315" xlink:href="virt-20240930.xsd#virt_RedemptionScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_72f18205-a098-4fc9-90a2-5b7eeeccead6" xlink:to="loc_virt_RedemptionScenarioAxis_f012f82c-84ef-43a6-8c82-8c8d4c8a1315" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RedemptionScenarioDomain_f012f82c-84ef-43a6-8c82-8c8d4c8a1315_default" xlink:href="virt-20240930.xsd#virt_RedemptionScenarioDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_virt_RedemptionScenarioAxis_f012f82c-84ef-43a6-8c82-8c8d4c8a1315" xlink:to="loc_virt_RedemptionScenarioDomain_f012f82c-84ef-43a6-8c82-8c8d4c8a1315_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RedemptionScenarioDomain_f2987f8b-eb4a-4d0f-b50c-05ca743c2cf0" xlink:href="virt-20240930.xsd#virt_RedemptionScenarioDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_virt_RedemptionScenarioAxis_f012f82c-84ef-43a6-8c82-8c8d4c8a1315" xlink:to="loc_virt_RedemptionScenarioDomain_f2987f8b-eb4a-4d0f-b50c-05ca743c2cf0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_DebtRedemptionPriorToJune152027Member_a678fe9a-2b4c-4169-a6ba-4ff70aa98b7e" xlink:href="virt-20240930.xsd#virt_DebtRedemptionPriorToJune152027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_RedemptionScenarioDomain_f2987f8b-eb4a-4d0f-b50c-05ca743c2cf0" xlink:to="loc_virt_DebtRedemptionPriorToJune152027Member_a678fe9a-2b4c-4169-a6ba-4ff70aa98b7e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_50e99942-e649-43bc-96a3-be32da8ec0ba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_72f18205-a098-4fc9-90a2-5b7eeeccead6" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_50e99942-e649-43bc-96a3-be32da8ec0ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_50e99942-e649-43bc-96a3-be32da8ec0ba_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_50e99942-e649-43bc-96a3-be32da8ec0ba" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_50e99942-e649-43bc-96a3-be32da8ec0ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_e3b9e69a-6258-476d-a8b9-bd470b1dad5c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_50e99942-e649-43bc-96a3-be32da8ec0ba" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_e3b9e69a-6258-476d-a8b9-bd470b1dad5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_3784d092-84d3-4746-a98f-f3f292674c89" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_e3b9e69a-6258-476d-a8b9-bd470b1dad5c" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_3784d092-84d3-4746-a98f-f3f292674c89" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_377de4cd-07a9-44a3-8881-135674122520" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_e3b9e69a-6258-476d-a8b9-bd470b1dad5c" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_377de4cd-07a9-44a3-8881-135674122520" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodThreeMember_ac22f6a8-8856-430b-910b-4d9c28289e51" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPeriodThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_e3b9e69a-6258-476d-a8b9-bd470b1dad5c" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodThreeMember_ac22f6a8-8856-430b-910b-4d9c28289e51" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed_b5c897c4-80ac-478b-a295-ce250a88e56d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_f80cf7a8-8456-4b75-8156-85c3ce2646cb" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed_b5c897c4-80ac-478b-a295-ce250a88e56d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/BorrowingsSBIBondsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#BorrowingsSBIBondsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/BorrowingsSBIBondsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_5686abc8-9b9f-4f80-8972-0865e1450a18" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_c8311ecd-9fe4-4d41-8657-3f4b4a5760f1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_5686abc8-9b9f-4f80-8972-0865e1450a18" xlink:to="loc_us-gaap_DebtInstrumentTable_c8311ecd-9fe4-4d41-8657-3f4b4a5760f1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_3c126999-bb08-42ee-ad8a-b49efe698a7c" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_c8311ecd-9fe4-4d41-8657-3f4b4a5760f1" xlink:to="loc_dei_LegalEntityAxis_3c126999-bb08-42ee-ad8a-b49efe698a7c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_3c126999-bb08-42ee-ad8a-b49efe698a7c_default" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_3c126999-bb08-42ee-ad8a-b49efe698a7c" xlink:to="loc_dei_EntityDomain_3c126999-bb08-42ee-ad8a-b49efe698a7c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_b9233c9c-ac78-40b5-b847-6ce07363f91b" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_3c126999-bb08-42ee-ad8a-b49efe698a7c" xlink:to="loc_dei_EntityDomain_b9233c9c-ac78-40b5-b847-6ce07363f91b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VFHParentLLCMember_c66db7c7-0742-4c36-a2b5-9c41abd30707" xlink:href="virt-20240930.xsd#virt_VFHParentLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_b9233c9c-ac78-40b5-b847-6ce07363f91b" xlink:to="loc_virt_VFHParentLLCMember_c66db7c7-0742-4c36-a2b5-9c41abd30707" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_db07d8dd-ce5a-4678-9df3-234b2b87c9d2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_c8311ecd-9fe4-4d41-8657-3f4b4a5760f1" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_db07d8dd-ce5a-4678-9df3-234b2b87c9d2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_db07d8dd-ce5a-4678-9df3-234b2b87c9d2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_db07d8dd-ce5a-4678-9df3-234b2b87c9d2" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_db07d8dd-ce5a-4678-9df3-234b2b87c9d2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_fee54338-bf75-4614-bdaa-7792c0268c6f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_db07d8dd-ce5a-4678-9df3-234b2b87c9d2" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_fee54338-bf75-4614-bdaa-7792c0268c6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_1c85ea8b-784e-4559-8cb1-12ad71ca2eaa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_fee54338-bf75-4614-bdaa-7792c0268c6f" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_1c85ea8b-784e-4559-8cb1-12ad71ca2eaa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_baebbb1c-9d7c-44ee-ad80-8ed703b9ea35" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_c8311ecd-9fe4-4d41-8657-3f4b4a5760f1" xlink:to="loc_us-gaap_DebtInstrumentAxis_baebbb1c-9d7c-44ee-ad80-8ed703b9ea35" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_baebbb1c-9d7c-44ee-ad80-8ed703b9ea35_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_baebbb1c-9d7c-44ee-ad80-8ed703b9ea35" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_baebbb1c-9d7c-44ee-ad80-8ed703b9ea35_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_60058611-28f8-4c4e-9080-c3f048cfc578" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_baebbb1c-9d7c-44ee-ad80-8ed703b9ea35" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_60058611-28f8-4c4e-9080-c3f048cfc578" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SBIBondsMember_87f55c7f-72f5-4645-8213-08b8e10dc12a" xlink:href="virt-20240930.xsd#virt_SBIBondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_60058611-28f8-4c4e-9080-c3f048cfc578" xlink:to="loc_virt_SBIBondsMember_87f55c7f-72f5-4645-8213-08b8e10dc12a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_847ba8a4-aae6-47b7-b0d0-e1fae267dc9b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_5686abc8-9b9f-4f80-8972-0865e1450a18" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_847ba8a4-aae6-47b7-b0d0-e1fae267dc9b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_15183bdf-9bdb-4521-bd4b-2251824e2348" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_5686abc8-9b9f-4f80-8972-0865e1450a18" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_15183bdf-9bdb-4521-bd4b-2251824e2348" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossRealized_cb4a60dc-772a-4657-99d7-30820977c231" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignCurrencyTransactionGainLossRealized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_5686abc8-9b9f-4f80-8972-0865e1450a18" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossRealized_cb4a60dc-772a-4657-99d7-30820977c231" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/FinancialAssetsandLiabilitiesMeasuredonaRecurringBasisDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#FinancialAssetsandLiabilitiesMeasuredonaRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/FinancialAssetsandLiabilitiesMeasuredonaRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_d6e3ec67-19f5-4c9f-9eed-7ebbefc4f6ae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c9af2458-3ac0-451c-9c3e-4d4b95a96a6b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_d6e3ec67-19f5-4c9f-9eed-7ebbefc4f6ae" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c9af2458-3ac0-451c-9c3e-4d4b95a96a6b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_75cc1383-aaf5-4c0c-8c59-ad30e043f000" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c9af2458-3ac0-451c-9c3e-4d4b95a96a6b" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_75cc1383-aaf5-4c0c-8c59-ad30e043f000" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_75cc1383-aaf5-4c0c-8c59-ad30e043f000_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_75cc1383-aaf5-4c0c-8c59-ad30e043f000" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_75cc1383-aaf5-4c0c-8c59-ad30e043f000_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0e9e86ad-9e23-4838-b708-2745cd4720cc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_75cc1383-aaf5-4c0c-8c59-ad30e043f000" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0e9e86ad-9e23-4838-b708-2745cd4720cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_4c094506-0ce9-4ccd-91b3-16c01a39a77b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0e9e86ad-9e23-4838-b708-2745cd4720cc" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_4c094506-0ce9-4ccd-91b3-16c01a39a77b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_25083027-9fd0-4a68-8641-b2a9e5d73fa8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0e9e86ad-9e23-4838-b708-2745cd4720cc" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_25083027-9fd0-4a68-8641-b2a9e5d73fa8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_c0f1a9d2-3377-48fa-9798-523679fb9211" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0e9e86ad-9e23-4838-b708-2745cd4720cc" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_c0f1a9d2-3377-48fa-9798-523679fb9211" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_893f8a79-0332-412c-b41c-2e08b81820c2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c9af2458-3ac0-451c-9c3e-4d4b95a96a6b" xlink:to="loc_us-gaap_FinancialInstrumentAxis_893f8a79-0332-412c-b41c-2e08b81820c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_893f8a79-0332-412c-b41c-2e08b81820c2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_893f8a79-0332-412c-b41c-2e08b81820c2" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_893f8a79-0332-412c-b41c-2e08b81820c2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_16f7bfd8-f141-44fd-8575-c0b6b8d35d40" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_893f8a79-0332-412c-b41c-2e08b81820c2" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_16f7bfd8-f141-44fd-8575-c0b6b8d35d40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesMember_b2f3224c-7f49-4069-850a-88a6161a4e02" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_16f7bfd8-f141-44fd-8575-c0b6b8d35d40" xlink:to="loc_us-gaap_EquitySecuritiesMember_b2f3224c-7f49-4069-850a-88a6161a4e02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_USAndNonUSGovernmentObligationsMember_c554d020-02e7-49bb-bec3-5f69de9ed023" xlink:href="virt-20240930.xsd#virt_USAndNonUSGovernmentObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_16f7bfd8-f141-44fd-8575-c0b6b8d35d40" xlink:to="loc_virt_USAndNonUSGovernmentObligationsMember_c554d020-02e7-49bb-bec3-5f69de9ed023" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BondsMember_70d84f04-88e7-49eb-871d-900d31717437" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_16f7bfd8-f141-44fd-8575-c0b6b8d35d40" xlink:to="loc_us-gaap_BondsMember_70d84f04-88e7-49eb-871d-900d31717437" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ExchangeTradedNotesMember_7a5b35c0-f98c-4f2c-ad18-061e89f9c8d2" xlink:href="virt-20240930.xsd#virt_ExchangeTradedNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_16f7bfd8-f141-44fd-8575-c0b6b8d35d40" xlink:to="loc_virt_ExchangeTradedNotesMember_7a5b35c0-f98c-4f2c-ad18-061e89f9c8d2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_606c4967-5e77-4ea3-b0f5-1ef9919bbdba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_16f7bfd8-f141-44fd-8575-c0b6b8d35d40" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_606c4967-5e77-4ea3-b0f5-1ef9919bbdba" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OptionMember_5eabc8d4-0cbf-4693-9a6e-cfb45188d843" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_16f7bfd8-f141-44fd-8575-c0b6b8d35d40" xlink:to="loc_us-gaap_OptionMember_5eabc8d4-0cbf-4693-9a6e-cfb45188d843" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_FairValueOptionInvestmentMember_f790ccd6-e138-4bd8-a2d8-bf9e18030975" xlink:href="virt-20240930.xsd#virt_FairValueOptionInvestmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_16f7bfd8-f141-44fd-8575-c0b6b8d35d40" xlink:to="loc_virt_FairValueOptionInvestmentMember_f790ccd6-e138-4bd8-a2d8-bf9e18030975" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ExchangeStockMember_f9e308bc-db80-455e-a868-c2235269bc95" xlink:href="virt-20240930.xsd#virt_ExchangeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_16f7bfd8-f141-44fd-8575-c0b6b8d35d40" xlink:to="loc_virt_ExchangeStockMember_f9e308bc-db80-455e-a868-c2235269bc95" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_InterestRateSwapsAndDigitalAssetsMember_51024c31-e57e-4cb9-a90d-08a9dc4e5fe7" xlink:href="virt-20240930.xsd#virt_InterestRateSwapsAndDigitalAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_16f7bfd8-f141-44fd-8575-c0b6b8d35d40" xlink:to="loc_virt_InterestRateSwapsAndDigitalAssetsMember_51024c31-e57e-4cb9-a90d-08a9dc4e5fe7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_DigitalAssetsMember_25413abd-4448-4d58-9197-8bbc1359ef49" xlink:href="virt-20240930.xsd#virt_DigitalAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_InterestRateSwapsAndDigitalAssetsMember_51024c31-e57e-4cb9-a90d-08a9dc4e5fe7" xlink:to="loc_virt_DigitalAssetsMember_25413abd-4448-4d58-9197-8bbc1359ef49" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_PayablesLinkedToBrokerDealersAndClearingOrganizationsMember_e80e41c7-6819-46a3-9389-8b7aff735072" xlink:href="virt-20240930.xsd#virt_PayablesLinkedToBrokerDealersAndClearingOrganizationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_16f7bfd8-f141-44fd-8575-c0b6b8d35d40" xlink:to="loc_virt_PayablesLinkedToBrokerDealersAndClearingOrganizationsMember_e80e41c7-6819-46a3-9389-8b7aff735072" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusAxis_d3f17966-ed49-4707-bab6-6aaafb1cd798" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PledgedStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c9af2458-3ac0-451c-9c3e-4d4b95a96a6b" xlink:to="loc_us-gaap_PledgedStatusAxis_d3f17966-ed49-4707-bab6-6aaafb1cd798" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusDomain_d3f17966-ed49-4707-bab6-6aaafb1cd798_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PledgedStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PledgedStatusAxis_d3f17966-ed49-4707-bab6-6aaafb1cd798" xlink:to="loc_us-gaap_PledgedStatusDomain_d3f17966-ed49-4707-bab6-6aaafb1cd798_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusDomain_cecd6526-f36a-442f-b094-4ec0aad0f5b3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PledgedStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PledgedStatusAxis_d3f17966-ed49-4707-bab6-6aaafb1cd798" xlink:to="loc_us-gaap_PledgedStatusDomain_cecd6526-f36a-442f-b094-4ec0aad0f5b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetNotPledgedAsCollateralMember_9c5a5970-8011-4f0f-a261-91efa44c4e38" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetNotPledgedAsCollateralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PledgedStatusDomain_cecd6526-f36a-442f-b094-4ec0aad0f5b3" xlink:to="loc_us-gaap_AssetNotPledgedAsCollateralMember_9c5a5970-8011-4f0f-a261-91efa44c4e38" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetPledgedAsCollateralMember_eb6fc1d4-2792-4b11-9a8f-71913258a829" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetPledgedAsCollateralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PledgedStatusDomain_cecd6526-f36a-442f-b094-4ec0aad0f5b3" xlink:to="loc_us-gaap_AssetPledgedAsCollateralMember_eb6fc1d4-2792-4b11-9a8f-71913258a829" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_6e4e7485-f6a5-46fb-bfda-40c27f326df2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c9af2458-3ac0-451c-9c3e-4d4b95a96a6b" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_6e4e7485-f6a5-46fb-bfda-40c27f326df2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_6e4e7485-f6a5-46fb-bfda-40c27f326df2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_6e4e7485-f6a5-46fb-bfda-40c27f326df2" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_6e4e7485-f6a5-46fb-bfda-40c27f326df2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_e2b51211-7057-45a1-a959-3a96bcbe7683" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_6e4e7485-f6a5-46fb-bfda-40c27f326df2" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_e2b51211-7057-45a1-a959-3a96bcbe7683" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_de28eb33-06ee-4d66-afa9-f5e1c3f713f5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_e2b51211-7057-45a1-a959-3a96bcbe7683" xlink:to="loc_us-gaap_InterestRateSwapMember_de28eb33-06ee-4d66-afa9-f5e1c3f713f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_388bb0d0-8b41-4804-ac72-b78b182b3d96" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_d6e3ec67-19f5-4c9f-9eed-7ebbefc4f6ae" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_388bb0d0-8b41-4804-ac72-b78b182b3d96" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentsOwnedAtFairValue_872232d2-4f9c-46e8-a2f0-2a0a331cdaab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentsOwnedAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_388bb0d0-8b41-4804-ac72-b78b182b3d96" xlink:to="loc_us-gaap_FinancialInstrumentsOwnedAtFairValue_872232d2-4f9c-46e8-a2f0-2a0a331cdaab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_FinancialInstrumentsOwnedAndNotPledgedAtFairValueCounterPartyAndCashCollateralNetting_331b624c-3674-4343-9d48-72a6c94da7e3" xlink:href="virt-20240930.xsd#virt_FinancialInstrumentsOwnedAndNotPledgedAtFairValueCounterPartyAndCashCollateralNetting"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_388bb0d0-8b41-4804-ac72-b78b182b3d96" xlink:to="loc_virt_FinancialInstrumentsOwnedAndNotPledgedAtFairValueCounterPartyAndCashCollateralNetting_331b624c-3674-4343-9d48-72a6c94da7e3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsFairValueDisclosure_47f4f29c-b852-48bf-90fe-40834b54aff1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherAssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_388bb0d0-8b41-4804-ac72-b78b182b3d96" xlink:to="loc_us-gaap_OtherAssetsFairValueDisclosure_47f4f29c-b852-48bf-90fe-40834b54aff1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations_1b19cf75-24e1-4f00-942a-d9f0ae9927ae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_388bb0d0-8b41-4804-ac72-b78b182b3d96" xlink:to="loc_us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations_1b19cf75-24e1-4f00-942a-d9f0ae9927ae" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_6fd6d0de-a1ea-427a-9574-56d243fa650c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_d6e3ec67-19f5-4c9f-9eed-7ebbefc4f6ae" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_6fd6d0de-a1ea-427a-9574-56d243fa650c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentsSoldNotYetPurchasedAtFairValue_a47ffe34-1d1d-4963-94bf-754fdce25751" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentsSoldNotYetPurchasedAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_6fd6d0de-a1ea-427a-9574-56d243fa650c" xlink:to="loc_us-gaap_FinancialInstrumentsSoldNotYetPurchasedAtFairValue_a47ffe34-1d1d-4963-94bf-754fdce25751" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_FinancialInstrumentsSoldNotYetPurchasedAtFairValueCounterPartyAndCashCollateralNetting_b5c04e36-a753-4d30-a661-cc54703f4338" xlink:href="virt-20240930.xsd#virt_FinancialInstrumentsSoldNotYetPurchasedAtFairValueCounterPartyAndCashCollateralNetting"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_6fd6d0de-a1ea-427a-9574-56d243fa650c" xlink:to="loc_virt_FinancialInstrumentsSoldNotYetPurchasedAtFairValueCounterPartyAndCashCollateralNetting_b5c04e36-a753-4d30-a661-cc54703f4338" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_PayablesToBrokerDealersAndClearingOrganizations_b4fc27b7-413c-49de-a1c2-ac685efc34ee" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_PayablesToBrokerDealersAndClearingOrganizations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_6fd6d0de-a1ea-427a-9574-56d243fa650c" xlink:to="loc_srt_PayablesToBrokerDealersAndClearingOrganizations_b4fc27b7-413c-49de-a1c2-ac685efc34ee" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/FinancialAssetsandLiabilitiesFairValueInputsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#FinancialAssetsandLiabilitiesFairValueInputsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/FinancialAssetsandLiabilitiesFairValueInputsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_5a6d018a-3ea9-493a-99e2-16821b926d6e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_ce8a4bba-318c-4498-818f-b3d4244b3686" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_5a6d018a-3ea9-493a-99e2-16821b926d6e" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_ce8a4bba-318c-4498-818f-b3d4244b3686" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_e57a46c5-427d-400a-a69b-42614901bb27" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_ce8a4bba-318c-4498-818f-b3d4244b3686" xlink:to="loc_srt_RangeAxis_e57a46c5-427d-400a-a69b-42614901bb27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_e57a46c5-427d-400a-a69b-42614901bb27_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_e57a46c5-427d-400a-a69b-42614901bb27" xlink:to="loc_srt_RangeMember_e57a46c5-427d-400a-a69b-42614901bb27_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_1b40bdd4-322b-4923-be83-305cc9da6a6a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_e57a46c5-427d-400a-a69b-42614901bb27" xlink:to="loc_srt_RangeMember_1b40bdd4-322b-4923-be83-305cc9da6a6a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_45da7cde-c132-47b6-9c4e-22b4bd2718ab" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_1b40bdd4-322b-4923-be83-305cc9da6a6a" xlink:to="loc_srt_MinimumMember_45da7cde-c132-47b6-9c4e-22b4bd2718ab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_ed3ac282-49fd-4a4d-bcfc-ba3ad48a49ae" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_1b40bdd4-322b-4923-be83-305cc9da6a6a" xlink:to="loc_srt_MaximumMember_ed3ac282-49fd-4a4d-bcfc-ba3ad48a49ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_WeightedAverageMember_3b53ad0c-3115-4c44-95d3-0ff5069d5eee" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_WeightedAverageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_1b40bdd4-322b-4923-be83-305cc9da6a6a" xlink:to="loc_srt_WeightedAverageMember_3b53ad0c-3115-4c44-95d3-0ff5069d5eee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueAxis_4eb79f34-fab6-48ac-8802-88fbd79085af" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationTechniqueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_ce8a4bba-318c-4498-818f-b3d4244b3686" xlink:to="loc_us-gaap_ValuationTechniqueAxis_4eb79f34-fab6-48ac-8802-88fbd79085af" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_4eb79f34-fab6-48ac-8802-88fbd79085af_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationTechniqueAxis_4eb79f34-fab6-48ac-8802-88fbd79085af" xlink:to="loc_us-gaap_ValuationTechniqueDomain_4eb79f34-fab6-48ac-8802-88fbd79085af_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_3ca14050-bb0d-4a17-83d1-55299c87950f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationTechniqueAxis_4eb79f34-fab6-48ac-8802-88fbd79085af" xlink:to="loc_us-gaap_ValuationTechniqueDomain_3ca14050-bb0d-4a17-83d1-55299c87950f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDiscountedCashFlowMember_0cea3895-2684-45a9-b486-1f7255190e04" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationTechniqueDiscountedCashFlowMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_3ca14050-bb0d-4a17-83d1-55299c87950f" xlink:to="loc_us-gaap_ValuationTechniqueDiscountedCashFlowMember_0cea3895-2684-45a9-b486-1f7255190e04" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketApproachValuationTechniqueMember_eb6626d2-45f5-4192-bb64-439e13559150" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MarketApproachValuationTechniqueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_3ca14050-bb0d-4a17-83d1-55299c87950f" xlink:to="loc_us-gaap_MarketApproachValuationTechniqueMember_eb6626d2-45f5-4192-bb64-439e13559150" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_c742f1f5-7fc0-454b-b90d-9614b02cfe67" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_ce8a4bba-318c-4498-818f-b3d4244b3686" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_c742f1f5-7fc0-454b-b90d-9614b02cfe67" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_c742f1f5-7fc0-454b-b90d-9614b02cfe67_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_c742f1f5-7fc0-454b-b90d-9614b02cfe67" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_c742f1f5-7fc0-454b-b90d-9614b02cfe67_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_706bafff-511b-465c-8716-b96c0d939fbd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_c742f1f5-7fc0-454b-b90d-9614b02cfe67" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_706bafff-511b-465c-8716-b96c0d939fbd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputLongTermRevenueGrowthRateMember_d3fc755b-3268-4360-b95f-93b5d6a6c014" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputLongTermRevenueGrowthRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_706bafff-511b-465c-8716-b96c0d939fbd" xlink:to="loc_us-gaap_MeasurementInputLongTermRevenueGrowthRateMember_d3fc755b-3268-4360-b95f-93b5d6a6c014" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_e1262a1e-d4ba-4528-8cfd-a0639552da28" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_706bafff-511b-465c-8716-b96c0d939fbd" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_e1262a1e-d4ba-4528-8cfd-a0639552da28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputEbitdaMultipleMember_278656a8-fe59-401a-ba1f-55bf86d7d40d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputEbitdaMultipleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_706bafff-511b-465c-8716-b96c0d939fbd" xlink:to="loc_us-gaap_MeasurementInputEbitdaMultipleMember_278656a8-fe59-401a-ba1f-55bf86d7d40d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNi_44885a8b-0b88-4c06-9e42-8040a91ba075" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquitySecuritiesFvNi"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_5a6d018a-3ea9-493a-99e2-16821b926d6e" xlink:to="loc_us-gaap_EquitySecuritiesFvNi_44885a8b-0b88-4c06-9e42-8040a91ba075" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiMeasurementInput_69b56eb1-c39b-45b5-9dec-bea0a6318ec0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquitySecuritiesFvNiMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_5a6d018a-3ea9-493a-99e2-16821b926d6e" xlink:to="loc_us-gaap_EquitySecuritiesFvNiMeasurementInput_69b56eb1-c39b-45b5-9dec-bea0a6318ec0" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/FinancialAssetsandLiabilitiesLevel3financialinstrumentsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#FinancialAssetsandLiabilitiesLevel3financialinstrumentsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/FinancialAssetsandLiabilitiesLevel3financialinstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_95650857-adb6-4e11-b212-6756db5e9187" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c09793f7-19b7-4cb6-8389-cfcb2ac9b232" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_95650857-adb6-4e11-b212-6756db5e9187" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c09793f7-19b7-4cb6-8389-cfcb2ac9b232" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_4c1fa15f-30e1-45a5-971c-f95633671027" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c09793f7-19b7-4cb6-8389-cfcb2ac9b232" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_4c1fa15f-30e1-45a5-971c-f95633671027" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_4c1fa15f-30e1-45a5-971c-f95633671027_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_4c1fa15f-30e1-45a5-971c-f95633671027" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_4c1fa15f-30e1-45a5-971c-f95633671027_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_dd590751-a980-49f7-868a-19ce9a134260" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_4c1fa15f-30e1-45a5-971c-f95633671027" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_dd590751-a980-49f7-868a-19ce9a134260" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_FairValueOptionInvestmentMember_f1865dc6-68ef-437b-8b83-63e21ca5743d" xlink:href="virt-20240930.xsd#virt_FairValueOptionInvestmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_dd590751-a980-49f7-868a-19ce9a134260" xlink:to="loc_virt_FairValueOptionInvestmentMember_f1865dc6-68ef-437b-8b83-63e21ca5743d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_OtherInvestmentMember_d1da29e1-d26a-4bae-8ddb-e9dd1010b381" xlink:href="virt-20240930.xsd#virt_OtherInvestmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_dd590751-a980-49f7-868a-19ce9a134260" xlink:to="loc_virt_OtherInvestmentMember_d1da29e1-d26a-4bae-8ddb-e9dd1010b381" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueRecurringBasisUnobservableInputReconciliationAssetGainLossStatementOfIncomeExtensibleList_be3fe8e9-bae5-4aa3-a7e3-db08b6a2887e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueRecurringBasisUnobservableInputReconciliationAssetGainLossStatementOfIncomeExtensibleList"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_95650857-adb6-4e11-b212-6756db5e9187" xlink:to="loc_us-gaap_FairValueRecurringBasisUnobservableInputReconciliationAssetGainLossStatementOfIncomeExtensibleList_be3fe8e9-bae5-4aa3-a7e3-db08b6a2887e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetRecurringBasisStillHeldUnrealizedGainLossStatementOfIncomeExtensibleList_e3fd14ef-1ca9-4bf2-9fb9-9c1ee387c423" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetRecurringBasisStillHeldUnrealizedGainLossStatementOfIncomeExtensibleList"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_95650857-adb6-4e11-b212-6756db5e9187" xlink:to="loc_us-gaap_FairValueAssetRecurringBasisStillHeldUnrealizedGainLossStatementOfIncomeExtensibleList_e3fd14ef-1ca9-4bf2-9fb9-9c1ee387c423" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_466e47e9-3608-4c74-8f90-6f4092bea5b8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_95650857-adb6-4e11-b212-6756db5e9187" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_466e47e9-3608-4c74-8f90-6f4092bea5b8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_bbb66241-025a-4773-8f7d-b4072511daa5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_466e47e9-3608-4c74-8f90-6f4092bea5b8" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_bbb66241-025a-4773-8f7d-b4072511daa5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases_a48d46b8-5c70-4d75-a4ea-e5fc1e70aaf1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_466e47e9-3608-4c74-8f90-6f4092bea5b8" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases_a48d46b8-5c70-4d75-a4ea-e5fc1e70aaf1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_42afbc4f-93ec-4d45-b636-df1ddc55c6d4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_466e47e9-3608-4c74-8f90-6f4092bea5b8" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_42afbc4f-93ec-4d45-b636-df1ddc55c6d4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet_ef0d3624-7ac5-41b0-9341-ebac6c4bcc3a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_466e47e9-3608-4c74-8f90-6f4092bea5b8" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet_ef0d3624-7ac5-41b0-9341-ebac6c4bcc3a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_112727c5-6a4e-48db-8fbb-6ab12729f2ac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_466e47e9-3608-4c74-8f90-6f4092bea5b8" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_112727c5-6a4e-48db-8fbb-6ab12729f2ac" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_7bd13194-7fa9-404f-a11c-dc39537972af" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss_e6cf505c-006a-4d72-88f4-cccb40eb6ef6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_95650857-adb6-4e11-b212-6756db5e9187" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss_e6cf505c-006a-4d72-88f4-cccb40eb6ef6" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/FinancialAssetsandLiabilitiesNotMeasuredatFairValueonRecurringBasisDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#FinancialAssetsandLiabilitiesNotMeasuredatFairValueonRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/FinancialAssetsandLiabilitiesNotMeasuredatFairValueonRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_9ae71776-9851-4e91-8e23-cafc5f9e2219" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_a143cef2-50cc-4e11-a4f2-157602c47cd2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByBalanceSheetGroupingTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_9ae71776-9851-4e91-8e23-cafc5f9e2219" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_a143cef2-50cc-4e11-a4f2-157602c47cd2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_caa08604-36e3-414c-9db2-896e7c110dfc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_a143cef2-50cc-4e11-a4f2-157602c47cd2" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_caa08604-36e3-414c-9db2-896e7c110dfc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_caa08604-36e3-414c-9db2-896e7c110dfc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_caa08604-36e3-414c-9db2-896e7c110dfc" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_caa08604-36e3-414c-9db2-896e7c110dfc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_4e85d054-4758-4aee-a0fc-cef880cf38b8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_caa08604-36e3-414c-9db2-896e7c110dfc" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_4e85d054-4758-4aee-a0fc-cef880cf38b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_8cb9e8da-50a7-49b5-a3d7-2327b1b051c5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_4e85d054-4758-4aee-a0fc-cef880cf38b8" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_8cb9e8da-50a7-49b5-a3d7-2327b1b051c5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_5294b858-c8d3-40e4-a7b2-6caefe0a790e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_8cb9e8da-50a7-49b5-a3d7-2327b1b051c5" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_5294b858-c8d3-40e4-a7b2-6caefe0a790e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_95ada599-73f1-4ae7-acbf-aecdb5d532d1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_8cb9e8da-50a7-49b5-a3d7-2327b1b051c5" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_95ada599-73f1-4ae7-acbf-aecdb5d532d1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_a43df1f1-a7de-4940-b045-7adab879935b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_a143cef2-50cc-4e11-a4f2-157602c47cd2" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_a43df1f1-a7de-4940-b045-7adab879935b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_a43df1f1-a7de-4940-b045-7adab879935b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_a43df1f1-a7de-4940-b045-7adab879935b" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_a43df1f1-a7de-4940-b045-7adab879935b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_534492cc-623a-4335-8fa2-8d99c3be1c9a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_a43df1f1-a7de-4940-b045-7adab879935b" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_534492cc-623a-4335-8fa2-8d99c3be1c9a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_fb6be090-1f02-49d7-990e-94d763bfbf00" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_534492cc-623a-4335-8fa2-8d99c3be1c9a" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_fb6be090-1f02-49d7-990e-94d763bfbf00" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_350940bf-1230-468e-9e35-9a6ef9053aea" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_534492cc-623a-4335-8fa2-8d99c3be1c9a" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_350940bf-1230-468e-9e35-9a6ef9053aea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_710c6beb-3b28-4d23-b705-ab72edf02372" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_534492cc-623a-4335-8fa2-8d99c3be1c9a" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_710c6beb-3b28-4d23-b705-ab72edf02372" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_15cdeded-fa80-4b76-a4f5-f104dd84faf5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_9ae71776-9851-4e91-8e23-cafc5f9e2219" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_15cdeded-fa80-4b76-a4f5-f104dd84faf5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_47321c62-5739-403e-a6d5-026bf35b712e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_15cdeded-fa80-4b76-a4f5-f104dd84faf5" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_47321c62-5739-403e-a6d5-026bf35b712e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCash_fc15e6e2-795a-4041-a34b-ed70c38ee578" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_15cdeded-fa80-4b76-a4f5-f104dd84faf5" xlink:to="loc_us-gaap_RestrictedCash_fc15e6e2-795a-4041-a34b-ed70c38ee578" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesBorrowedFairValueDisclosure_d3ad7ba3-da9a-4ab8-b7bb-5372449a68c4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesBorrowedFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_15cdeded-fa80-4b76-a4f5-f104dd84faf5" xlink:to="loc_us-gaap_SecuritiesBorrowedFairValueDisclosure_d3ad7ba3-da9a-4ab8-b7bb-5372449a68c4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalFundsSoldAndSecuritiesBorrowedOrPurchasedUnderAgreementsToResellFairValueDisclosure_25bada96-458c-41e7-bbcc-a6dc92229416" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FederalFundsSoldAndSecuritiesBorrowedOrPurchasedUnderAgreementsToResellFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_15cdeded-fa80-4b76-a4f5-f104dd84faf5" xlink:to="loc_us-gaap_FederalFundsSoldAndSecuritiesBorrowedOrPurchasedUnderAgreementsToResellFairValueDisclosure_25bada96-458c-41e7-bbcc-a6dc92229416" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations_004b23fd-6efb-47a1-b38d-6e2d1c36e513" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_15cdeded-fa80-4b76-a4f5-f104dd84faf5" xlink:to="loc_us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations_004b23fd-6efb-47a1-b38d-6e2d1c36e513" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesFromCustomers_148db116-8426-4a9c-9a11-92be2379955e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReceivablesFromCustomers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_15cdeded-fa80-4b76-a4f5-f104dd84faf5" xlink:to="loc_us-gaap_ReceivablesFromCustomers_148db116-8426-4a9c-9a11-92be2379955e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssets_88c12050-6578-44f4-aa71-53f355e8b656" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_15cdeded-fa80-4b76-a4f5-f104dd84faf5" xlink:to="loc_us-gaap_OtherAssets_88c12050-6578-44f4-aa71-53f355e8b656" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_871504ff-4bfc-41dd-969e-c8717c53d7ad" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_15cdeded-fa80-4b76-a4f5-f104dd84faf5" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_871504ff-4bfc-41dd-969e-c8717c53d7ad" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_74c43537-c83b-4ba1-9d51-d3fccae1ebe7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_9ae71776-9851-4e91-8e23-cafc5f9e2219" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_74c43537-c83b-4ba1-9d51-d3fccae1ebe7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShorttermDebtFairValue_610d124b-c316-48da-9507-22a3a7bdb4d7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShorttermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_74c43537-c83b-4ba1-9d51-d3fccae1ebe7" xlink:to="loc_us-gaap_ShorttermDebtFairValue_610d124b-c316-48da-9507-22a3a7bdb4d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_6436c72a-af9b-4b73-ad18-91f35edc4b15" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_74c43537-c83b-4ba1-9d51-d3fccae1ebe7" xlink:to="loc_us-gaap_LongTermDebtFairValue_6436c72a-af9b-4b73-ad18-91f35edc4b15" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SecuritiesLoanedFairValueDisclosure_f0c99a25-61e3-4a70-9468-a69cf755b437" xlink:href="virt-20240930.xsd#virt_SecuritiesLoanedFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_74c43537-c83b-4ba1-9d51-d3fccae1ebe7" xlink:to="loc_virt_SecuritiesLoanedFairValueDisclosure_f0c99a25-61e3-4a70-9468-a69cf755b437" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SecuritiesSoldUnderAgreementsToRepurchaseFairValueDisclosure_cdf3bd76-74f0-4f48-a2db-80bf8e6b3a00" xlink:href="virt-20240930.xsd#virt_SecuritiesSoldUnderAgreementsToRepurchaseFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_74c43537-c83b-4ba1-9d51-d3fccae1ebe7" xlink:to="loc_virt_SecuritiesSoldUnderAgreementsToRepurchaseFairValueDisclosure_cdf3bd76-74f0-4f48-a2db-80bf8e6b3a00" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_PayablesToBrokerDealersAndClearingOrganizations_663f5e1c-9b59-481d-b017-56b3aedad3f2" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_PayablesToBrokerDealersAndClearingOrganizations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_74c43537-c83b-4ba1-9d51-d3fccae1ebe7" xlink:to="loc_srt_PayablesToBrokerDealersAndClearingOrganizations_663f5e1c-9b59-481d-b017-56b3aedad3f2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_PayablesToCustomers_2f129040-628c-456b-b68e-313f7391b53e" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_PayablesToCustomers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_74c43537-c83b-4ba1-9d51-d3fccae1ebe7" xlink:to="loc_srt_PayablesToCustomers_2f129040-628c-456b-b68e-313f7391b53e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilities_38dee1ee-e5d9-4119-9d0c-13ce009f9985" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_74c43537-c83b-4ba1-9d51-d3fccae1ebe7" xlink:to="loc_us-gaap_OtherLiabilities_38dee1ee-e5d9-4119-9d0c-13ce009f9985" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_af7107e1-36d1-440d-a81d-9fe85790ed09" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_74c43537-c83b-4ba1-9d51-d3fccae1ebe7" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_af7107e1-36d1-440d-a81d-9fe85790ed09" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/FinancialAssetsandLiabilitiesNettingofCertainFinancialAssetsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#FinancialAssetsandLiabilitiesNettingofCertainFinancialAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/FinancialAssetsandLiabilitiesNettingofCertainFinancialAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingAssetsLineItems_924fb815-a2f1-4e5d-8a2d-43ab9ac65ca8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OffsettingAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingAssetsTable_c6d23e9f-cedd-446b-9d16-e77b1bca17c2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OffsettingAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OffsettingAssetsLineItems_924fb815-a2f1-4e5d-8a2d-43ab9ac65ca8" xlink:to="loc_us-gaap_OffsettingAssetsTable_c6d23e9f-cedd-446b-9d16-e77b1bca17c2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_ded382fd-d7c9-455f-9717-c1cf7a37a588" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OffsettingAssetsTable_c6d23e9f-cedd-446b-9d16-e77b1bca17c2" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_ded382fd-d7c9-455f-9717-c1cf7a37a588" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_ded382fd-d7c9-455f-9717-c1cf7a37a588_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_ded382fd-d7c9-455f-9717-c1cf7a37a588" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_ded382fd-d7c9-455f-9717-c1cf7a37a588_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_e2e4b0a0-e090-4db5-952c-ca39f69424fc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_ded382fd-d7c9-455f-9717-c1cf7a37a588" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_e2e4b0a0-e090-4db5-952c-ca39f69424fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_2acd32d2-2805-4176-9a71-3d19c387db12" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_e2e4b0a0-e090-4db5-952c-ca39f69424fc" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_2acd32d2-2805-4176-9a71-3d19c387db12" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OptionMember_2e623dc5-04ea-4000-8fb5-9e2c1b6a5b16" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_e2e4b0a0-e090-4db5-952c-ca39f69424fc" xlink:to="loc_us-gaap_OptionMember_2e623dc5-04ea-4000-8fb5-9e2c1b6a5b16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingSecuritiesBorrowedAbstract_a0f98101-a18f-4956-b805-7a9d5e442b36" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OffsettingSecuritiesBorrowedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingAssetsLineItems_924fb815-a2f1-4e5d-8a2d-43ab9ac65ca8" xlink:to="loc_us-gaap_OffsettingSecuritiesBorrowedAbstract_a0f98101-a18f-4956-b805-7a9d5e442b36" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesBorrowedGross_0b627c86-5340-4a9d-aaaf-756735122830" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesBorrowedGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingSecuritiesBorrowedAbstract_a0f98101-a18f-4956-b805-7a9d5e442b36" xlink:to="loc_us-gaap_SecuritiesBorrowedGross_0b627c86-5340-4a9d-aaaf-756735122830" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesBorrowedLiability_312f5ddb-9dde-4b79-a268-dbc7b19d5266" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesBorrowedLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingSecuritiesBorrowedAbstract_a0f98101-a18f-4956-b805-7a9d5e442b36" xlink:to="loc_us-gaap_SecuritiesBorrowedLiability_312f5ddb-9dde-4b79-a268-dbc7b19d5266" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecurityBorrowedAfterOffsetSubjectToMasterNettingArrangement_7b528422-5616-4390-8240-f028b0e0e5e3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecurityBorrowedAfterOffsetSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingSecuritiesBorrowedAbstract_a0f98101-a18f-4956-b805-7a9d5e442b36" xlink:to="loc_us-gaap_SecurityBorrowedAfterOffsetSubjectToMasterNettingArrangement_7b528422-5616-4390-8240-f028b0e0e5e3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SecuritiesBorrowedGrossAmountsNotOffsetAbstract_c7b96a62-59a3-42e2-bb5b-da1a04a5b831" xlink:href="virt-20240930.xsd#virt_SecuritiesBorrowedGrossAmountsNotOffsetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingSecuritiesBorrowedAbstract_a0f98101-a18f-4956-b805-7a9d5e442b36" xlink:to="loc_virt_SecuritiesBorrowedGrossAmountsNotOffsetAbstract_c7b96a62-59a3-42e2-bb5b-da1a04a5b831" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesBorrowedCollateralObligationToReturnSecurities_22566cc5-5b57-4ca6-af80-dfd240024cc1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesBorrowedCollateralObligationToReturnSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_SecuritiesBorrowedGrossAmountsNotOffsetAbstract_c7b96a62-59a3-42e2-bb5b-da1a04a5b831" xlink:to="loc_us-gaap_SecuritiesBorrowedCollateralObligationToReturnSecurities_22566cc5-5b57-4ca6-af80-dfd240024cc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesBorrowedCollateralObligationToReturnCash_e610016c-bac6-4883-97cc-0275aa1019f5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesBorrowedCollateralObligationToReturnCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_SecuritiesBorrowedGrossAmountsNotOffsetAbstract_c7b96a62-59a3-42e2-bb5b-da1a04a5b831" xlink:to="loc_us-gaap_SecuritiesBorrowedCollateralObligationToReturnCash_e610016c-bac6-4883-97cc-0275aa1019f5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesBorrowedOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection_05ac1fb5-baab-4234-990b-b0560b143789" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesBorrowedOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingSecuritiesBorrowedAbstract_a0f98101-a18f-4956-b805-7a9d5e442b36" xlink:to="loc_us-gaap_SecuritiesBorrowedOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection_05ac1fb5-baab-4234-990b-b0560b143789" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellAbstract_6b44afb2-e867-425b-bb9a-220c8d1126d0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesPurchasedUnderAgreementsToResellAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingAssetsLineItems_924fb815-a2f1-4e5d-8a2d-43ab9ac65ca8" xlink:to="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellAbstract_6b44afb2-e867-425b-bb9a-220c8d1126d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellGross_a835cd72-bcaf-45e0-9afc-10f9ec35bea3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesPurchasedUnderAgreementsToResellGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellAbstract_6b44afb2-e867-425b-bb9a-220c8d1126d0" xlink:to="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellGross_a835cd72-bcaf-45e0-9afc-10f9ec35bea3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellLiability_333b5a77-deaa-4ae1-9fde-73b110d30a10" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesPurchasedUnderAgreementsToResellLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellAbstract_6b44afb2-e867-425b-bb9a-220c8d1126d0" xlink:to="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellLiability_333b5a77-deaa-4ae1-9fde-73b110d30a10" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecurityPurchasedUnderAgreementToResellAfterOffsetSubjectToMasterNettingArrangement_b86e961c-8974-4b34-976d-572667a4e8da" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecurityPurchasedUnderAgreementToResellAfterOffsetSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellAbstract_6b44afb2-e867-425b-bb9a-220c8d1126d0" xlink:to="loc_us-gaap_SecurityPurchasedUnderAgreementToResellAfterOffsetSubjectToMasterNettingArrangement_b86e961c-8974-4b34-976d-572667a4e8da" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellAmountOffsetAgainstCollateralAbstract_f7c888c7-1292-4c94-a1c3-d663b41cb0dc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesPurchasedUnderAgreementsToResellAmountOffsetAgainstCollateralAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellAbstract_6b44afb2-e867-425b-bb9a-220c8d1126d0" xlink:to="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellAmountOffsetAgainstCollateralAbstract_f7c888c7-1292-4c94-a1c3-d663b41cb0dc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellCollateralObligationToReturnSecurities_3d5f7b87-3321-47c9-9fa2-2e25ea15ed22" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesPurchasedUnderAgreementsToResellCollateralObligationToReturnSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellAmountOffsetAgainstCollateralAbstract_f7c888c7-1292-4c94-a1c3-d663b41cb0dc" xlink:to="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellCollateralObligationToReturnSecurities_3d5f7b87-3321-47c9-9fa2-2e25ea15ed22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellCollateralObligationToReturnCash_180f528e-d116-49a3-a906-7c50ea1a386e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesPurchasedUnderAgreementsToResellCollateralObligationToReturnCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellAmountOffsetAgainstCollateralAbstract_f7c888c7-1292-4c94-a1c3-d663b41cb0dc" xlink:to="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellCollateralObligationToReturnCash_180f528e-d116-49a3-a906-7c50ea1a386e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection_41a00601-8797-42bb-afec-2da5bd391662" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesPurchasedUnderAgreementsToResellOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellAbstract_6b44afb2-e867-425b-bb9a-220c8d1126d0" xlink:to="loc_us-gaap_SecuritiesPurchasedUnderAgreementsToResellOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection_41a00601-8797-42bb-afec-2da5bd391662" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_OffsettingTradingAssetsAtFairValueAbstract_19c65dd1-3b66-4fb4-85cf-1a79d2c5d7e8" xlink:href="virt-20240930.xsd#virt_OffsettingTradingAssetsAtFairValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingAssetsLineItems_924fb815-a2f1-4e5d-8a2d-43ab9ac65ca8" xlink:to="loc_virt_OffsettingTradingAssetsAtFairValueAbstract_19c65dd1-3b66-4fb4-85cf-1a79d2c5d7e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_6b1d59b0-3b9e-4232-a9f5-82f6ac181519" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OffsettingTradingAssetsAtFairValueAbstract_19c65dd1-3b66-4fb4-85cf-1a79d2c5d7e8" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_6b1d59b0-3b9e-4232-a9f5-82f6ac181519" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiability_aaa1adc7-e8da-48e2-bcbf-782608f21ff9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssetFairValueGrossLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OffsettingTradingAssetsAtFairValueAbstract_19c65dd1-3b66-4fb4-85cf-1a79d2c5d7e8" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiability_aaa1adc7-e8da-48e2-bcbf-782608f21ff9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_5ddbe88f-629c-40d5-96ff-ba98f123fbc1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OffsettingTradingAssetsAtFairValueAbstract_19c65dd1-3b66-4fb4-85cf-1a79d2c5d7e8" xlink:to="loc_us-gaap_DerivativeAssets_5ddbe88f-629c-40d5-96ff-ba98f123fbc1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SecuritiesLoanedGrossAmountsNotOffsetAbstract_5e99f716-d1af-4a6f-9875-825bc8ca15de" xlink:href="virt-20240930.xsd#virt_SecuritiesLoanedGrossAmountsNotOffsetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OffsettingTradingAssetsAtFairValueAbstract_19c65dd1-3b66-4fb4-85cf-1a79d2c5d7e8" xlink:to="loc_virt_SecuritiesLoanedGrossAmountsNotOffsetAbstract_5e99f716-d1af-4a6f-9875-825bc8ca15de" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCollateralObligationToReturnSecurities_f504cbca-18c0-4354-b9f9-308a2a07aa3f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeCollateralObligationToReturnSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_SecuritiesLoanedGrossAmountsNotOffsetAbstract_5e99f716-d1af-4a6f-9875-825bc8ca15de" xlink:to="loc_us-gaap_DerivativeCollateralObligationToReturnSecurities_f504cbca-18c0-4354-b9f9-308a2a07aa3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCollateralObligationToReturnCash_515a7bce-3152-4598-948f-fa39c4b5f21e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeCollateralObligationToReturnCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_SecuritiesLoanedGrossAmountsNotOffsetAbstract_5e99f716-d1af-4a6f-9875-825bc8ca15de" xlink:to="loc_us-gaap_DerivativeCollateralObligationToReturnCash_515a7bce-3152-4598-948f-fa39c4b5f21e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueAfterOffsetAndDeductionSubjectToMasterNettingArrangement_65e79989-4473-4b24-8362-36c7af08ed51" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssetFairValueAfterOffsetAndDeductionSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_SecuritiesLoanedGrossAmountsNotOffsetAbstract_5e99f716-d1af-4a6f-9875-825bc8ca15de" xlink:to="loc_us-gaap_DerivativeAssetFairValueAfterOffsetAndDeductionSubjectToMasterNettingArrangement_65e79989-4473-4b24-8362-36c7af08ed51" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingDerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedAbstract_329a22cf-b9ae-4fc3-b5e1-89113463f1ba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OffsettingDerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingAssetsLineItems_924fb815-a2f1-4e5d-8a2d-43ab9ac65ca8" xlink:to="loc_us-gaap_OffsettingDerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedAbstract_329a22cf-b9ae-4fc3-b5e1-89113463f1ba" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedGross_5ac760ac-cba8-4deb-b9d2-6930a00e5d2a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedAbstract_329a22cf-b9ae-4fc3-b5e1-89113463f1ba" xlink:to="loc_us-gaap_DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedGross_5ac760ac-cba8-4deb-b9d2-6930a00e5d2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedLiability_08433384-5b25-4f73-a313-706da1e1e8bc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedAbstract_329a22cf-b9ae-4fc3-b5e1-89113463f1ba" xlink:to="loc_us-gaap_DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedLiability_08433384-5b25-4f73-a313-706da1e1e8bc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetSecurityPurchasedUnderAgreementToResellSecurityBorrowedAfterOffsetSubjectToMasterNettingArrangement_c6a088e6-8250-43c6-9584-b40dc170f3c1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssetSecurityPurchasedUnderAgreementToResellSecurityBorrowedAfterOffsetSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedAbstract_329a22cf-b9ae-4fc3-b5e1-89113463f1ba" xlink:to="loc_us-gaap_DerivativeAssetSecurityPurchasedUnderAgreementToResellSecurityBorrowedAfterOffsetSubjectToMasterNettingArrangement_c6a088e6-8250-43c6-9584-b40dc170f3c1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_DerivativeFairValueOfDerivativeAssetGrossAmountsNotOffsetAbstract_a2b54b46-7b37-4394-9e3f-b836749b4d16" xlink:href="virt-20240930.xsd#virt_DerivativeFairValueOfDerivativeAssetGrossAmountsNotOffsetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedAbstract_329a22cf-b9ae-4fc3-b5e1-89113463f1ba" xlink:to="loc_virt_DerivativeFairValueOfDerivativeAssetGrossAmountsNotOffsetAbstract_a2b54b46-7b37-4394-9e3f-b836749b4d16" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedCollateralObligationToReturnSecurities_8c0a78e1-2f05-48c9-9664-b6526e3ce1b7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedCollateralObligationToReturnSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_DerivativeFairValueOfDerivativeAssetGrossAmountsNotOffsetAbstract_a2b54b46-7b37-4394-9e3f-b836749b4d16" xlink:to="loc_us-gaap_DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedCollateralObligationToReturnSecurities_8c0a78e1-2f05-48c9-9664-b6526e3ce1b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedCollateralObligationToReturnCash_db4bbf9a-df61-494c-adb7-0678d587b784" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedCollateralObligationToReturnCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_DerivativeFairValueOfDerivativeAssetGrossAmountsNotOffsetAbstract_a2b54b46-7b37-4394-9e3f-b836749b4d16" xlink:to="loc_us-gaap_DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedCollateralObligationToReturnCash_db4bbf9a-df61-494c-adb7-0678d587b784" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection_fa9a4541-203d-4415-879b-a26ade68c3d0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedAbstract_329a22cf-b9ae-4fc3-b5e1-89113463f1ba" xlink:to="loc_us-gaap_DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection_fa9a4541-203d-4415-879b-a26ade68c3d0" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/FinancialAssetsandLiabilitiesNettingofCertainFinancialLiabilitiesDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#FinancialAssetsandLiabilitiesNettingofCertainFinancialLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/FinancialAssetsandLiabilitiesNettingofCertainFinancialLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingLiabilitiesLineItems_8d6e08ee-2c02-4311-9d95-9343de741904" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OffsettingLiabilitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingLiabilitiesTable_d97037f2-8e50-435e-83ab-357d57d038fa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OffsettingLiabilitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OffsettingLiabilitiesLineItems_8d6e08ee-2c02-4311-9d95-9343de741904" xlink:to="loc_us-gaap_OffsettingLiabilitiesTable_d97037f2-8e50-435e-83ab-357d57d038fa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_ae74ff26-abca-4baa-a973-6ebed557931c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OffsettingLiabilitiesTable_d97037f2-8e50-435e-83ab-357d57d038fa" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_ae74ff26-abca-4baa-a973-6ebed557931c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_ae74ff26-abca-4baa-a973-6ebed557931c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_ae74ff26-abca-4baa-a973-6ebed557931c" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_ae74ff26-abca-4baa-a973-6ebed557931c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_29714b0a-e686-4c93-bd6f-3dd9d7050c12" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_ae74ff26-abca-4baa-a973-6ebed557931c" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_29714b0a-e686-4c93-bd6f-3dd9d7050c12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_c7e8c6f6-45db-4819-a0fb-07c4fbf07475" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_29714b0a-e686-4c93-bd6f-3dd9d7050c12" xlink:to="loc_us-gaap_InterestRateSwapMember_c7e8c6f6-45db-4819-a0fb-07c4fbf07475" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_85cf01a0-7175-45f7-8b73-6f1faccd1bb9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_29714b0a-e686-4c93-bd6f-3dd9d7050c12" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_85cf01a0-7175-45f7-8b73-6f1faccd1bb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OptionMember_96f3c984-e12b-4b84-98c3-848c44240169" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_29714b0a-e686-4c93-bd6f-3dd9d7050c12" xlink:to="loc_us-gaap_OptionMember_96f3c984-e12b-4b84-98c3-848c44240169" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingSecuritiesLoanedAbstract_54d2d08b-120c-434b-87a1-7d61ee74e9d5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OffsettingSecuritiesLoanedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingLiabilitiesLineItems_8d6e08ee-2c02-4311-9d95-9343de741904" xlink:to="loc_us-gaap_OffsettingSecuritiesLoanedAbstract_54d2d08b-120c-434b-87a1-7d61ee74e9d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesLoanedGross_7871128d-fc7e-4c35-a4b1-2d6418af44cc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesLoanedGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingSecuritiesLoanedAbstract_54d2d08b-120c-434b-87a1-7d61ee74e9d5" xlink:to="loc_us-gaap_SecuritiesLoanedGross_7871128d-fc7e-4c35-a4b1-2d6418af44cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesLoanedAsset_85cb1d94-eb02-4bf5-bbbd-e738660c8fc8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesLoanedAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingSecuritiesLoanedAbstract_54d2d08b-120c-434b-87a1-7d61ee74e9d5" xlink:to="loc_us-gaap_SecuritiesLoanedAsset_85cb1d94-eb02-4bf5-bbbd-e738660c8fc8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecurityLoanedAfterOffsetSubjectToMasterNettingArrangement_024c9fad-72bd-4f56-bf08-21e8334e09e3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecurityLoanedAfterOffsetSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingSecuritiesLoanedAbstract_54d2d08b-120c-434b-87a1-7d61ee74e9d5" xlink:to="loc_us-gaap_SecurityLoanedAfterOffsetSubjectToMasterNettingArrangement_024c9fad-72bd-4f56-bf08-21e8334e09e3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SecuritiesLoanedGrossAmountsNotOffsetAbstract_bcc17124-c176-4b55-9423-54195624c6e2" xlink:href="virt-20240930.xsd#virt_SecuritiesLoanedGrossAmountsNotOffsetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingSecuritiesLoanedAbstract_54d2d08b-120c-434b-87a1-7d61ee74e9d5" xlink:to="loc_virt_SecuritiesLoanedGrossAmountsNotOffsetAbstract_bcc17124-c176-4b55-9423-54195624c6e2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesLoanedCollateralRightToReclaimSecurities_67ff66a8-fa9f-43ba-abea-de86a8027762" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesLoanedCollateralRightToReclaimSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_SecuritiesLoanedGrossAmountsNotOffsetAbstract_bcc17124-c176-4b55-9423-54195624c6e2" xlink:to="loc_us-gaap_SecuritiesLoanedCollateralRightToReclaimSecurities_67ff66a8-fa9f-43ba-abea-de86a8027762" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesLoanedCollateralRightToReclaimCash_b05b468d-866c-4dbb-be9d-43b2eb46f4bb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesLoanedCollateralRightToReclaimCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_SecuritiesLoanedGrossAmountsNotOffsetAbstract_bcc17124-c176-4b55-9423-54195624c6e2" xlink:to="loc_us-gaap_SecuritiesLoanedCollateralRightToReclaimCash_b05b468d-866c-4dbb-be9d-43b2eb46f4bb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesLoanedOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection_8a5fbc36-8a9b-42a7-9037-ae01a041527d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesLoanedOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingSecuritiesLoanedAbstract_54d2d08b-120c-434b-87a1-7d61ee74e9d5" xlink:to="loc_us-gaap_SecuritiesLoanedOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection_8a5fbc36-8a9b-42a7-9037-ae01a041527d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_OffsettingSecuritiesSoldUnderAgreementsToRepurchaseAbstract_1aaf9d40-94a9-4c7d-9821-45870423ed66" xlink:href="virt-20240930.xsd#virt_OffsettingSecuritiesSoldUnderAgreementsToRepurchaseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingLiabilitiesLineItems_8d6e08ee-2c02-4311-9d95-9343de741904" xlink:to="loc_virt_OffsettingSecuritiesSoldUnderAgreementsToRepurchaseAbstract_1aaf9d40-94a9-4c7d-9821-45870423ed66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseGross_87eac58a-23a0-4aef-ab47-e3657ed87841" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OffsettingSecuritiesSoldUnderAgreementsToRepurchaseAbstract_1aaf9d40-94a9-4c7d-9821-45870423ed66" xlink:to="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseGross_87eac58a-23a0-4aef-ab47-e3657ed87841" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseAsset_18103ce0-e04b-46b9-8eaa-1d77f001966f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OffsettingSecuritiesSoldUnderAgreementsToRepurchaseAbstract_1aaf9d40-94a9-4c7d-9821-45870423ed66" xlink:to="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseAsset_18103ce0-e04b-46b9-8eaa-1d77f001966f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritySoldUnderAgreementToRepurchaseAfterOffsetSubjectToMasterNettingArrangement_1136273f-f9b3-40e1-b422-f390bac6cca1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritySoldUnderAgreementToRepurchaseAfterOffsetSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OffsettingSecuritiesSoldUnderAgreementsToRepurchaseAbstract_1aaf9d40-94a9-4c7d-9821-45870423ed66" xlink:to="loc_us-gaap_SecuritySoldUnderAgreementToRepurchaseAfterOffsetSubjectToMasterNettingArrangement_1136273f-f9b3-40e1-b422-f390bac6cca1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SecuritiesSoldUnderAgreementsToRepurchaseGrossAmountsNotOffsetAbstract_2acd394c-594c-47f8-8cf0-d427288f8d50" xlink:href="virt-20240930.xsd#virt_SecuritiesSoldUnderAgreementsToRepurchaseGrossAmountsNotOffsetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OffsettingSecuritiesSoldUnderAgreementsToRepurchaseAbstract_1aaf9d40-94a9-4c7d-9821-45870423ed66" xlink:to="loc_virt_SecuritiesSoldUnderAgreementsToRepurchaseGrossAmountsNotOffsetAbstract_2acd394c-594c-47f8-8cf0-d427288f8d50" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseCollateralRightToReclaimSecurities_ecade2cc-e617-460f-932b-54f0a1a35fec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseCollateralRightToReclaimSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_SecuritiesSoldUnderAgreementsToRepurchaseGrossAmountsNotOffsetAbstract_2acd394c-594c-47f8-8cf0-d427288f8d50" xlink:to="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseCollateralRightToReclaimSecurities_ecade2cc-e617-460f-932b-54f0a1a35fec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseCollateralRightToReclaimCash_feec4b96-6a03-47ad-ae42-37485521b33d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseCollateralRightToReclaimCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_SecuritiesSoldUnderAgreementsToRepurchaseGrossAmountsNotOffsetAbstract_2acd394c-594c-47f8-8cf0-d427288f8d50" xlink:to="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseCollateralRightToReclaimCash_feec4b96-6a03-47ad-ae42-37485521b33d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection_0f7f29a5-d6a4-4808-b16c-8f2b4a253d02" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OffsettingSecuritiesSoldUnderAgreementsToRepurchaseAbstract_1aaf9d40-94a9-4c7d-9821-45870423ed66" xlink:to="loc_us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection_0f7f29a5-d6a4-4808-b16c-8f2b4a253d02" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_OffsettingTradingLiabilitiesAtFairValueAbstract_c0699412-224a-4d55-83f3-326a6361365b" xlink:href="virt-20240930.xsd#virt_OffsettingTradingLiabilitiesAtFairValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingLiabilitiesLineItems_8d6e08ee-2c02-4311-9d95-9343de741904" xlink:to="loc_virt_OffsettingTradingLiabilitiesAtFairValueAbstract_c0699412-224a-4d55-83f3-326a6361365b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_97c6a6c3-fdd7-466c-a179-c3519c138bad" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OffsettingTradingLiabilitiesAtFairValueAbstract_c0699412-224a-4d55-83f3-326a6361365b" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_97c6a6c3-fdd7-466c-a179-c3519c138bad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_bbe35ee9-ba0a-4be9-8362-b7ba8dacbf82" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilityFairValueGrossAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OffsettingTradingLiabilitiesAtFairValueAbstract_c0699412-224a-4d55-83f3-326a6361365b" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_bbe35ee9-ba0a-4be9-8362-b7ba8dacbf82" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_df2291a0-293b-47a2-9193-9658093942c5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OffsettingTradingLiabilitiesAtFairValueAbstract_c0699412-224a-4d55-83f3-326a6361365b" xlink:to="loc_us-gaap_DerivativeLiabilities_df2291a0-293b-47a2-9193-9658093942c5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_DerivativeFairValueOfDerivativeLiabilityGrossAmountsNotOffsetAbstract_2de53bde-cb4c-475c-810b-9c6e5d892d3f" xlink:href="virt-20240930.xsd#virt_DerivativeFairValueOfDerivativeLiabilityGrossAmountsNotOffsetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OffsettingTradingLiabilitiesAtFairValueAbstract_c0699412-224a-4d55-83f3-326a6361365b" xlink:to="loc_virt_DerivativeFairValueOfDerivativeLiabilityGrossAmountsNotOffsetAbstract_2de53bde-cb4c-475c-810b-9c6e5d892d3f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCollateralRightToReclaimSecurities_de65eacf-d699-44a4-921f-f92fbc1182e2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeCollateralRightToReclaimSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_DerivativeFairValueOfDerivativeLiabilityGrossAmountsNotOffsetAbstract_2de53bde-cb4c-475c-810b-9c6e5d892d3f" xlink:to="loc_us-gaap_DerivativeCollateralRightToReclaimSecurities_de65eacf-d699-44a4-921f-f92fbc1182e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCollateralRightToReclaimCash_606e4fb4-adf6-47b9-b093-4e53c4353be7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeCollateralRightToReclaimCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_DerivativeFairValueOfDerivativeLiabilityGrossAmountsNotOffsetAbstract_2de53bde-cb4c-475c-810b-9c6e5d892d3f" xlink:to="loc_us-gaap_DerivativeCollateralRightToReclaimCash_606e4fb4-adf6-47b9-b093-4e53c4353be7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral_bb1d3500-252a-44b1-8578-ba3281166a91" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OffsettingTradingLiabilitiesAtFairValueAbstract_c0699412-224a-4d55-83f3-326a6361365b" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral_bb1d3500-252a-44b1-8578-ba3281166a91" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingDerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedAbstract_5be4ac80-24c8-47f2-a04a-8795d98f558c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OffsettingDerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingLiabilitiesLineItems_8d6e08ee-2c02-4311-9d95-9343de741904" xlink:to="loc_us-gaap_OffsettingDerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedAbstract_5be4ac80-24c8-47f2-a04a-8795d98f558c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedGross_cbd380b4-1ddd-41f9-b93a-7b9a720786c9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedAbstract_5be4ac80-24c8-47f2-a04a-8795d98f558c" xlink:to="loc_us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedGross_cbd380b4-1ddd-41f9-b93a-7b9a720786c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedAsset_0cb12732-6650-46db-897b-e278b9b0f165" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedAbstract_5be4ac80-24c8-47f2-a04a-8795d98f558c" xlink:to="loc_us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedAsset_0cb12732-6650-46db-897b-e278b9b0f165" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitySecuritySoldUnderAgreementToRepurchaseSecurityLoanedAfterOffsetSubjectToMasterNettingArrangement_93dd4e4c-5b13-4f69-878f-c9df75acdfbf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilitySecuritySoldUnderAgreementToRepurchaseSecurityLoanedAfterOffsetSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedAbstract_5be4ac80-24c8-47f2-a04a-8795d98f558c" xlink:to="loc_us-gaap_DerivativeLiabilitySecuritySoldUnderAgreementToRepurchaseSecurityLoanedAfterOffsetSubjectToMasterNettingArrangement_93dd4e4c-5b13-4f69-878f-c9df75acdfbf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_DerivativeLiabilitySecuritiesSoldUnderAgreementsToRepurchaseSecuritiesLoanedGrossAmountsNotOffsetAbstract_2fbbe93e-0138-4dd5-a54f-b41738fe0504" xlink:href="virt-20240930.xsd#virt_DerivativeLiabilitySecuritiesSoldUnderAgreementsToRepurchaseSecuritiesLoanedGrossAmountsNotOffsetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedAbstract_5be4ac80-24c8-47f2-a04a-8795d98f558c" xlink:to="loc_virt_DerivativeLiabilitySecuritiesSoldUnderAgreementsToRepurchaseSecuritiesLoanedGrossAmountsNotOffsetAbstract_2fbbe93e-0138-4dd5-a54f-b41738fe0504" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedCollateralRightToReclaimSecurities_926291db-e2ae-4979-84f7-6058d2b1fe6c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedCollateralRightToReclaimSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_DerivativeLiabilitySecuritiesSoldUnderAgreementsToRepurchaseSecuritiesLoanedGrossAmountsNotOffsetAbstract_2fbbe93e-0138-4dd5-a54f-b41738fe0504" xlink:to="loc_us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedCollateralRightToReclaimSecurities_926291db-e2ae-4979-84f7-6058d2b1fe6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedCollateralRightToReclaimCash_a59081c3-1ee7-4f2a-9cf1-8495b8e45eda" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedCollateralRightToReclaimCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_DerivativeLiabilitySecuritiesSoldUnderAgreementsToRepurchaseSecuritiesLoanedGrossAmountsNotOffsetAbstract_2fbbe93e-0138-4dd5-a54f-b41738fe0504" xlink:to="loc_us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedCollateralRightToReclaimCash_a59081c3-1ee7-4f2a-9cf1-8495b8e45eda" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection_a27ffb91-dbf3-4fba-8fd3-176791e8ddf5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedAbstract_5be4ac80-24c8-47f2-a04a-8795d98f558c" xlink:to="loc_us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection_a27ffb91-dbf3-4fba-8fd3-176791e8ddf5" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/FinancialAssetsandLiabilitiesGrossObligationsForSecuritiesLendingTransactionsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#FinancialAssetsandLiabilitiesGrossObligationsForSecuritiesLendingTransactionsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/FinancialAssetsandLiabilitiesGrossObligationsForSecuritiesLendingTransactionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_2fa44598-77d7-460b-b62c-671e4f4a026e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5e8422fb-f468-42d1-96c2-ce6e02b1841f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_2fa44598-77d7-460b-b62c-671e4f4a026e" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5e8422fb-f468-42d1-96c2-ce6e02b1841f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_3005879c-4d2d-49fe-b734-43531b8243c5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5e8422fb-f468-42d1-96c2-ce6e02b1841f" xlink:to="loc_us-gaap_FinancialInstrumentAxis_3005879c-4d2d-49fe-b734-43531b8243c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3005879c-4d2d-49fe-b734-43531b8243c5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_3005879c-4d2d-49fe-b734-43531b8243c5" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3005879c-4d2d-49fe-b734-43531b8243c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_418b5905-8666-4e9b-a353-9acddfcdb150" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_3005879c-4d2d-49fe-b734-43531b8243c5" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_418b5905-8666-4e9b-a353-9acddfcdb150" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesMember_0bd75e32-cadb-4b47-a171-e1f761db151f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_418b5905-8666-4e9b-a353-9acddfcdb150" xlink:to="loc_us-gaap_EquitySecuritiesMember_0bd75e32-cadb-4b47-a171-e1f761db151f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_USAndNonUSGovernmentObligationsMember_eab96369-63b9-4c13-bd6e-0801f4b1eece" xlink:href="virt-20240930.xsd#virt_USAndNonUSGovernmentObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_418b5905-8666-4e9b-a353-9acddfcdb150" xlink:to="loc_virt_USAndNonUSGovernmentObligationsMember_eab96369-63b9-4c13-bd6e-0801f4b1eece" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_56a50f12-4ef1-4f83-81ab-27c520b2c561" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5e8422fb-f468-42d1-96c2-ce6e02b1841f" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_56a50f12-4ef1-4f83-81ab-27c520b2c561" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_56a50f12-4ef1-4f83-81ab-27c520b2c561_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_56a50f12-4ef1-4f83-81ab-27c520b2c561" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_56a50f12-4ef1-4f83-81ab-27c520b2c561_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_a03faf1c-c906-4ee4-9376-273d843b4aac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_56a50f12-4ef1-4f83-81ab-27c520b2c561" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_a03faf1c-c906-4ee4-9376-273d843b4aac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_OvernightAndContinuousMember_7504409a-b4a0-432c-b897-c7db03179495" xlink:href="virt-20240930.xsd#virt_OvernightAndContinuousMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_a03faf1c-c906-4ee4-9376-273d843b4aac" xlink:to="loc_virt_OvernightAndContinuousMember_7504409a-b4a0-432c-b897-c7db03179495" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaturityUpTo30DaysMember_923af1d1-7514-4bbe-ba74-827ddfa7560c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MaturityUpTo30DaysMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_a03faf1c-c906-4ee4-9376-273d843b4aac" xlink:to="loc_us-gaap_MaturityUpTo30DaysMember_923af1d1-7514-4bbe-ba74-827ddfa7560c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_Maturity30To60DaysMember_d6815daf-3827-4697-b53c-1331f460448b" xlink:href="virt-20240930.xsd#virt_Maturity30To60DaysMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_a03faf1c-c906-4ee4-9376-273d843b4aac" xlink:to="loc_virt_Maturity30To60DaysMember_d6815daf-3827-4697-b53c-1331f460448b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_Maturity61To90DaysMember_14172978-142b-4249-a0af-a4608869385a" xlink:href="virt-20240930.xsd#virt_Maturity61To90DaysMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_a03faf1c-c906-4ee4-9376-273d843b4aac" xlink:to="loc_virt_Maturity61To90DaysMember_14172978-142b-4249-a0af-a4608869385a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaturityOver90DaysMember_93b114d6-e9f8-4561-b9e8-11c71553784a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MaturityOver90DaysMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_a03faf1c-c906-4ee4-9376-273d843b4aac" xlink:to="loc_us-gaap_MaturityOver90DaysMember_93b114d6-e9f8-4561-b9e8-11c71553784a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RepurchaseAgreementRemainingContractualMaturity_01da981a-7fbf-44bf-a16d-787f953ce91d" xlink:href="virt-20240930.xsd#virt_RepurchaseAgreementRemainingContractualMaturity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_2fa44598-77d7-460b-b62c-671e4f4a026e" xlink:to="loc_virt_RepurchaseAgreementRemainingContractualMaturity_01da981a-7fbf-44bf-a16d-787f953ce91d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SecuritiesLendingTransactionRemainingContractualMaturity_c539fb1e-f565-4cf1-890f-ddc883fefa6a" xlink:href="virt-20240930.xsd#virt_SecuritiesLendingTransactionRemainingContractualMaturity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_2fa44598-77d7-460b-b62c-671e4f4a026e" xlink:to="loc_virt_SecuritiesLendingTransactionRemainingContractualMaturity_c539fb1e-f565-4cf1-890f-ddc883fefa6a" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/DerivativeInstrumentsFairValueofDerivativeInstrumentsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#DerivativeInstrumentsFairValueofDerivativeInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/DerivativeInstrumentsFairValueofDerivativeInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_654b0062-5b3a-4dbe-b9d0-67976f9fb23a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_3f0849db-5848-4881-9537-d41d48ae3dfc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_654b0062-5b3a-4dbe-b9d0-67976f9fb23a" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_3f0849db-5848-4881-9537-d41d48ae3dfc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_feab3acc-b51d-4094-a0c7-0da485be058f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_3f0849db-5848-4881-9537-d41d48ae3dfc" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_feab3acc-b51d-4094-a0c7-0da485be058f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_feab3acc-b51d-4094-a0c7-0da485be058f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_feab3acc-b51d-4094-a0c7-0da485be058f" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_feab3acc-b51d-4094-a0c7-0da485be058f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_fd7cd8ec-2d4c-4ff5-9da2-45be48f13979" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_feab3acc-b51d-4094-a0c7-0da485be058f" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_fd7cd8ec-2d4c-4ff5-9da2-45be48f13979" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_EquitiesFuturesMember_7cc37a05-4d1b-42c1-aec9-e9bf003c2ce0" xlink:href="virt-20240930.xsd#virt_EquitiesFuturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_fd7cd8ec-2d4c-4ff5-9da2-45be48f13979" xlink:to="loc_virt_EquitiesFuturesMember_7cc37a05-4d1b-42c1-aec9-e9bf003c2ce0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_542d2568-187f-445c-8941-d2b6f33d78ec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_fd7cd8ec-2d4c-4ff5-9da2-45be48f13979" xlink:to="loc_us-gaap_CommodityContractMember_542d2568-187f-445c-8941-d2b6f33d78ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeFutureMember_90e20281-e241-45b3-9bb6-33b94d027bc0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeFutureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_fd7cd8ec-2d4c-4ff5-9da2-45be48f13979" xlink:to="loc_us-gaap_ForeignExchangeFutureMember_90e20281-e241-45b3-9bb6-33b94d027bc0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FixedIncomeInterestRateMember_afc26a20-0c9e-4a91-8e8c-87abe501989a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FixedIncomeInterestRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_fd7cd8ec-2d4c-4ff5-9da2-45be48f13979" xlink:to="loc_us-gaap_FixedIncomeInterestRateMember_afc26a20-0c9e-4a91-8e8c-87abe501989a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OptionMember_60a0a7f4-2b02-4baf-9330-00e6290fa054" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_fd7cd8ec-2d4c-4ff5-9da2-45be48f13979" xlink:to="loc_us-gaap_OptionMember_60a0a7f4-2b02-4baf-9330-00e6290fa054" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_e5950e17-f735-4785-b1f7-e66aea689444" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_fd7cd8ec-2d4c-4ff5-9da2-45be48f13979" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_e5950e17-f735-4785-b1f7-e66aea689444" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_93880bb8-f096-4823-bfd2-4e841cfb2161" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_fd7cd8ec-2d4c-4ff5-9da2-45be48f13979" xlink:to="loc_us-gaap_InterestRateSwapMember_93880bb8-f096-4823-bfd2-4e841cfb2161" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_7f71ce54-9c63-43ec-a3c8-b3356c6331bb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_3f0849db-5848-4881-9537-d41d48ae3dfc" xlink:to="loc_us-gaap_HedgingDesignationAxis_7f71ce54-9c63-43ec-a3c8-b3356c6331bb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_7f71ce54-9c63-43ec-a3c8-b3356c6331bb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_7f71ce54-9c63-43ec-a3c8-b3356c6331bb" xlink:to="loc_us-gaap_HedgingDesignationDomain_7f71ce54-9c63-43ec-a3c8-b3356c6331bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_63db8fb8-6594-4532-93ec-db65dba62c1a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_7f71ce54-9c63-43ec-a3c8-b3356c6331bb" xlink:to="loc_us-gaap_HedgingDesignationDomain_63db8fb8-6594-4532-93ec-db65dba62c1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_92750707-1cc9-4ec4-8ffb-75d52aae4540" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_63db8fb8-6594-4532-93ec-db65dba62c1a" xlink:to="loc_us-gaap_NondesignatedMember_92750707-1cc9-4ec4-8ffb-75d52aae4540" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_8f398721-742a-46a9-bbe3-e6c099f57950" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_63db8fb8-6594-4532-93ec-db65dba62c1a" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_8f398721-742a-46a9-bbe3-e6c099f57950" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_3070d656-9a72-4fe1-a251-21a2283f0168" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_3f0849db-5848-4881-9537-d41d48ae3dfc" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_3070d656-9a72-4fe1-a251-21a2283f0168" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_3070d656-9a72-4fe1-a251-21a2283f0168_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_3070d656-9a72-4fe1-a251-21a2283f0168" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_3070d656-9a72-4fe1-a251-21a2283f0168_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_840ccc9f-ad68-413d-8002-d0f8c650f86f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_3070d656-9a72-4fe1-a251-21a2283f0168" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_840ccc9f-ad68-413d-8002-d0f8c650f86f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ReceivablesFromBrokerDealersAndClearingOrganizationsMember_e80f9a01-ba7c-4720-a2b5-74761333a5ec" xlink:href="virt-20240930.xsd#virt_ReceivablesFromBrokerDealersAndClearingOrganizationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_840ccc9f-ad68-413d-8002-d0f8c650f86f" xlink:to="loc_virt_ReceivablesFromBrokerDealersAndClearingOrganizationsMember_e80f9a01-ba7c-4720-a2b5-74761333a5ec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_FinancialInstrumentsOwnedMember_c318731b-db0d-4ca6-89ba-e9d910b3f2d3" xlink:href="virt-20240930.xsd#virt_FinancialInstrumentsOwnedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_840ccc9f-ad68-413d-8002-d0f8c650f86f" xlink:to="loc_virt_FinancialInstrumentsOwnedMember_c318731b-db0d-4ca6-89ba-e9d910b3f2d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_PayablesToBrokerDealersAndClearingOrganizationsMember_6d8b2859-2432-4383-871a-422fecc32863" xlink:href="virt-20240930.xsd#virt_PayablesToBrokerDealersAndClearingOrganizationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_840ccc9f-ad68-413d-8002-d0f8c650f86f" xlink:to="loc_virt_PayablesToBrokerDealersAndClearingOrganizationsMember_6d8b2859-2432-4383-871a-422fecc32863" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesSoldNotYetPurchasedMember_3f9fcc24-cbce-42ba-83b4-72fbcbafad88" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuritiesSoldNotYetPurchasedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_840ccc9f-ad68-413d-8002-d0f8c650f86f" xlink:to="loc_us-gaap_SecuritiesSoldNotYetPurchasedMember_3f9fcc24-cbce-42ba-83b4-72fbcbafad88" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsAbstract_28a96273-c32d-44f6-b2df-f3664b9ada95" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_654b0062-5b3a-4dbe-b9d0-67976f9fb23a" xlink:to="loc_us-gaap_DerivativeAssetsAbstract_28a96273-c32d-44f6-b2df-f3664b9ada95" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_083892df-ea89-4414-a8da-8e6d7c095ff6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeAssetsAbstract_28a96273-c32d-44f6-b2df-f3664b9ada95" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_083892df-ea89-4414-a8da-8e6d7c095ff6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetNotionalAmount_bead8c45-c98a-4424-8e39-140a7c290d89" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssetNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeAssetsAbstract_28a96273-c32d-44f6-b2df-f3664b9ada95" xlink:to="loc_us-gaap_DerivativeAssetNotionalAmount_bead8c45-c98a-4424-8e39-140a7c290d89" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesAbstract_f10f3a75-542f-4eda-a621-e6dc18a1d3ee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_654b0062-5b3a-4dbe-b9d0-67976f9fb23a" xlink:to="loc_us-gaap_DerivativeLiabilitiesAbstract_f10f3a75-542f-4eda-a621-e6dc18a1d3ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_c49eb445-1c52-491b-8ca5-971c64597efa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLiabilitiesAbstract_f10f3a75-542f-4eda-a621-e6dc18a1d3ee" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_c49eb445-1c52-491b-8ca5-971c64597efa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityNotionalAmount_c069a88b-b0ef-4ad9-beb6-0e7c00b38809" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilityNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLiabilitiesAbstract_f10f3a75-542f-4eda-a621-e6dc18a1d3ee" xlink:to="loc_us-gaap_DerivativeLiabilityNotionalAmount_c069a88b-b0ef-4ad9-beb6-0e7c00b38809" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/DerivativeInstrumentsGainLossFromDerivativeInstrumentsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#DerivativeInstrumentsGainLossFromDerivativeInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/DerivativeInstrumentsGainLossFromDerivativeInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_8efe4234-a2b5-4070-9961-969ef161ff70" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_f84bbf1f-4ed6-4dd0-b90e-bd9b1d81cd5e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_8efe4234-a2b5-4070-9961-969ef161ff70" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_f84bbf1f-4ed6-4dd0-b90e-bd9b1d81cd5e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_d1d79c3e-1e6e-4806-bff8-d1f23093fa1c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_f84bbf1f-4ed6-4dd0-b90e-bd9b1d81cd5e" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_d1d79c3e-1e6e-4806-bff8-d1f23093fa1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_d1d79c3e-1e6e-4806-bff8-d1f23093fa1c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_d1d79c3e-1e6e-4806-bff8-d1f23093fa1c" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_d1d79c3e-1e6e-4806-bff8-d1f23093fa1c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_0ed7c6b9-b8d3-46b4-a3f1-55664083827e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_d1d79c3e-1e6e-4806-bff8-d1f23093fa1c" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_0ed7c6b9-b8d3-46b4-a3f1-55664083827e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FutureMember_3c477f2a-874b-4b24-95d0-f5e07106e04f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FutureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_0ed7c6b9-b8d3-46b4-a3f1-55664083827e" xlink:to="loc_us-gaap_FutureMember_3c477f2a-874b-4b24-95d0-f5e07106e04f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_be7c5a84-6d89-4bd1-9ee1-9fe98759cbb7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_0ed7c6b9-b8d3-46b4-a3f1-55664083827e" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_be7c5a84-6d89-4bd1-9ee1-9fe98759cbb7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OptionMember_8860bcc4-b38a-4be7-ba3c-3db04f569588" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_0ed7c6b9-b8d3-46b4-a3f1-55664083827e" xlink:to="loc_us-gaap_OptionMember_8860bcc4-b38a-4be7-ba3c-3db04f569588" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_dc53cb3d-3cb8-46a3-bc3d-08f044b5d1f8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_0ed7c6b9-b8d3-46b4-a3f1-55664083827e" xlink:to="loc_us-gaap_InterestRateSwapMember_dc53cb3d-3cb8-46a3-bc3d-08f044b5d1f8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_TerminatedInterestRateSwapsMember_f8ad81a9-7d6e-4063-89af-17cdc600627c" xlink:href="virt-20240930.xsd#virt_TerminatedInterestRateSwapsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_0ed7c6b9-b8d3-46b4-a3f1-55664083827e" xlink:to="loc_virt_TerminatedInterestRateSwapsMember_f8ad81a9-7d6e-4063-89af-17cdc600627c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_16dfa6b4-773c-4e4d-804d-fc48d433eadf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_f84bbf1f-4ed6-4dd0-b90e-bd9b1d81cd5e" xlink:to="loc_us-gaap_HedgingDesignationAxis_16dfa6b4-773c-4e4d-804d-fc48d433eadf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_16dfa6b4-773c-4e4d-804d-fc48d433eadf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_16dfa6b4-773c-4e4d-804d-fc48d433eadf" xlink:to="loc_us-gaap_HedgingDesignationDomain_16dfa6b4-773c-4e4d-804d-fc48d433eadf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_f9079907-ad07-45cd-91da-6b0156a4e1f9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_16dfa6b4-773c-4e4d-804d-fc48d433eadf" xlink:to="loc_us-gaap_HedgingDesignationDomain_f9079907-ad07-45cd-91da-6b0156a4e1f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_9cc0df72-fd86-4384-ab09-b49134718658" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_f9079907-ad07-45cd-91da-6b0156a4e1f9" xlink:to="loc_us-gaap_NondesignatedMember_9cc0df72-fd86-4384-ab09-b49134718658" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_c83e5535-8cdc-40eb-ba9d-c041612d5aab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_f9079907-ad07-45cd-91da-6b0156a4e1f9" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_c83e5535-8cdc-40eb-ba9d-c041612d5aab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNet_735f5e5b-10ad-4098-adc6-dced8f4c0a02" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeGainLossOnDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_8efe4234-a2b5-4070-9961-969ef161ff70" xlink:to="loc_us-gaap_DerivativeGainLossOnDerivativeNet_735f5e5b-10ad-4098-adc6-dced8f4c0a02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax_348e05a0-0c8b-40bf-bd5d-57fbe7b3e7da" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_8efe4234-a2b5-4070-9961-969ef161ff70" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax_348e05a0-0c8b-40bf-bd5d-57fbe7b3e7da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTermOfContract_1041cc6d-b80b-4e27-913c-79e5079b1b20" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_8efe4234-a2b5-4070-9961-969ef161ff70" xlink:to="loc_us-gaap_DerivativeTermOfContract_1041cc6d-b80b-4e27-913c-79e5079b1b20" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_61f09e98-9ea0-4764-8994-d00553948fb9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_8efe4234-a2b5-4070-9961-969ef161ff70" xlink:to="loc_us-gaap_DerivativeNotionalAmount_61f09e98-9ea0-4764-8994-d00553948fb9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainOnDerivativeInstrumentsPretax_2d2ee445-4c15-454a-8046-a829627a6346" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GainOnDerivativeInstrumentsPretax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_8efe4234-a2b5-4070-9961-969ef161ff70" xlink:to="loc_us-gaap_GainOnDerivativeInstrumentsPretax_2d2ee445-4c15-454a-8046-a829627a6346" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/VariableInterestEntitiesAdditionalInformationDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#VariableInterestEntitiesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/VariableInterestEntitiesAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityLineItems_4560e411-71bc-46c2-a473-368bbf54fb37" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableInterestEntityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_be163530-0908-4c41-a5d1-8bab52fc7d5e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfVariableInterestEntitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_4560e411-71bc-46c2-a473-368bbf54fb37" xlink:to="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_be163530-0908-4c41-a5d1-8bab52fc7d5e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_acb38208-3126-480f-98d4-d2fd88f5c4b5" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_be163530-0908-4c41-a5d1-8bab52fc7d5e" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_acb38208-3126-480f-98d4-d2fd88f5c4b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_acb38208-3126-480f-98d4-d2fd88f5c4b5_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_acb38208-3126-480f-98d4-d2fd88f5c4b5" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_acb38208-3126-480f-98d4-d2fd88f5c4b5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_95260fc0-e18d-486e-925b-796325f69f5f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_acb38208-3126-480f-98d4-d2fd88f5c4b5" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_95260fc0-e18d-486e-925b-796325f69f5f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_JointVentureBuildingMicrowaveCommunicationNetworksInUSAndEuropeMember_242babf9-df1a-481d-a331-c63b422e63c6" xlink:href="virt-20240930.xsd#virt_JointVentureBuildingMicrowaveCommunicationNetworksInUSAndEuropeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_95260fc0-e18d-486e-925b-796325f69f5f" xlink:to="loc_virt_JointVentureBuildingMicrowaveCommunicationNetworksInUSAndEuropeMember_242babf9-df1a-481d-a331-c63b422e63c6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_JointVentureBuildingMicrowaveCommunicationNetworksInUSAndAsiaMember_80984f77-75eb-4972-aff6-fb9448414dc8" xlink:href="virt-20240930.xsd#virt_JointVentureBuildingMicrowaveCommunicationNetworksInUSAndAsiaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_95260fc0-e18d-486e-925b-796325f69f5f" xlink:to="loc_virt_JointVentureBuildingMicrowaveCommunicationNetworksInUSAndAsiaMember_80984f77-75eb-4972-aff6-fb9448414dc8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_JointVentureOfferingDerivativesTradingTechnologyAndExecutionServicesMember_f163061f-403d-4fde-b706-d2e585f182bf" xlink:href="virt-20240930.xsd#virt_JointVentureOfferingDerivativesTradingTechnologyAndExecutionServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_95260fc0-e18d-486e-925b-796325f69f5f" xlink:to="loc_virt_JointVentureOfferingDerivativesTradingTechnologyAndExecutionServicesMember_f163061f-403d-4fde-b706-d2e585f182bf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_JointVentureDevelopingAMemberOwnedEquitiesExchangeWithTheGoalOfIncreasingCompetitionMember_dcf30926-bdef-4792-be95-1715e7312c40" xlink:href="virt-20240930.xsd#virt_JointVentureDevelopingAMemberOwnedEquitiesExchangeWithTheGoalOfIncreasingCompetitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_95260fc0-e18d-486e-925b-796325f69f5f" xlink:to="loc_virt_JointVentureDevelopingAMemberOwnedEquitiesExchangeWithTheGoalOfIncreasingCompetitionMember_dcf30926-bdef-4792-be95-1715e7312c40" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_JointVentureDevelopingAndOperatingCryptocurrencyTradingPlatformMember_24175f81-5116-48f0-a010-cc9a31e6a806" xlink:href="virt-20240930.xsd#virt_JointVentureDevelopingAndOperatingCryptocurrencyTradingPlatformMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_95260fc0-e18d-486e-925b-796325f69f5f" xlink:to="loc_virt_JointVentureDevelopingAndOperatingCryptocurrencyTradingPlatformMember_24175f81-5116-48f0-a010-cc9a31e6a806" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_JointVentureFormedToSupportGrowthAndExpansionOfMultiAssetRequestForQuoteCommunicationPlatformMember_ab9e4e06-ebe9-4889-aecc-8d89cf114a8a" xlink:href="virt-20240930.xsd#virt_JointVentureFormedToSupportGrowthAndExpansionOfMultiAssetRequestForQuoteCommunicationPlatformMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_95260fc0-e18d-486e-925b-796325f69f5f" xlink:to="loc_virt_JointVentureFormedToSupportGrowthAndExpansionOfMultiAssetRequestForQuoteCommunicationPlatformMember_ab9e4e06-ebe9-4889-aecc-8d89cf114a8a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_c58c6089-3aa9-4218-80e8-0a8c40f55fb0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_be163530-0908-4c41-a5d1-8bab52fc7d5e" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_c58c6089-3aa9-4218-80e8-0a8c40f55fb0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_c58c6089-3aa9-4218-80e8-0a8c40f55fb0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_c58c6089-3aa9-4218-80e8-0a8c40f55fb0" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_c58c6089-3aa9-4218-80e8-0a8c40f55fb0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_58625ee5-1f84-43f4-94aa-75bcc52aba00" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_c58c6089-3aa9-4218-80e8-0a8c40f55fb0" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_58625ee5-1f84-43f4-94aa-75bcc52aba00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_f65a4c04-8a97-43ac-a9ed-6f7d1e576756" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_58625ee5-1f84-43f4-94aa-75bcc52aba00" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_f65a4c04-8a97-43ac-a9ed-6f7d1e576756" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_82eec49a-7ef9-428c-a67a-6506cfcecd72" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_be163530-0908-4c41-a5d1-8bab52fc7d5e" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_82eec49a-7ef9-428c-a67a-6506cfcecd72" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_82eec49a-7ef9-428c-a67a-6506cfcecd72_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_82eec49a-7ef9-428c-a67a-6506cfcecd72" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_82eec49a-7ef9-428c-a67a-6506cfcecd72_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_0ad4297f-b8c2-4fb6-a9ad-bc182fd28239" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_82eec49a-7ef9-428c-a67a-6506cfcecd72" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_0ad4297f-b8c2-4fb6-a9ad-bc182fd28239" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RFQHubMember_89a25889-7108-4a99-bcd5-aa5bd668928f" xlink:href="virt-20240930.xsd#virt_RFQHubMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_0ad4297f-b8c2-4fb6-a9ad-bc182fd28239" xlink:to="loc_virt_RFQHubMember_89a25889-7108-4a99-bcd5-aa5bd668928f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_06da0261-f8ac-4ee9-ad3e-41f210ab8b11" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_4560e411-71bc-46c2-a473-368bbf54fb37" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_06da0261-f8ac-4ee9-ad3e-41f210ab8b11" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_PercentageOwnershipOfEquityOfJointVentureHeldByEachInvestor_eadb4468-cad1-4eee-9dba-77edb2f898cb" xlink:href="virt-20240930.xsd#virt_PercentageOwnershipOfEquityOfJointVentureHeldByEachInvestor"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_4560e411-71bc-46c2-a473-368bbf54fb37" xlink:to="loc_virt_PercentageOwnershipOfEquityOfJointVentureHeldByEachInvestor_eadb4468-cad1-4eee-9dba-77edb2f898cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_DisposalGroupIncludingDiscontinuedOperationDivestitureOfInterestInJointVenturePercentage_1566c9c2-f268-4381-b967-a7ddf9a52b9d" xlink:href="virt-20240930.xsd#virt_DisposalGroupIncludingDiscontinuedOperationDivestitureOfInterestInJointVenturePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_4560e411-71bc-46c2-a473-368bbf54fb37" xlink:to="loc_virt_DisposalGroupIncludingDiscontinuedOperationDivestitureOfInterestInJointVenturePercentage_1566c9c2-f268-4381-b967-a7ddf9a52b9d" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/VariableInterestEntitiesNonconsolidatedVIEsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#VariableInterestEntitiesNonconsolidatedVIEsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/VariableInterestEntitiesNonconsolidatedVIEsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityLineItems_7f6b786a-fedf-4afe-9bee-7e25d799d149" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableInterestEntityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_e779f62c-c98a-43c7-9236-eb2d5bcb5c2d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfVariableInterestEntitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_7f6b786a-fedf-4afe-9bee-7e25d799d149" xlink:to="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_e779f62c-c98a-43c7-9236-eb2d5bcb5c2d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_7d903173-80a9-492d-8dfc-52ffac34e5cd" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_e779f62c-c98a-43c7-9236-eb2d5bcb5c2d" xlink:to="loc_srt_ConsolidatedEntitiesAxis_7d903173-80a9-492d-8dfc-52ffac34e5cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_7d903173-80a9-492d-8dfc-52ffac34e5cd_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_7d903173-80a9-492d-8dfc-52ffac34e5cd" xlink:to="loc_srt_ConsolidatedEntitiesDomain_7d903173-80a9-492d-8dfc-52ffac34e5cd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_47e3f0e3-7013-4915-be16-6f2dc5f11a86" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_7d903173-80a9-492d-8dfc-52ffac34e5cd" xlink:to="loc_srt_ConsolidatedEntitiesDomain_47e3f0e3-7013-4915-be16-6f2dc5f11a86" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember_13dd35cb-7a4b-4b84-a2e5-96ad400ad25c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_47e3f0e3-7013-4915-be16-6f2dc5f11a86" xlink:to="loc_us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember_13dd35cb-7a4b-4b84-a2e5-96ad400ad25c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_db458c6c-c4db-44de-872f-3b353f048557" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_7f6b786a-fedf-4afe-9bee-7e25d799d149" xlink:to="loc_us-gaap_Assets_db458c6c-c4db-44de-872f-3b353f048557" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_22472dc4-3cee-496f-831e-50d2e6fe43c1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_7f6b786a-fedf-4afe-9bee-7e25d799d149" xlink:to="loc_us-gaap_Liabilities_22472dc4-3cee-496f-831e-50d2e6fe43c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount_6286eece-847c-4273-b396-96787ec5dec6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_7f6b786a-fedf-4afe-9bee-7e25d799d149" xlink:to="loc_us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount_6286eece-847c-4273-b396-96787ec5dec6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VariableInterestEntityNonconsolidatedEntitiesAssets_a5ee04b5-3737-412b-9d5d-746b92ed1558" xlink:href="virt-20240930.xsd#virt_VariableInterestEntityNonconsolidatedEntitiesAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_7f6b786a-fedf-4afe-9bee-7e25d799d149" xlink:to="loc_virt_VariableInterestEntityNonconsolidatedEntitiesAssets_a5ee04b5-3737-412b-9d5d-746b92ed1558" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/RevenuefromContractwithCustomersDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#RevenuefromContractwithCustomersDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/RevenuefromContractwithCustomersDisaggregationofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_1e2c58a6-2148-4c54-84b5-00d538f4f2af" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_40ab2df4-d4fd-49ca-acd4-c6f86d07fc83" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1e2c58a6-2148-4c54-84b5-00d538f4f2af" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_40ab2df4-d4fd-49ca-acd4-c6f86d07fc83" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_5e53f98c-fc14-4c48-b448-7f3d21539e52" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_40ab2df4-d4fd-49ca-acd4-c6f86d07fc83" xlink:to="loc_srt_ConsolidationItemsAxis_5e53f98c-fc14-4c48-b448-7f3d21539e52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_5e53f98c-fc14-4c48-b448-7f3d21539e52_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_5e53f98c-fc14-4c48-b448-7f3d21539e52" xlink:to="loc_srt_ConsolidationItemsDomain_5e53f98c-fc14-4c48-b448-7f3d21539e52_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_8bacdcb5-b0e1-423f-a901-49171900ecfa" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_5e53f98c-fc14-4c48-b448-7f3d21539e52" xlink:to="loc_srt_ConsolidationItemsDomain_8bacdcb5-b0e1-423f-a901-49171900ecfa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_0367b198-d37c-437b-ba36-fb4c4637469e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_8bacdcb5-b0e1-423f-a901-49171900ecfa" xlink:to="loc_us-gaap_OperatingSegmentsMember_0367b198-d37c-437b-ba36-fb4c4637469e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_db9af956-5abf-45d0-8d3e-1045a490b0a2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_8bacdcb5-b0e1-423f-a901-49171900ecfa" xlink:to="loc_us-gaap_CorporateNonSegmentMember_db9af956-5abf-45d0-8d3e-1045a490b0a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_1a3aa462-ed9c-4c8b-a73b-9aeb0ac4ceee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_40ab2df4-d4fd-49ca-acd4-c6f86d07fc83" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_1a3aa462-ed9c-4c8b-a73b-9aeb0ac4ceee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_1a3aa462-ed9c-4c8b-a73b-9aeb0ac4ceee_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_1a3aa462-ed9c-4c8b-a73b-9aeb0ac4ceee" xlink:to="loc_us-gaap_SegmentDomain_1a3aa462-ed9c-4c8b-a73b-9aeb0ac4ceee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_4aa65cc1-4b63-46e6-885a-c79c19d3bbb8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_1a3aa462-ed9c-4c8b-a73b-9aeb0ac4ceee" xlink:to="loc_us-gaap_SegmentDomain_4aa65cc1-4b63-46e6-885a-c79c19d3bbb8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_MarketMakingSegmentMember_d1af3d26-9d67-4965-85dc-0b96127d4ccd" xlink:href="virt-20240930.xsd#virt_MarketMakingSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_4aa65cc1-4b63-46e6-885a-c79c19d3bbb8" xlink:to="loc_virt_MarketMakingSegmentMember_d1af3d26-9d67-4965-85dc-0b96127d4ccd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ExecutionServicesSegmentMember_7e5e3575-82ae-49aa-b8e0-10b43097481f" xlink:href="virt-20240930.xsd#virt_ExecutionServicesSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_4aa65cc1-4b63-46e6-885a-c79c19d3bbb8" xlink:to="loc_virt_ExecutionServicesSegmentMember_7e5e3575-82ae-49aa-b8e0-10b43097481f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_0be165f9-13e4-4198-a416-42480c240c86" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_40ab2df4-d4fd-49ca-acd4-c6f86d07fc83" xlink:to="loc_srt_ProductOrServiceAxis_0be165f9-13e4-4198-a416-42480c240c86" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_0be165f9-13e4-4198-a416-42480c240c86_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_0be165f9-13e4-4198-a416-42480c240c86" xlink:to="loc_srt_ProductsAndServicesDomain_0be165f9-13e4-4198-a416-42480c240c86_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_77ca4fea-a89c-4f1c-8daa-0e2290559de5" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_0be165f9-13e4-4198-a416-42480c240c86" xlink:to="loc_srt_ProductsAndServicesDomain_77ca4fea-a89c-4f1c-8daa-0e2290559de5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_CommissionsNetMember_622fb520-80cb-4763-9e90-6dcde8aa1fef" xlink:href="virt-20240930.xsd#virt_CommissionsNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_77ca4fea-a89c-4f1c-8daa-0e2290559de5" xlink:to="loc_virt_CommissionsNetMember_622fb520-80cb-4763-9e90-6dcde8aa1fef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_WorkflowTechnologyMember_23c9d648-1bbc-4b59-99bc-5b90a63b5514" xlink:href="virt-20240930.xsd#virt_WorkflowTechnologyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_77ca4fea-a89c-4f1c-8daa-0e2290559de5" xlink:to="loc_virt_WorkflowTechnologyMember_23c9d648-1bbc-4b59-99bc-5b90a63b5514" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_AnalyticsMember_c94642fb-b47c-45f4-9514-9705312b776d" xlink:href="virt-20240930.xsd#virt_AnalyticsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_77ca4fea-a89c-4f1c-8daa-0e2290559de5" xlink:to="loc_virt_AnalyticsMember_c94642fb-b47c-45f4-9514-9705312b776d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_OtherSourcesMember_7ddcb879-6ca4-4fe7-a473-61465611e8ce" xlink:href="virt-20240930.xsd#virt_OtherSourcesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_77ca4fea-a89c-4f1c-8daa-0e2290559de5" xlink:to="loc_virt_OtherSourcesMember_7ddcb879-6ca4-4fe7-a473-61465611e8ce" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_3e66292a-9ed0-45f6-815f-0bfff61abc88" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimingOfTransferOfGoodOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_40ab2df4-d4fd-49ca-acd4-c6f86d07fc83" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_3e66292a-9ed0-45f6-815f-0bfff61abc88" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_3e66292a-9ed0-45f6-815f-0bfff61abc88_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_3e66292a-9ed0-45f6-815f-0bfff61abc88" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_3e66292a-9ed0-45f6-815f-0bfff61abc88_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_5610be33-93c4-4ddf-b3b5-3bd7daab599f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_3e66292a-9ed0-45f6-815f-0bfff61abc88" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_5610be33-93c4-4ddf-b3b5-3bd7daab599f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferredAtPointInTimeMember_18a9a092-2118-461a-86e7-dd358e3f8ee7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransferredAtPointInTimeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_5610be33-93c4-4ddf-b3b5-3bd7daab599f" xlink:to="loc_us-gaap_TransferredAtPointInTimeMember_18a9a092-2118-461a-86e7-dd358e3f8ee7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferredOverTimeMember_794b2abe-d159-4efb-af81-15a35176153d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransferredOverTimeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_5610be33-93c4-4ddf-b3b5-3bd7daab599f" xlink:to="loc_us-gaap_TransferredOverTimeMember_794b2abe-d159-4efb-af81-15a35176153d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_fc649b0b-e9ab-4bce-91b8-cf2bef82fb59" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1e2c58a6-2148-4c54-84b5-00d538f4f2af" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_fc649b0b-e9ab-4bce-91b8-cf2bef82fb59" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueNotFromContractWithCustomer_048efb65-9fb8-4e3e-9c8c-e41be7a1ff5f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueNotFromContractWithCustomer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1e2c58a6-2148-4c54-84b5-00d538f4f2af" xlink:to="loc_us-gaap_RevenueNotFromContractWithCustomer_048efb65-9fb8-4e3e-9c8c-e41be7a1ff5f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_1fde0d74-fa8d-4d93-9c9c-68d6131c95a2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_1e2c58a6-2148-4c54-84b5-00d538f4f2af" xlink:to="loc_us-gaap_Revenues_1fde0d74-fa8d-4d93-9c9c-68d6131c95a2" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/IncomeTaxesDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#IncomeTaxesDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/IncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardLineItems_1933db73-e018-4e64-ba27-914f4fe3f58c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TaxCreditCarryforwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardTable_5304439f-17d5-4048-be9d-e48921d3d927" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TaxCreditCarryforwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_1933db73-e018-4e64-ba27-914f4fe3f58c" xlink:to="loc_us-gaap_TaxCreditCarryforwardTable_5304439f-17d5-4048-be9d-e48921d3d927" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_d40e1962-00dd-4a80-ba6e-144a7a5daee7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TaxCreditCarryforwardTable_5304439f-17d5-4048-be9d-e48921d3d927" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_d40e1962-00dd-4a80-ba6e-144a7a5daee7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d40e1962-00dd-4a80-ba6e-144a7a5daee7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_d40e1962-00dd-4a80-ba6e-144a7a5daee7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d40e1962-00dd-4a80-ba6e-144a7a5daee7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2d17c625-83c5-4039-a6ff-62e8440ae15e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_d40e1962-00dd-4a80-ba6e-144a7a5daee7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2d17c625-83c5-4039-a6ff-62e8440ae15e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_InvestmentTechnologyGroupInc.Member_fb9d15ed-1944-4751-9542-dc230d257578" xlink:href="virt-20240930.xsd#virt_InvestmentTechnologyGroupInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2d17c625-83c5-4039-a6ff-62e8440ae15e" xlink:to="loc_virt_InvestmentTechnologyGroupInc.Member_fb9d15ed-1944-4751-9542-dc230d257578" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_KcgHoldingsMember_d740af66-c32b-475a-9168-b9bb1ba52014" xlink:href="virt-20240930.xsd#virt_KcgHoldingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2d17c625-83c5-4039-a6ff-62e8440ae15e" xlink:to="loc_virt_KcgHoldingsMember_d740af66-c32b-475a-9168-b9bb1ba52014" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_9f4e4f83-c68f-424b-96ed-1d5b85510113" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TaxCreditCarryforwardTable_5304439f-17d5-4048-be9d-e48921d3d927" xlink:to="loc_srt_StatementGeographicalAxis_9f4e4f83-c68f-424b-96ed-1d5b85510113" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_9f4e4f83-c68f-424b-96ed-1d5b85510113_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_9f4e4f83-c68f-424b-96ed-1d5b85510113" xlink:to="loc_srt_SegmentGeographicalDomain_9f4e4f83-c68f-424b-96ed-1d5b85510113_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_1c830ffc-1e39-489e-9b8c-e9b7d16baa37" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_9f4e4f83-c68f-424b-96ed-1d5b85510113" xlink:to="loc_srt_SegmentGeographicalDomain_1c830ffc-1e39-489e-9b8c-e9b7d16baa37" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_24df6747-bc32-4076-a7c6-ba98f127ed75" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_1c830ffc-1e39-489e-9b8c-e9b7d16baa37" xlink:to="loc_us-gaap_NonUsMember_24df6747-bc32-4076-a7c6-ba98f127ed75" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_1fcdc507-2685-411d-b778-3982015daf51" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_1933db73-e018-4e64-ba27-914f4fe3f58c" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_1fcdc507-2685-411d-b778-3982015daf51" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_166ed051-0469-43b6-aa22-83b286425e0b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_1933db73-e018-4e64-ba27-914f4fe3f58c" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_166ed051-0469-43b6-aa22-83b286425e0b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesReceivable_1dc4da1d-cddf-4c60-9a7c-96a6fe634504" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxesReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_1933db73-e018-4e64-ba27-914f4fe3f58c" xlink:to="loc_us-gaap_IncomeTaxesReceivable_1dc4da1d-cddf-4c60-9a7c-96a6fe634504" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxesPayableCurrent_d570b71e-5e9d-4523-a1b0-7eb952fd64d2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TaxesPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_1933db73-e018-4e64-ba27-914f4fe3f58c" xlink:to="loc_us-gaap_TaxesPayableCurrent_d570b71e-5e9d-4523-a1b0-7eb952fd64d2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_d178fce3-a30b-4a90-8e43-ed53a314d833" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_1933db73-e018-4e64-ba27-914f4fe3f58c" xlink:to="loc_us-gaap_OperatingLossCarryforwards_d178fce3-a30b-4a90-8e43-ed53a314d833" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_cdb39596-d461-4d15-b2dc-421832ade63f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_1933db73-e018-4e64-ba27-914f4fe3f58c" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_cdb39596-d461-4d15-b2dc-421832ade63f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_64252996-7f69-4d4a-a8b8-31bba909d8f3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_1933db73-e018-4e64-ba27-914f4fe3f58c" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_64252996-7f69-4d4a-a8b8-31bba909d8f3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_dfc2ff9c-71a2-45d4-8819-24de1b7fd08f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_1933db73-e018-4e64-ba27-914f4fe3f58c" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_dfc2ff9c-71a2-45d4-8819-24de1b7fd08f" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/CommitmentsContingenciesandGuaranteesDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#CommitmentsContingenciesandGuaranteesDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/CommitmentsContingenciesandGuaranteesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainContingenciesLineItems_bdedfbc7-51d6-4322-a599-2c0cb6e80620" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GainContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainContingenciesTable_8a155350-2ba9-47ac-8935-4271a85286b9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GainContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GainContingenciesLineItems_bdedfbc7-51d6-4322-a599-2c0cb6e80620" xlink:to="loc_us-gaap_GainContingenciesTable_8a155350-2ba9-47ac-8935-4271a85286b9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_0b83b5c8-3fb5-4f5c-bc4a-7fb7bd6ed513" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_GainContingenciesTable_8a155350-2ba9-47ac-8935-4271a85286b9" xlink:to="loc_srt_OwnershipAxis_0b83b5c8-3fb5-4f5c-bc4a-7fb7bd6ed513" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_0b83b5c8-3fb5-4f5c-bc4a-7fb7bd6ed513_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_0b83b5c8-3fb5-4f5c-bc4a-7fb7bd6ed513" xlink:to="loc_srt_OwnershipDomain_0b83b5c8-3fb5-4f5c-bc4a-7fb7bd6ed513_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_29e17ea4-f61c-4902-b194-6dec19d2a177" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_0b83b5c8-3fb5-4f5c-bc4a-7fb7bd6ed513" xlink:to="loc_srt_OwnershipDomain_29e17ea4-f61c-4902-b194-6dec19d2a177" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_NLNHoldingsLLCMember_f96fe4b5-4f69-470a-b592-4251ff790d86" xlink:href="virt-20240930.xsd#virt_NLNHoldingsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_29e17ea4-f61c-4902-b194-6dec19d2a177" xlink:to="loc_virt_NLNHoldingsLLCMember_f96fe4b5-4f69-470a-b592-4251ff790d86" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_9a8a2773-d5af-47e3-acee-8096361afd0c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_GainContingenciesTable_8a155350-2ba9-47ac-8935-4271a85286b9" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_9a8a2773-d5af-47e3-acee-8096361afd0c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_9a8a2773-d5af-47e3-acee-8096361afd0c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_9a8a2773-d5af-47e3-acee-8096361afd0c" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_9a8a2773-d5af-47e3-acee-8096361afd0c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_e2e84c96-cf67-4f5b-b575-6b22d0ea109c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_9a8a2773-d5af-47e3-acee-8096361afd0c" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_e2e84c96-cf67-4f5b-b575-6b22d0ea109c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_8897d7df-8d7e-485b-87bd-e061a7356c63" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_e2e84c96-cf67-4f5b-b575-6b22d0ea109c" xlink:to="loc_us-gaap_SubsequentEventMember_8897d7df-8d7e-485b-87bd-e061a7356c63" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_b103a0b2-7f29-4802-bd41-dff7e4f442a0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MinorityInterestOwnershipPercentageByParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainContingenciesLineItems_bdedfbc7-51d6-4322-a599-2c0cb6e80620" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_b103a0b2-7f29-4802-bd41-dff7e4f442a0" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/CapitalStructureAdditionalInformationDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#CapitalStructureAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/CapitalStructureAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_5cd35412-3751-42bc-903e-d5f0dc6eaa80" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_374ebe1b-2c14-4c9e-b3df-dfba6bf6a7c7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_5cd35412-3751-42bc-903e-d5f0dc6eaa80" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_374ebe1b-2c14-4c9e-b3df-dfba6bf6a7c7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_fa778abd-dcf7-4636-a2f3-2f014b390941" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_374ebe1b-2c14-4c9e-b3df-dfba6bf6a7c7" xlink:to="loc_us-gaap_StatementClassOfStockAxis_fa778abd-dcf7-4636-a2f3-2f014b390941" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_fa778abd-dcf7-4636-a2f3-2f014b390941_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_fa778abd-dcf7-4636-a2f3-2f014b390941" xlink:to="loc_us-gaap_ClassOfStockDomain_fa778abd-dcf7-4636-a2f3-2f014b390941_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_851888de-29ab-4e08-b64d-516f81332bc1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_fa778abd-dcf7-4636-a2f3-2f014b390941" xlink:to="loc_us-gaap_ClassOfStockDomain_851888de-29ab-4e08-b64d-516f81332bc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_CommonClassAAndCMember_724f2cb9-3c0c-4ff0-a031-3bf5f16edd63" xlink:href="virt-20240930.xsd#virt_CommonClassAAndCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_851888de-29ab-4e08-b64d-516f81332bc1" xlink:to="loc_virt_CommonClassAAndCMember_724f2cb9-3c0c-4ff0-a031-3bf5f16edd63" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_CommonClassBAndDMember_0fdb3b89-d970-4731-a84f-8bab28057ecd" xlink:href="virt-20240930.xsd#virt_CommonClassBAndDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_851888de-29ab-4e08-b64d-516f81332bc1" xlink:to="loc_virt_CommonClassBAndDMember_0fdb3b89-d970-4731-a84f-8bab28057ecd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ClassCCommonStockAndClassDCommonStockMember_dbd2ea49-b0f4-44ca-8d82-914602573a0d" xlink:href="virt-20240930.xsd#virt_ClassCCommonStockAndClassDCommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_851888de-29ab-4e08-b64d-516f81332bc1" xlink:to="loc_virt_ClassCCommonStockAndClassDCommonStockMember_dbd2ea49-b0f4-44ca-8d82-914602573a0d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_bb2bb7cb-ecb4-47e7-9473-174e52d146bb" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_374ebe1b-2c14-4c9e-b3df-dfba6bf6a7c7" xlink:to="loc_srt_TitleOfIndividualAxis_bb2bb7cb-ecb4-47e7-9473-174e52d146bb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_bb2bb7cb-ecb4-47e7-9473-174e52d146bb_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_bb2bb7cb-ecb4-47e7-9473-174e52d146bb" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_bb2bb7cb-ecb4-47e7-9473-174e52d146bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_5247ec20-f04c-488a-9752-616f6c864b6b" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_bb2bb7cb-ecb4-47e7-9473-174e52d146bb" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_5247ec20-f04c-488a-9752-616f6c864b6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_FounderMember_d3d9188a-4671-4c65-a59f-0c198362db21" xlink:href="virt-20240930.xsd#virt_FounderMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_5247ec20-f04c-488a-9752-616f6c864b6b" xlink:to="loc_virt_FounderMember_d3d9188a-4671-4c65-a59f-0c198362db21" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_89ca92d0-eab0-465f-b6cf-8be40b711543" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_374ebe1b-2c14-4c9e-b3df-dfba6bf6a7c7" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_89ca92d0-eab0-465f-b6cf-8be40b711543" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_89ca92d0-eab0-465f-b6cf-8be40b711543_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_89ca92d0-eab0-465f-b6cf-8be40b711543" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_89ca92d0-eab0-465f-b6cf-8be40b711543_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_3df6887d-d0b7-4686-9e02-fb3eb26f3286" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_89ca92d0-eab0-465f-b6cf-8be40b711543" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_3df6887d-d0b7-4686-9e02-fb3eb26f3286" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuFinancialLlcMember_52d24cb0-80a0-4de7-94f8-62bb6e2bd78e" xlink:href="virt-20240930.xsd#virt_VirtuFinancialLlcMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_3df6887d-d0b7-4686-9e02-fb3eb26f3286" xlink:to="loc_virt_VirtuFinancialLlcMember_52d24cb0-80a0-4de7-94f8-62bb6e2bd78e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_NumberOfClassesOfCommonStock_23fbf8b4-a299-4bc3-b45c-346560db5ae4" xlink:href="virt-20240930.xsd#virt_NumberOfClassesOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_5cd35412-3751-42bc-903e-d5f0dc6eaa80" xlink:to="loc_virt_NumberOfClassesOfCommonStock_23fbf8b4-a299-4bc3-b45c-346560db5ae4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_NumberOfVotesToStockholders_d243bce9-0256-48f5-9db3-1a43a861b5de" xlink:href="virt-20240930.xsd#virt_NumberOfVotesToStockholders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_5cd35412-3751-42bc-903e-d5f0dc6eaa80" xlink:to="loc_virt_NumberOfVotesToStockholders_d243bce9-0256-48f5-9db3-1a43a861b5de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_034c0ca1-ce0f-4397-abc6-f4295674c221" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_5cd35412-3751-42bc-903e-d5f0dc6eaa80" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_034c0ca1-ce0f-4397-abc6-f4295674c221" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_NonvotingCommonInterestUnitsOutstanding_699725d9-8758-403e-bc78-bd5169b90997" xlink:href="virt-20240930.xsd#virt_NonvotingCommonInterestUnitsOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_5cd35412-3751-42bc-903e-d5f0dc6eaa80" xlink:to="loc_virt_NonvotingCommonInterestUnitsOutstanding_699725d9-8758-403e-bc78-bd5169b90997" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_NonvotingCommonInterestUnitsForfeitedOrRepurchased_4ade06df-91df-439f-b512-e85f54281fdd" xlink:href="virt-20240930.xsd#virt_NonvotingCommonInterestUnitsForfeitedOrRepurchased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_5cd35412-3751-42bc-903e-d5f0dc6eaa80" xlink:to="loc_virt_NonvotingCommonInterestUnitsForfeitedOrRepurchased_4ade06df-91df-439f-b512-e85f54281fdd" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/CapitalStructureAmendedandRestated2015ManagementIncentivePlanDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#CapitalStructureAmendedandRestated2015ManagementIncentivePlanDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/CapitalStructureAmendedandRestated2015ManagementIncentivePlanDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_9335a582-6818-4199-9674-52c2ec361628" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_0d811605-e0ab-49e9-825d-72c77e9c314c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_9335a582-6818-4199-9674-52c2ec361628" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_0d811605-e0ab-49e9-825d-72c77e9c314c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_6a5c3c75-d7f6-46b1-b926-728c5eb7da16" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_0d811605-e0ab-49e9-825d-72c77e9c314c" xlink:to="loc_us-gaap_PlanNameAxis_6a5c3c75-d7f6-46b1-b926-728c5eb7da16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_6a5c3c75-d7f6-46b1-b926-728c5eb7da16_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_6a5c3c75-d7f6-46b1-b926-728c5eb7da16" xlink:to="loc_us-gaap_PlanNameDomain_6a5c3c75-d7f6-46b1-b926-728c5eb7da16_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_ecdf8c17-e8e5-4162-86d8-ea53047bb552" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_6a5c3c75-d7f6-46b1-b926-728c5eb7da16" xlink:to="loc_us-gaap_PlanNameDomain_ecdf8c17-e8e5-4162-86d8-ea53047bb552" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ManagementIncentivePlan2015Member_d89c1290-9bdb-4105-9354-f228f8e86f3b" xlink:href="virt-20240930.xsd#virt_ManagementIncentivePlan2015Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_ecdf8c17-e8e5-4162-86d8-ea53047bb552" xlink:to="loc_virt_ManagementIncentivePlan2015Member_d89c1290-9bdb-4105-9354-f228f8e86f3b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_00043642-2aec-41bb-a5a3-e0612b8075df" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_0d811605-e0ab-49e9-825d-72c77e9c314c" xlink:to="loc_us-gaap_StatementClassOfStockAxis_00043642-2aec-41bb-a5a3-e0612b8075df" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_00043642-2aec-41bb-a5a3-e0612b8075df_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_00043642-2aec-41bb-a5a3-e0612b8075df" xlink:to="loc_us-gaap_ClassOfStockDomain_00043642-2aec-41bb-a5a3-e0612b8075df_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_1a3b0b51-1589-4a1e-9880-e3523476b0bb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_00043642-2aec-41bb-a5a3-e0612b8075df" xlink:to="loc_us-gaap_ClassOfStockDomain_1a3b0b51-1589-4a1e-9880-e3523476b0bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_cdc68980-ef5d-422c-9b71-8422e46ddc52" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_1a3b0b51-1589-4a1e-9880-e3523476b0bb" xlink:to="loc_us-gaap_CommonClassAMember_cdc68980-ef5d-422c-9b71-8422e46ddc52" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_a9b01562-1368-400a-8970-f89c0dafb996" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_9335a582-6818-4199-9674-52c2ec361628" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_a9b01562-1368-400a-8970-f89c0dafb996" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_41404213-8baf-4842-aa54-95122e2e57db" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_9335a582-6818-4199-9674-52c2ec361628" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_41404213-8baf-4842-aa54-95122e2e57db" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/CapitalStructureShareRepurchaseProgramDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#CapitalStructureShareRepurchaseProgramDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/CapitalStructureShareRepurchaseProgramDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_efb9be98-20d3-44d9-9828-94e218737d69" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_21b0cc1b-f46b-42c0-9f78-51f989032d21" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_efb9be98-20d3-44d9-9828-94e218737d69" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_21b0cc1b-f46b-42c0-9f78-51f989032d21" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_94812251-c5c3-42d3-9975-e6d477a42f12" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_21b0cc1b-f46b-42c0-9f78-51f989032d21" xlink:to="loc_us-gaap_StatementClassOfStockAxis_94812251-c5c3-42d3-9975-e6d477a42f12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_94812251-c5c3-42d3-9975-e6d477a42f12_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_94812251-c5c3-42d3-9975-e6d477a42f12" xlink:to="loc_us-gaap_ClassOfStockDomain_94812251-c5c3-42d3-9975-e6d477a42f12_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_657b626b-347a-4ce8-9bd1-381e3b18d9d6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_94812251-c5c3-42d3-9975-e6d477a42f12" xlink:to="loc_us-gaap_ClassOfStockDomain_657b626b-347a-4ce8-9bd1-381e3b18d9d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_a05bde61-04f2-491b-88fd-cf8d99aa1899" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_657b626b-347a-4ce8-9bd1-381e3b18d9d6" xlink:to="loc_us-gaap_CommonClassAMember_a05bde61-04f2-491b-88fd-cf8d99aa1899" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_510d9bb3-6618-4720-82ed-fa331aedc44a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_efb9be98-20d3-44d9-9828-94e218737d69" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_510d9bb3-6618-4720-82ed-fa331aedc44a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_StockRepurchaseProgramAdditionalAuthorizedAmount_eacbf345-e6d9-46b4-8ff7-583fb42ca795" xlink:href="virt-20240930.xsd#virt_StockRepurchaseProgramAdditionalAuthorizedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_efb9be98-20d3-44d9-9828-94e218737d69" xlink:to="loc_virt_StockRepurchaseProgramAdditionalAuthorizedAmount_eacbf345-e6d9-46b4-8ff7-583fb42ca795" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_de41e9f7-4088-44e2-88bc-5afcbccfcb9d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_efb9be98-20d3-44d9-9828-94e218737d69" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_de41e9f7-4088-44e2-88bc-5afcbccfcb9d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_9a2282fd-8f9d-4048-a86c-80a17c434148" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_efb9be98-20d3-44d9-9828-94e218737d69" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_9a2282fd-8f9d-4048-a86c-80a17c434148" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_ab453da9-a146-4b61-bec3-ed53a07fdc92" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_efb9be98-20d3-44d9-9828-94e218737d69" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_ab453da9-a146-4b61-bec3-ed53a07fdc92" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/CapitalStructureEmployeeExchangesDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#CapitalStructureEmployeeExchangesDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/CapitalStructureEmployeeExchangesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_6393c8d3-a9ad-4d4c-ab84-d066d4b83ab5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_bb27d92d-847f-4f71-b393-0a5c85e16d49" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_6393c8d3-a9ad-4d4c-ab84-d066d4b83ab5" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_bb27d92d-847f-4f71-b393-0a5c85e16d49" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_53425fea-8e0e-4e0c-ab83-df367b24254d" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_bb27d92d-847f-4f71-b393-0a5c85e16d49" xlink:to="loc_dei_LegalEntityAxis_53425fea-8e0e-4e0c-ab83-df367b24254d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_53425fea-8e0e-4e0c-ab83-df367b24254d_default" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_53425fea-8e0e-4e0c-ab83-df367b24254d" xlink:to="loc_dei_EntityDomain_53425fea-8e0e-4e0c-ab83-df367b24254d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_0b7d2685-d8b2-4428-a7ed-063645b7f1c9" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_53425fea-8e0e-4e0c-ab83-df367b24254d" xlink:to="loc_dei_EntityDomain_0b7d2685-d8b2-4428-a7ed-063645b7f1c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VFHParentLLCMember_c1edafaf-65b1-4cf2-a663-24be83f6874a" xlink:href="virt-20240930.xsd#virt_VFHParentLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_0b7d2685-d8b2-4428-a7ed-063645b7f1c9" xlink:to="loc_virt_VFHParentLLCMember_c1edafaf-65b1-4cf2-a663-24be83f6874a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_f74a8f06-6cff-407f-bfda-9dc682aaf52f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_bb27d92d-847f-4f71-b393-0a5c85e16d49" xlink:to="loc_us-gaap_StatementClassOfStockAxis_f74a8f06-6cff-407f-bfda-9dc682aaf52f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_f74a8f06-6cff-407f-bfda-9dc682aaf52f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_f74a8f06-6cff-407f-bfda-9dc682aaf52f" xlink:to="loc_us-gaap_ClassOfStockDomain_f74a8f06-6cff-407f-bfda-9dc682aaf52f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_27f815db-e08d-4a16-a788-f40dc413db2f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_f74a8f06-6cff-407f-bfda-9dc682aaf52f" xlink:to="loc_us-gaap_ClassOfStockDomain_27f815db-e08d-4a16-a788-f40dc413db2f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_6e41cbf2-2d74-469a-9d02-c3d00bdb0b27" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_27f815db-e08d-4a16-a788-f40dc413db2f" xlink:to="loc_us-gaap_CommonClassAMember_6e41cbf2-2d74-469a-9d02-c3d00bdb0b27" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_StockIssuedDuringPeriodSharesEmployeeExchanges_0f96fdaf-03bb-4b24-b95c-6a2a5f482ba9" xlink:href="virt-20240930.xsd#virt_StockIssuedDuringPeriodSharesEmployeeExchanges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_6393c8d3-a9ad-4d4c-ab84-d066d4b83ab5" xlink:to="loc_virt_StockIssuedDuringPeriodSharesEmployeeExchanges_0f96fdaf-03bb-4b24-b95c-6a2a5f482ba9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_CommonStockExchangeRatio_937204a7-5b20-4a41-8009-ad77e96a83b5" xlink:href="virt-20240930.xsd#virt_CommonStockExchangeRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_6393c8d3-a9ad-4d4c-ab84-d066d4b83ab5" xlink:to="loc_virt_CommonStockExchangeRatio_937204a7-5b20-4a41-8009-ad77e96a83b5" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/CapitalStructureScheduleofAccumulatedOtherComprehensiveIncomeDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#CapitalStructureScheduleofAccumulatedOtherComprehensiveIncomeDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/CapitalStructureScheduleofAccumulatedOtherComprehensiveIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_f62773a1-c182-42ea-9827-7b856ea42f53" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_c7d927f0-1a72-4ad3-8a88-2bc6a0e528d9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_f62773a1-c182-42ea-9827-7b856ea42f53" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_c7d927f0-1a72-4ad3-8a88-2bc6a0e528d9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_32fac7e3-a848-42e1-8152-fc811b69a364" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_c7d927f0-1a72-4ad3-8a88-2bc6a0e528d9" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_32fac7e3-a848-42e1-8152-fc811b69a364" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_32fac7e3-a848-42e1-8152-fc811b69a364_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_32fac7e3-a848-42e1-8152-fc811b69a364" xlink:to="loc_us-gaap_EquityComponentDomain_32fac7e3-a848-42e1-8152-fc811b69a364_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_8ef0bcff-a44f-4a5b-827b-8f2dc5568cd5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_32fac7e3-a848-42e1-8152-fc811b69a364" xlink:to="loc_us-gaap_EquityComponentDomain_8ef0bcff-a44f-4a5b-827b-8f2dc5568cd5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_e8d85295-2b3b-4c0c-9dd9-3d3577c78c37" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_8ef0bcff-a44f-4a5b-827b-8f2dc5568cd5" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_e8d85295-2b3b-4c0c-9dd9-3d3577c78c37" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_68942280-68fd-4fd6-a2a9-b6b3670b3dac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_e8d85295-2b3b-4c0c-9dd9-3d3577c78c37" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_68942280-68fd-4fd6-a2a9-b6b3670b3dac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_346a58fa-685c-43d6-a85b-d3d874306555" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_e8d85295-2b3b-4c0c-9dd9-3d3577c78c37" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_346a58fa-685c-43d6-a85b-d3d874306555" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_082b80e3-55e3-4611-80a0-21ebdc567f36" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_f62773a1-c182-42ea-9827-7b856ea42f53" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_082b80e3-55e3-4611-80a0-21ebdc567f36" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_2a9e2857-0c56-4042-b8a9-0186e0ad0835" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_082b80e3-55e3-4611-80a0-21ebdc567f36" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_2a9e2857-0c56-4042-b8a9-0186e0ad0835" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_ec81660e-4467-443d-8b84-891ad7e278c4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_082b80e3-55e3-4611-80a0-21ebdc567f36" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_ec81660e-4467-443d-8b84-891ad7e278c4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_1f0010f4-05f4-46f8-bce9-c0623253c753" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_082b80e3-55e3-4611-80a0-21ebdc567f36" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_1f0010f4-05f4-46f8-bce9-c0623253c753" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_ac2060f9-2224-4791-9283-5a4502d7dd02" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths_95922766-e373-4edd-a5ff-bf9594a3145c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_f62773a1-c182-42ea-9827-7b856ea42f53" xlink:to="loc_us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths_95922766-e373-4edd-a5ff-bf9594a3145c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/SharebasedCompensationNarrativeDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#SharebasedCompensationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/SharebasedCompensationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7627cbf5-7c0f-4cb9-9e4a-6c429411e092" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d44c692a-19ec-406e-95cb-303ab98cd716" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7627cbf5-7c0f-4cb9-9e4a-6c429411e092" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d44c692a-19ec-406e-95cb-303ab98cd716" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_dcf33c2a-9e4d-4e60-ad7b-3e9371b73630" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d44c692a-19ec-406e-95cb-303ab98cd716" xlink:to="loc_us-gaap_PlanNameAxis_dcf33c2a-9e4d-4e60-ad7b-3e9371b73630" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_dcf33c2a-9e4d-4e60-ad7b-3e9371b73630_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_dcf33c2a-9e4d-4e60-ad7b-3e9371b73630" xlink:to="loc_us-gaap_PlanNameDomain_dcf33c2a-9e4d-4e60-ad7b-3e9371b73630_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_efc5a0c9-4f54-42f7-9408-d00d794a698f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_dcf33c2a-9e4d-4e60-ad7b-3e9371b73630" xlink:to="loc_us-gaap_PlanNameDomain_efc5a0c9-4f54-42f7-9408-d00d794a698f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ManagementIncentivePlan2015Member_1baa8daa-ec5e-4de1-a23d-453b6472a7b2" xlink:href="virt-20240930.xsd#virt_ManagementIncentivePlan2015Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_efc5a0c9-4f54-42f7-9408-d00d794a698f" xlink:to="loc_virt_ManagementIncentivePlan2015Member_1baa8daa-ec5e-4de1-a23d-453b6472a7b2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_8c1e3825-b9d0-4d04-8ab5-ba6cc86ac141" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d44c692a-19ec-406e-95cb-303ab98cd716" xlink:to="loc_us-gaap_AwardTypeAxis_8c1e3825-b9d0-4d04-8ab5-ba6cc86ac141" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8c1e3825-b9d0-4d04-8ab5-ba6cc86ac141_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_8c1e3825-b9d0-4d04-8ab5-ba6cc86ac141" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8c1e3825-b9d0-4d04-8ab5-ba6cc86ac141_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bbe65659-b499-4ca4-a48e-b4c0cd522349" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_8c1e3825-b9d0-4d04-8ab5-ba6cc86ac141" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bbe65659-b499-4ca4-a48e-b4c0cd522349" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_8a741f7c-b56f-458d-ab51-203c5fdf4f45" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bbe65659-b499-4ca4-a48e-b4c0cd522349" xlink:to="loc_us-gaap_EmployeeStockOptionMember_8a741f7c-b56f-458d-ab51-203c5fdf4f45" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RestrictedStockUnitsAndRestrictedStockAwardsMember_31fa2137-196f-40f1-a1b6-502f2cc03be1" xlink:href="virt-20240930.xsd#virt_RestrictedStockUnitsAndRestrictedStockAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bbe65659-b499-4ca4-a48e-b4c0cd522349" xlink:to="loc_virt_RestrictedStockUnitsAndRestrictedStockAwardsMember_31fa2137-196f-40f1-a1b6-502f2cc03be1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_8cede8e2-5001-4bb0-8079-27c636ae3e9f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bbe65659-b499-4ca4-a48e-b4c0cd522349" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_8cede8e2-5001-4bb0-8079-27c636ae3e9f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_6867b8d9-2cc8-4b01-bd62-09a769ed7f09" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d44c692a-19ec-406e-95cb-303ab98cd716" xlink:to="loc_srt_RangeAxis_6867b8d9-2cc8-4b01-bd62-09a769ed7f09" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_6867b8d9-2cc8-4b01-bd62-09a769ed7f09_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_6867b8d9-2cc8-4b01-bd62-09a769ed7f09" xlink:to="loc_srt_RangeMember_6867b8d9-2cc8-4b01-bd62-09a769ed7f09_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_7cf615e2-99f0-45c7-b2ac-a1f18451ae9a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_6867b8d9-2cc8-4b01-bd62-09a769ed7f09" xlink:to="loc_srt_RangeMember_7cf615e2-99f0-45c7-b2ac-a1f18451ae9a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_c739adb6-2aac-4d5e-8e4b-61ef9c162d8d" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7cf615e2-99f0-45c7-b2ac-a1f18451ae9a" xlink:to="loc_srt_MaximumMember_c739adb6-2aac-4d5e-8e4b-61ef9c162d8d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_b8ffa4c7-9063-4b06-9d2c-a25ddfcafaa4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d44c692a-19ec-406e-95cb-303ab98cd716" xlink:to="loc_us-gaap_StatementClassOfStockAxis_b8ffa4c7-9063-4b06-9d2c-a25ddfcafaa4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_b8ffa4c7-9063-4b06-9d2c-a25ddfcafaa4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_b8ffa4c7-9063-4b06-9d2c-a25ddfcafaa4" xlink:to="loc_us-gaap_ClassOfStockDomain_b8ffa4c7-9063-4b06-9d2c-a25ddfcafaa4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_e3dd4211-4b48-4938-8e13-f3e49cf0a9e4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_b8ffa4c7-9063-4b06-9d2c-a25ddfcafaa4" xlink:to="loc_us-gaap_ClassOfStockDomain_e3dd4211-4b48-4938-8e13-f3e49cf0a9e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_ce38d44b-1611-493e-9e60-9c18b9cc1ca1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_e3dd4211-4b48-4938-8e13-f3e49cf0a9e4" xlink:to="loc_us-gaap_CommonClassAMember_ce38d44b-1611-493e-9e60-9c18b9cc1ca1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_017e3b5d-71cc-47a9-8d71-0ce67f5ab603" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7627cbf5-7c0f-4cb9-9e4a-6c429411e092" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_017e3b5d-71cc-47a9-8d71-0ce67f5ab603" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_78ad68cb-8017-4d15-9533-6d7c6836654d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7627cbf5-7c0f-4cb9-9e4a-6c429411e092" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_78ad68cb-8017-4d15-9533-6d7c6836654d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_2e7e9b19-2c5d-4497-a488-a07e4a4cee0c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7627cbf5-7c0f-4cb9-9e4a-6c429411e092" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_2e7e9b19-2c5d-4497-a488-a07e4a4cee0c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_IncreaseDecreaseInAccruedEmployeeCompensationExpense_7ea83120-fd3c-4962-adbe-7a683b1c61ed" xlink:href="virt-20240930.xsd#virt_IncreaseDecreaseInAccruedEmployeeCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7627cbf5-7c0f-4cb9-9e4a-6c429411e092" xlink:to="loc_virt_IncreaseDecreaseInAccruedEmployeeCompensationExpense_7ea83120-fd3c-4962-adbe-7a683b1c61ed" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_f527f9c1-ad75-4595-849c-c07685c439c5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7627cbf5-7c0f-4cb9-9e4a-6c429411e092" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_f527f9c1-ad75-4595-849c-c07685c439c5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_e2108b11-d22e-407a-b363-c2e7b0c058a1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7627cbf5-7c0f-4cb9-9e4a-6c429411e092" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_e2108b11-d22e-407a-b363-c2e7b0c058a1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_ef78b55e-b6b9-49b1-93de-cfa9b82ca0e2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7627cbf5-7c0f-4cb9-9e4a-6c429411e092" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_ef78b55e-b6b9-49b1-93de-cfa9b82ca0e2" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/SharebasedCompensationSummaryofActivityinOptionsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#SharebasedCompensationSummaryofActivityinOptionsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/SharebasedCompensationSummaryofActivityinOptionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_563e62cc-a37d-4c9a-b58c-cf58ca1f20dd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a574d4aa-2d23-4461-aa0e-14620007400e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_563e62cc-a37d-4c9a-b58c-cf58ca1f20dd" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a574d4aa-2d23-4461-aa0e-14620007400e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_338d29ad-095c-4e4e-a6d5-62b97b4bdc95" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a574d4aa-2d23-4461-aa0e-14620007400e" xlink:to="loc_us-gaap_PlanNameAxis_338d29ad-095c-4e4e-a6d5-62b97b4bdc95" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_338d29ad-095c-4e4e-a6d5-62b97b4bdc95_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_338d29ad-095c-4e4e-a6d5-62b97b4bdc95" xlink:to="loc_us-gaap_PlanNameDomain_338d29ad-095c-4e4e-a6d5-62b97b4bdc95_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_eb7461f6-4bd2-4fa1-8e8c-3836fe092de0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_338d29ad-095c-4e4e-a6d5-62b97b4bdc95" xlink:to="loc_us-gaap_PlanNameDomain_eb7461f6-4bd2-4fa1-8e8c-3836fe092de0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ManagementIncentivePlan2015Member_ac009afd-d341-4eb1-b73e-9924bc48c206" xlink:href="virt-20240930.xsd#virt_ManagementIncentivePlan2015Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_eb7461f6-4bd2-4fa1-8e8c-3836fe092de0" xlink:to="loc_virt_ManagementIncentivePlan2015Member_ac009afd-d341-4eb1-b73e-9924bc48c206" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_74e314af-1d8e-4162-aca2-0b5853950a85" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_563e62cc-a37d-4c9a-b58c-cf58ca1f20dd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_74e314af-1d8e-4162-aca2-0b5853950a85" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_1593ae6e-37ef-43a2-a626-19642f2f5414" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_74e314af-1d8e-4162-aca2-0b5853950a85" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_1593ae6e-37ef-43a2-a626-19642f2f5414" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_22ad9e30-dbd6-4bde-96fc-8dc10e184624" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_74e314af-1d8e-4162-aca2-0b5853950a85" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_22ad9e30-dbd6-4bde-96fc-8dc10e184624" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_1508d3f4-03dd-46e1-8218-38d05d7fda83" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_74e314af-1d8e-4162-aca2-0b5853950a85" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_1508d3f4-03dd-46e1-8218-38d05d7fda83" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_9e9b8c4f-a811-4aa9-be3c-44b5b04d2369" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_74e314af-1d8e-4162-aca2-0b5853950a85" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_9e9b8c4f-a811-4aa9-be3c-44b5b04d2369" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_c7fb3d26-3023-4df0-8bde-7921f2f898fd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_78c906ea-810e-432b-85ce-56918cfc6f67" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_563e62cc-a37d-4c9a-b58c-cf58ca1f20dd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_78c906ea-810e-432b-85ce-56918cfc6f67" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_480cf0ac-6091-4db3-971d-3486e5812483" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_78c906ea-810e-432b-85ce-56918cfc6f67" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_480cf0ac-6091-4db3-971d-3486e5812483" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_0fc50231-9fcd-466c-b65e-d0958b878e33" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_78c906ea-810e-432b-85ce-56918cfc6f67" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_0fc50231-9fcd-466c-b65e-d0958b878e33" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_a729744d-619d-42ae-8fa0-fc5eb1ca8934" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_78c906ea-810e-432b-85ce-56918cfc6f67" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_a729744d-619d-42ae-8fa0-fc5eb1ca8934" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_09121ae1-2db6-44e8-ac9c-897cf0b3be1c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_78c906ea-810e-432b-85ce-56918cfc6f67" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_09121ae1-2db6-44e8-ac9c-897cf0b3be1c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_f6f9563b-29d3-4ada-bb31-c24639c2c905" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_0b88643b-2924-4366-a92e-99a98bac210d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_563e62cc-a37d-4c9a-b58c-cf58ca1f20dd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_0b88643b-2924-4366-a92e-99a98bac210d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_857988e0-e4f9-429c-ab53-225a02ee6f45" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_0b88643b-2924-4366-a92e-99a98bac210d" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_857988e0-e4f9-429c-ab53-225a02ee6f45" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_OptionsExercisableAbstract_e783818b-7ef3-4c1a-a58f-f2544fe33a03" xlink:href="virt-20240930.xsd#virt_OptionsExercisableAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_563e62cc-a37d-4c9a-b58c-cf58ca1f20dd" xlink:to="loc_virt_OptionsExercisableAbstract_e783818b-7ef3-4c1a-a58f-f2544fe33a03" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_2e4657d6-ab59-4771-9a14-ca90f4778bd1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OptionsExercisableAbstract_e783818b-7ef3-4c1a-a58f-f2544fe33a03" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_2e4657d6-ab59-4771-9a14-ca90f4778bd1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableGrantedInPeriod_222f0d5d-816d-430d-aa76-34deff1befb0" xlink:href="virt-20240930.xsd#virt_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableGrantedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OptionsExercisableAbstract_e783818b-7ef3-4c1a-a58f-f2544fe33a03" xlink:to="loc_virt_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableGrantedInPeriod_222f0d5d-816d-430d-aa76-34deff1befb0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableExercisedInPeriod_4bdeb417-26d9-4d52-854a-e7aabe5e9bec" xlink:href="virt-20240930.xsd#virt_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableExercisedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OptionsExercisableAbstract_e783818b-7ef3-4c1a-a58f-f2544fe33a03" xlink:to="loc_virt_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableExercisedInPeriod_4bdeb417-26d9-4d52-854a-e7aabe5e9bec" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsExercisableForfeituresandExpirationsinPeriod_df5ab0ee-5ec6-47ee-8dff-d4b6e5702bed" xlink:href="virt-20240930.xsd#virt_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsExercisableForfeituresandExpirationsinPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_virt_OptionsExercisableAbstract_e783818b-7ef3-4c1a-a58f-f2544fe33a03" xlink:to="loc_virt_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsExercisableForfeituresandExpirationsinPeriod_df5ab0ee-5ec6-47ee-8dff-d4b6e5702bed" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_88e6d05b-7adb-4ca3-9d8d-46a5d3a161e3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_c0ec540e-f097-4569-b245-9b62ff726aa9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_563e62cc-a37d-4c9a-b58c-cf58ca1f20dd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_c0ec540e-f097-4569-b245-9b62ff726aa9" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/SharebasedCompensationSummaryofActivityinRSUsandRSAsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#SharebasedCompensationSummaryofActivityinRSUsandRSAsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/SharebasedCompensationSummaryofActivityinRSUsandRSAsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aaaf7abb-e096-4356-873f-40636b224653" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_333221f1-fa72-4825-ad35-37b7785f6313" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aaaf7abb-e096-4356-873f-40636b224653" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_333221f1-fa72-4825-ad35-37b7785f6313" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_628906ef-1132-4d6d-83ac-281cc55ba61c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_333221f1-fa72-4825-ad35-37b7785f6313" xlink:to="loc_us-gaap_PlanNameAxis_628906ef-1132-4d6d-83ac-281cc55ba61c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_628906ef-1132-4d6d-83ac-281cc55ba61c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_628906ef-1132-4d6d-83ac-281cc55ba61c" xlink:to="loc_us-gaap_PlanNameDomain_628906ef-1132-4d6d-83ac-281cc55ba61c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_9f2c203c-356c-4978-bb70-f9f6074721e6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_628906ef-1132-4d6d-83ac-281cc55ba61c" xlink:to="loc_us-gaap_PlanNameDomain_9f2c203c-356c-4978-bb70-f9f6074721e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ManagementIncentivePlan2015Member_e8a1514a-4c3e-4983-8eaf-717ccda883fe" xlink:href="virt-20240930.xsd#virt_ManagementIncentivePlan2015Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_9f2c203c-356c-4978-bb70-f9f6074721e6" xlink:to="loc_virt_ManagementIncentivePlan2015Member_e8a1514a-4c3e-4983-8eaf-717ccda883fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_c5285138-e2ab-4c86-bcde-1e875f0727d7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_333221f1-fa72-4825-ad35-37b7785f6313" xlink:to="loc_us-gaap_AwardTypeAxis_c5285138-e2ab-4c86-bcde-1e875f0727d7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c5285138-e2ab-4c86-bcde-1e875f0727d7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_c5285138-e2ab-4c86-bcde-1e875f0727d7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c5285138-e2ab-4c86-bcde-1e875f0727d7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_065234c0-7290-40fe-a4a7-3f4d63cdbef2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_c5285138-e2ab-4c86-bcde-1e875f0727d7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_065234c0-7290-40fe-a4a7-3f4d63cdbef2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RestrictedStockUnitsAndRestrictedStockAwardsMember_219feaa6-915b-4e9c-8bde-67e195797534" xlink:href="virt-20240930.xsd#virt_RestrictedStockUnitsAndRestrictedStockAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_065234c0-7290-40fe-a4a7-3f4d63cdbef2" xlink:to="loc_virt_RestrictedStockUnitsAndRestrictedStockAwardsMember_219feaa6-915b-4e9c-8bde-67e195797534" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RestrictedStockUnitsAndRestrictedStockAwardsPerformanceBasedMember_e2f5aa65-92a3-4788-8084-92f60a2e2dcf" xlink:href="virt-20240930.xsd#virt_RestrictedStockUnitsAndRestrictedStockAwardsPerformanceBasedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_065234c0-7290-40fe-a4a7-3f4d63cdbef2" xlink:to="loc_virt_RestrictedStockUnitsAndRestrictedStockAwardsPerformanceBasedMember_e2f5aa65-92a3-4788-8084-92f60a2e2dcf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_e3483d89-cdb7-4efd-bd90-0d20bea2ad5b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aaaf7abb-e096-4356-873f-40636b224653" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_e3483d89-cdb7-4efd-bd90-0d20bea2ad5b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_1722e435-d48a-48d1-9a8c-bdb82109e10f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_e3483d89-cdb7-4efd-bd90-0d20bea2ad5b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_1722e435-d48a-48d1-9a8c-bdb82109e10f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_7beb6755-c45a-4ea8-aaed-c49da5f4bbbc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_e3483d89-cdb7-4efd-bd90-0d20bea2ad5b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_7beb6755-c45a-4ea8-aaed-c49da5f4bbbc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_d3c669c2-6f7f-4d8a-bc27-2f930ef0abd4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_e3483d89-cdb7-4efd-bd90-0d20bea2ad5b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_d3c669c2-6f7f-4d8a-bc27-2f930ef0abd4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_51336c3e-4ee7-4c4a-9b23-2b517e53c1fe" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_e3483d89-cdb7-4efd-bd90-0d20bea2ad5b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_51336c3e-4ee7-4c4a-9b23-2b517e53c1fe" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_a832ff1e-6293-4f58-9548-b3d200850e45" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_51c94b40-cad8-4c00-b047-65107ca85de9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aaaf7abb-e096-4356-873f-40636b224653" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_51c94b40-cad8-4c00-b047-65107ca85de9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_03f9a7f3-6ad1-4c81-aa66-26d69eb03b0d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_51c94b40-cad8-4c00-b047-65107ca85de9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_03f9a7f3-6ad1-4c81-aa66-26d69eb03b0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_f3307dc2-3b1e-459c-8c4b-81e89607f264" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_51c94b40-cad8-4c00-b047-65107ca85de9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_f3307dc2-3b1e-459c-8c4b-81e89607f264" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_489e49b7-4204-475c-94cd-6b03a7f23a7d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_51c94b40-cad8-4c00-b047-65107ca85de9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_489e49b7-4204-475c-94cd-6b03a7f23a7d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_047c33b4-d5b4-42ee-af2e-68d136521ce3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_51c94b40-cad8-4c00-b047-65107ca85de9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_047c33b4-d5b4-42ee-af2e-68d136521ce3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_b4f46c81-ed59-41d2-b473-1f93c9ce5874" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/RegulatoryRequirementNarrativeDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#RegulatoryRequirementNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/RegulatoryRequirementNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_c756332a-6365-4013-be4e-50fbe03b5e46" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable_67546171-ca1f-41c0-a00c-45390e8712e6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_c756332a-6365-4013-be4e-50fbe03b5e46" xlink:to="loc_us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable_67546171-ca1f-41c0-a00c-45390e8712e6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_40721ed4-df0d-464c-b289-4633b34c0ab5" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable_67546171-ca1f-41c0-a00c-45390e8712e6" xlink:to="loc_dei_LegalEntityAxis_40721ed4-df0d-464c-b289-4633b34c0ab5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_40721ed4-df0d-464c-b289-4633b34c0ab5_default" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_40721ed4-df0d-464c-b289-4633b34c0ab5" xlink:to="loc_dei_EntityDomain_40721ed4-df0d-464c-b289-4633b34c0ab5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_6780c361-3953-47cb-bbe6-3f5d6e9475e3" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_40721ed4-df0d-464c-b289-4633b34c0ab5" xlink:to="loc_dei_EntityDomain_6780c361-3953-47cb-bbe6-3f5d6e9475e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuFinancialCapitalMarketsLlcMember_63a477d8-627b-44e5-90be-08d3545a4053" xlink:href="virt-20240930.xsd#virt_VirtuFinancialCapitalMarketsLlcMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_6780c361-3953-47cb-bbe6-3f5d6e9475e3" xlink:to="loc_virt_VirtuFinancialCapitalMarketsLlcMember_63a477d8-627b-44e5-90be-08d3545a4053" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuAmericasLlcMember_11f1f540-58fc-4a2d-8b65-d5257eb78c1c" xlink:href="virt-20240930.xsd#virt_VirtuAmericasLlcMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_6780c361-3953-47cb-bbe6-3f5d6e9475e3" xlink:to="loc_virt_VirtuAmericasLlcMember_11f1f540-58fc-4a2d-8b65-d5257eb78c1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuEuropeTradingLimitedMember_8c985d60-5688-4ef9-98ac-5171f4cbd37d" xlink:href="virt-20240930.xsd#virt_VirtuEuropeTradingLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_6780c361-3953-47cb-bbe6-3f5d6e9475e3" xlink:to="loc_virt_VirtuEuropeTradingLimitedMember_8c985d60-5688-4ef9-98ac-5171f4cbd37d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuITGHongKongLimitedMember_cf56c1bc-37a8-46c3-9497-780c7c006ff2" xlink:href="virt-20240930.xsd#virt_VirtuITGHongKongLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_6780c361-3953-47cb-bbe6-3f5d6e9475e3" xlink:to="loc_virt_VirtuITGHongKongLimitedMember_cf56c1bc-37a8-46c3-9497-780c7c006ff2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumNetCapitalRequiredForEntity1_b56fb2fa-318f-4ce5-b9d2-418c707d54b8" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumNetCapitalRequiredForEntity1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_c756332a-6365-4013-be4e-50fbe03b5e46" xlink:to="loc_srt_MinimumNetCapitalRequiredForEntity1_b56fb2fa-318f-4ce5-b9d2-418c707d54b8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RequiredNetCapitalUnderExchangeAct_b83e49ce-8096-4aa8-8037-a9faaea1a0dc" xlink:href="virt-20240930.xsd#virt_RequiredNetCapitalUnderExchangeAct"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_c756332a-6365-4013-be4e-50fbe03b5e46" xlink:to="loc_virt_RequiredNetCapitalUnderExchangeAct_b83e49ce-8096-4aa8-8037-a9faaea1a0dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RequiredNetCapitalUnderExchangeActForEveryTransactionDollarVolume_ad37a682-d63c-408b-9a34-f394b4fd57e4" xlink:href="virt-20240930.xsd#virt_RequiredNetCapitalUnderExchangeActForEveryTransactionDollarVolume"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_c756332a-6365-4013-be4e-50fbe03b5e46" xlink:to="loc_virt_RequiredNetCapitalUnderExchangeActForEveryTransactionDollarVolume_ad37a682-d63c-408b-9a34-f394b4fd57e4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_PercentageOfNYSETransactionDollarVolume_76b18645-cfc8-45df-a473-5c01a32bcbda" xlink:href="virt-20240930.xsd#virt_PercentageOfNYSETransactionDollarVolume"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_c756332a-6365-4013-be4e-50fbe03b5e46" xlink:to="loc_virt_PercentageOfNYSETransactionDollarVolume_76b18645-cfc8-45df-a473-5c01a32bcbda" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashReserveDepositRequiredAndMade_92fc13cf-e429-4462-8a2f-f807fa63091f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashReserveDepositRequiredAndMade"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_c756332a-6365-4013-be4e-50fbe03b5e46" xlink:to="loc_us-gaap_CashReserveDepositRequiredAndMade_92fc13cf-e429-4462-8a2f-f807fa63091f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashSegregatedUnderOtherRegulations_a230222c-2469-493b-af74-a65e99e7afe6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashSegregatedUnderOtherRegulations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_c756332a-6365-4013-be4e-50fbe03b5e46" xlink:to="loc_us-gaap_CashSegregatedUnderOtherRegulations_a230222c-2469-493b-af74-a65e99e7afe6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignFinancialInstitutionsActualDeposits_3f372755-338e-4dd4-bbfb-173d817494b1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignFinancialInstitutionsActualDeposits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_c756332a-6365-4013-be4e-50fbe03b5e46" xlink:to="loc_us-gaap_ForeignFinancialInstitutionsActualDeposits_3f372755-338e-4dd4-bbfb-173d817494b1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignFinancialInstitutionsActualReserveAmount_2b3ba983-dfe5-42d2-b55f-e12b23c8cb69" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignFinancialInstitutionsActualReserveAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_c756332a-6365-4013-be4e-50fbe03b5e46" xlink:to="loc_us-gaap_ForeignFinancialInstitutionsActualReserveAmount_2b3ba983-dfe5-42d2-b55f-e12b23c8cb69" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/RegulatoryRequirementRegulatoryCapitalandCapitalRequirementsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#RegulatoryRequirementRegulatoryCapitalandCapitalRequirementsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/RegulatoryRequirementRegulatoryCapitalandCapitalRequirementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_324b7f41-f45b-4b9a-b8f1-53f4cb401023" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PublicUtilitiesGeneralDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_d07ee8cd-83a1-4afc-9800-75813fc3b625" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PublicUtilitiesGeneralDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_324b7f41-f45b-4b9a-b8f1-53f4cb401023" xlink:to="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_d07ee8cd-83a1-4afc-9800-75813fc3b625" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_e45ac50b-7578-4b17-9a92-abd24cbdc758" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_d07ee8cd-83a1-4afc-9800-75813fc3b625" xlink:to="loc_dei_LegalEntityAxis_e45ac50b-7578-4b17-9a92-abd24cbdc758" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_e45ac50b-7578-4b17-9a92-abd24cbdc758_default" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_e45ac50b-7578-4b17-9a92-abd24cbdc758" xlink:to="loc_dei_EntityDomain_e45ac50b-7578-4b17-9a92-abd24cbdc758_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_7153ba4b-b923-4e54-82a5-e71f2770282b" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_e45ac50b-7578-4b17-9a92-abd24cbdc758" xlink:to="loc_dei_EntityDomain_7153ba4b-b923-4e54-82a5-e71f2770282b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuAmericasLlcMember_179864b5-bb26-4680-a704-64d5aef02446" xlink:href="virt-20240930.xsd#virt_VirtuAmericasLlcMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_7153ba4b-b923-4e54-82a5-e71f2770282b" xlink:to="loc_virt_VirtuAmericasLlcMember_179864b5-bb26-4680-a704-64d5aef02446" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RFQHubAmericasLLCMember_0d779020-f896-4d2e-883d-fc8dd15ebc05" xlink:href="virt-20240930.xsd#virt_RFQHubAmericasLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_7153ba4b-b923-4e54-82a5-e71f2770282b" xlink:to="loc_virt_RFQHubAmericasLLCMember_0d779020-f896-4d2e-883d-fc8dd15ebc05" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuCanadaCorpMember_23810373-f347-4535-bc6b-3f56f7924bc8" xlink:href="virt-20240930.xsd#virt_VirtuCanadaCorpMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_7153ba4b-b923-4e54-82a5-e71f2770282b" xlink:to="loc_virt_VirtuCanadaCorpMember_23810373-f347-4535-bc6b-3f56f7924bc8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuITGCanadaCorpMember_79acf1f1-b6dd-4b79-9ef2-cd924b2f9415" xlink:href="virt-20240930.xsd#virt_VirtuITGCanadaCorpMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_7153ba4b-b923-4e54-82a5-e71f2770282b" xlink:to="loc_virt_VirtuITGCanadaCorpMember_79acf1f1-b6dd-4b79-9ef2-cd924b2f9415" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuFinancialCanadaULCMember_75487c02-5d35-4447-a966-9d96d2c424c2" xlink:href="virt-20240930.xsd#virt_VirtuFinancialCanadaULCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_7153ba4b-b923-4e54-82a5-e71f2770282b" xlink:to="loc_virt_VirtuFinancialCanadaULCMember_75487c02-5d35-4447-a966-9d96d2c424c2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuEuropeTradingLimitedMember_ef3d977c-28a9-443f-bade-0201e9c4d97a" xlink:href="virt-20240930.xsd#virt_VirtuEuropeTradingLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_7153ba4b-b923-4e54-82a5-e71f2770282b" xlink:to="loc_virt_VirtuEuropeTradingLimitedMember_ef3d977c-28a9-443f-bade-0201e9c4d97a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuFinancialIrelandLtdMember_8f0f8f95-3b5c-441f-b270-d873c0864bf2" xlink:href="virt-20240930.xsd#virt_VirtuFinancialIrelandLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_7153ba4b-b923-4e54-82a5-e71f2770282b" xlink:to="loc_virt_VirtuFinancialIrelandLtdMember_8f0f8f95-3b5c-441f-b270-d873c0864bf2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuITGUKLimitedMember_b3cad59a-8c04-479e-a50b-8f1898005a7b" xlink:href="virt-20240930.xsd#virt_VirtuITGUKLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_7153ba4b-b923-4e54-82a5-e71f2770282b" xlink:to="loc_virt_VirtuITGUKLimitedMember_b3cad59a-8c04-479e-a50b-8f1898005a7b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuITGAustraliaLimitedMember_56a759fa-6eab-4198-ad6f-25ad75dd223f" xlink:href="virt-20240930.xsd#virt_VirtuITGAustraliaLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_7153ba4b-b923-4e54-82a5-e71f2770282b" xlink:to="loc_virt_VirtuITGAustraliaLimitedMember_56a759fa-6eab-4198-ad6f-25ad75dd223f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuITGHongKongLimitedMember_5520a644-6c43-4409-bb0d-2750bb6a6e27" xlink:href="virt-20240930.xsd#virt_VirtuITGHongKongLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_7153ba4b-b923-4e54-82a5-e71f2770282b" xlink:to="loc_virt_VirtuITGHongKongLimitedMember_5520a644-6c43-4409-bb0d-2750bb6a6e27" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuITGSingaporePteLimitedMember_95856d5c-ed83-4850-8b31-5f8a8f309597" xlink:href="virt-20240930.xsd#virt_VirtuITGSingaporePteLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_7153ba4b-b923-4e54-82a5-e71f2770282b" xlink:to="loc_virt_VirtuITGSingaporePteLimitedMember_95856d5c-ed83-4850-8b31-5f8a8f309597" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_VirtuFinancialSingaporePteLtdMember_a92b7cb7-1ed4-46aa-9fa8-4f8b87d75a1e" xlink:href="virt-20240930.xsd#virt_VirtuFinancialSingaporePteLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_7153ba4b-b923-4e54-82a5-e71f2770282b" xlink:to="loc_virt_VirtuFinancialSingaporePteLtdMember_a92b7cb7-1ed4-46aa-9fa8-4f8b87d75a1e" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_f322db7f-d584-4fc3-980b-9647eafd5fa6" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresTable_d07ee8cd-83a1-4afc-9800-75813fc3b625" xlink:to="loc_srt_StatementGeographicalAxis_f322db7f-d584-4fc3-980b-9647eafd5fa6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_f322db7f-d584-4fc3-980b-9647eafd5fa6_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_f322db7f-d584-4fc3-980b-9647eafd5fa6" xlink:to="loc_srt_SegmentGeographicalDomain_f322db7f-d584-4fc3-980b-9647eafd5fa6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_8f125a73-3d6f-4039-917e-2db381e2389d" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_f322db7f-d584-4fc3-980b-9647eafd5fa6" xlink:to="loc_srt_SegmentGeographicalDomain_8f125a73-3d6f-4039-917e-2db381e2389d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CA_b5c86be6-12bf-47f1-8bf6-6b6ac7c968b1" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_8f125a73-3d6f-4039-917e-2db381e2389d" xlink:to="loc_country_CA_b5c86be6-12bf-47f1-8bf6-6b6ac7c968b1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_IE_c4b0227e-6750-4487-bcb3-a24da8a65bbe" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_IE"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_8f125a73-3d6f-4039-917e-2db381e2389d" xlink:to="loc_country_IE_c4b0227e-6750-4487-bcb3-a24da8a65bbe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_GB_7afb2533-f9fe-4ed5-b8d5-516c8bf1e97e" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_GB"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_8f125a73-3d6f-4039-917e-2db381e2389d" xlink:to="loc_country_GB_7afb2533-f9fe-4ed5-b8d5-516c8bf1e97e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AsiaPacificMember_b4fab5a0-6dd8-43db-b44b-1afd53c83555" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_AsiaPacificMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_8f125a73-3d6f-4039-917e-2db381e2389d" xlink:to="loc_srt_AsiaPacificMember_b4fab5a0-6dd8-43db-b44b-1afd53c83555" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NetCapital_cc056a5d-a6d5-4a35-be88-4be90ad29e05" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_NetCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_324b7f41-f45b-4b9a-b8f1-53f4cb401023" xlink:to="loc_srt_NetCapital_cc056a5d-a6d5-4a35-be88-4be90ad29e05" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumNetCapitalRequired1_fb94120b-1c8d-49ab-9b02-d6298fab3989" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumNetCapitalRequired1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_324b7f41-f45b-4b9a-b8f1-53f4cb401023" xlink:to="loc_srt_MinimumNetCapitalRequired1_fb94120b-1c8d-49ab-9b02-d6298fab3989" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ExcessNetCapitalAt1500Percent_e2c3458b-1c99-4289-86db-3678fa1fa0df" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ExcessNetCapitalAt1500Percent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesGeneralDisclosuresLineItems_324b7f41-f45b-4b9a-b8f1-53f4cb401023" xlink:to="loc_srt_ExcessNetCapitalAt1500Percent_e2c3458b-1c99-4289-86db-3678fa1fa0df" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/GeographicInformationandBusinessSegmentsRevenuesbyGeographicAreaDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#GeographicInformationandBusinessSegmentsRevenuesbyGeographicAreaDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/GeographicInformationandBusinessSegmentsRevenuesbyGeographicAreaDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_290cc47a-08b3-40f6-85be-50b539b800bc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_f96a50cf-309f-4896-b626-c26cb98d9a25" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_290cc47a-08b3-40f6-85be-50b539b800bc" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_f96a50cf-309f-4896-b626-c26cb98d9a25" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_07f3e471-9856-41d5-802e-9c58139d1464" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_f96a50cf-309f-4896-b626-c26cb98d9a25" xlink:to="loc_srt_StatementGeographicalAxis_07f3e471-9856-41d5-802e-9c58139d1464" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_07f3e471-9856-41d5-802e-9c58139d1464_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_07f3e471-9856-41d5-802e-9c58139d1464" xlink:to="loc_srt_SegmentGeographicalDomain_07f3e471-9856-41d5-802e-9c58139d1464_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_8d93aa82-ba68-45bb-b1e7-8500a9d5dea0" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_07f3e471-9856-41d5-802e-9c58139d1464" xlink:to="loc_srt_SegmentGeographicalDomain_8d93aa82-ba68-45bb-b1e7-8500a9d5dea0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_6f4c9118-fa27-4214-afde-e22d5f2f4f59" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_8d93aa82-ba68-45bb-b1e7-8500a9d5dea0" xlink:to="loc_country_US_6f4c9118-fa27-4214-afde-e22d5f2f4f59" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_IE_edc0c6db-5126-4a57-89d7-49f96117593b" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_IE"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_8d93aa82-ba68-45bb-b1e7-8500a9d5dea0" xlink:to="loc_country_IE_edc0c6db-5126-4a57-89d7-49f96117593b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_OtherCountriesMember_36ed5e5b-334f-471b-a33f-ce757fcac14b" xlink:href="virt-20240930.xsd#virt_OtherCountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_8d93aa82-ba68-45bb-b1e7-8500a9d5dea0" xlink:to="loc_virt_OtherCountriesMember_36ed5e5b-334f-471b-a33f-ce757fcac14b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_1e019b94-cc77-46b4-9ac5-0ad203498291" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_290cc47a-08b3-40f6-85be-50b539b800bc" xlink:to="loc_us-gaap_Revenues_1e019b94-cc77-46b4-9ac5-0ad203498291" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/GeographicInformationandBusinessSegmentsSegmentsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#GeographicInformationandBusinessSegmentsSegmentsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/GeographicInformationandBusinessSegmentsSegmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_3eaae161-4e1a-4ba2-84b0-6efc136587d4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_f88c651e-4912-4dc2-a80b-38295ec2657e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_3eaae161-4e1a-4ba2-84b0-6efc136587d4" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_f88c651e-4912-4dc2-a80b-38295ec2657e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_977bd35e-2aac-4c28-8e8c-7af536e9dd38" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_f88c651e-4912-4dc2-a80b-38295ec2657e" xlink:to="loc_srt_ConsolidationItemsAxis_977bd35e-2aac-4c28-8e8c-7af536e9dd38" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_977bd35e-2aac-4c28-8e8c-7af536e9dd38_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_977bd35e-2aac-4c28-8e8c-7af536e9dd38" xlink:to="loc_srt_ConsolidationItemsDomain_977bd35e-2aac-4c28-8e8c-7af536e9dd38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_9753e0fc-45c8-47da-a4f2-259905b4d308" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_977bd35e-2aac-4c28-8e8c-7af536e9dd38" xlink:to="loc_srt_ConsolidationItemsDomain_9753e0fc-45c8-47da-a4f2-259905b4d308" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_bda7f1ac-0f3b-42d5-bf70-f1149f92e67a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_9753e0fc-45c8-47da-a4f2-259905b4d308" xlink:to="loc_us-gaap_OperatingSegmentsMember_bda7f1ac-0f3b-42d5-bf70-f1149f92e67a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaterialReconcilingItemsMember_58b09afa-6048-4582-b3db-8218d82a0107" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MaterialReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_9753e0fc-45c8-47da-a4f2-259905b4d308" xlink:to="loc_us-gaap_MaterialReconcilingItemsMember_58b09afa-6048-4582-b3db-8218d82a0107" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_7dda1ec5-c515-40ff-bcc8-42e4959a3608" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_f88c651e-4912-4dc2-a80b-38295ec2657e" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_7dda1ec5-c515-40ff-bcc8-42e4959a3608" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_7dda1ec5-c515-40ff-bcc8-42e4959a3608_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_7dda1ec5-c515-40ff-bcc8-42e4959a3608" xlink:to="loc_us-gaap_SegmentDomain_7dda1ec5-c515-40ff-bcc8-42e4959a3608_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_1c047a7e-894c-4331-8deb-e873c5b399eb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_7dda1ec5-c515-40ff-bcc8-42e4959a3608" xlink:to="loc_us-gaap_SegmentDomain_1c047a7e-894c-4331-8deb-e873c5b399eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_MarketMakingSegmentMember_c912481e-3bfd-4126-8a3b-8ab430794470" xlink:href="virt-20240930.xsd#virt_MarketMakingSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1c047a7e-894c-4331-8deb-e873c5b399eb" xlink:to="loc_virt_MarketMakingSegmentMember_c912481e-3bfd-4126-8a3b-8ab430794470" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_ExecutionServicesSegmentMember_04ce077c-c122-45b6-a589-7b99bd8a9301" xlink:href="virt-20240930.xsd#virt_ExecutionServicesSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1c047a7e-894c-4331-8deb-e873c5b399eb" xlink:to="loc_virt_ExecutionServicesSegmentMember_04ce077c-c122-45b6-a589-7b99bd8a9301" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateMember_3c61a537-5539-46f4-9c51-7809b057fbad" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CorporateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1c047a7e-894c-4331-8deb-e873c5b399eb" xlink:to="loc_us-gaap_CorporateMember_3c61a537-5539-46f4-9c51-7809b057fbad" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_b0ac7d84-75de-4345-a07b-18fe220e9a74" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_3eaae161-4e1a-4ba2-84b0-6efc136587d4" xlink:to="loc_us-gaap_Revenues_b0ac7d84-75de-4345-a07b-18fe220e9a74" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_e62d0464-66a8-4a02-9e50-e6fb9b13339f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_3eaae161-4e1a-4ba2-84b0-6efc136587d4" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_e62d0464-66a8-4a02-9e50-e6fb9b13339f" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/RelatedPartyTransactionsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#RelatedPartyTransactionsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/RelatedPartyTransactionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_f3201625-6e4a-4092-9eeb-d3299ea6a671" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_7dabcc23-ace3-4af3-a0e3-45f45548e8f8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f3201625-6e4a-4092-9eeb-d3299ea6a671" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_7dabcc23-ace3-4af3-a0e3-45f45548e8f8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_879bec9c-85ad-4da2-abb0-a948571c7269" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_7dabcc23-ace3-4af3-a0e3-45f45548e8f8" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_879bec9c-85ad-4da2-abb0-a948571c7269" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_879bec9c-85ad-4da2-abb0-a948571c7269_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_879bec9c-85ad-4da2-abb0-a948571c7269" xlink:to="loc_us-gaap_RelatedPartyDomain_879bec9c-85ad-4da2-abb0-a948571c7269_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_cc3d6129-b909-400e-8387-4246add1bf22" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_879bec9c-85ad-4da2-abb0-a948571c7269" xlink:to="loc_us-gaap_RelatedPartyDomain_cc3d6129-b909-400e-8387-4246add1bf22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_c941c8bb-d492-48a8-8b54-3e402219a774" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_cc3d6129-b909-400e-8387-4246add1bf22" xlink:to="loc_us-gaap_RelatedPartyMember_c941c8bb-d492-48a8-8b54-3e402219a774" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_9c960449-9fd8-49e9-9100-b90048b2c24b" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_7dabcc23-ace3-4af3-a0e3-45f45548e8f8" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_9c960449-9fd8-49e9-9100-b90048b2c24b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_9c960449-9fd8-49e9-9100-b90048b2c24b_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_9c960449-9fd8-49e9-9100-b90048b2c24b" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_9c960449-9fd8-49e9-9100-b90048b2c24b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_aeee8300-9aae-4c0a-8dd1-c696b40cdcf9" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_9c960449-9fd8-49e9-9100-b90048b2c24b" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_aeee8300-9aae-4c0a-8dd1-c696b40cdcf9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_SBIJapannextMember_49b2dfdc-6887-4fdd-8a55-eebe284f55dc" xlink:href="virt-20240930.xsd#virt_SBIJapannextMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_aeee8300-9aae-4c0a-8dd1-c696b40cdcf9" xlink:to="loc_virt_SBIJapannextMember_49b2dfdc-6887-4fdd-8a55-eebe284f55dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_6b80f776-fe3f-4080-b7c6-a7d3befa52f7" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_7dabcc23-ace3-4af3-a0e3-45f45548e8f8" xlink:to="loc_srt_CounterpartyNameAxis_6b80f776-fe3f-4080-b7c6-a7d3befa52f7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_6b80f776-fe3f-4080-b7c6-a7d3befa52f7_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_6b80f776-fe3f-4080-b7c6-a7d3befa52f7" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_6b80f776-fe3f-4080-b7c6-a7d3befa52f7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_aaf58d2c-c0fd-4d5f-94cf-a277e5e3aa47" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_6b80f776-fe3f-4080-b7c6-a7d3befa52f7" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_aaf58d2c-c0fd-4d5f-94cf-a277e5e3aa47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_MicrowaveCommunicationNetworkJointVenturesMember_c62b2911-96e2-457f-89ad-3e70dbe58280" xlink:href="virt-20240930.xsd#virt_MicrowaveCommunicationNetworkJointVenturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_aaf58d2c-c0fd-4d5f-94cf-a277e5e3aa47" xlink:to="loc_virt_MicrowaveCommunicationNetworkJointVenturesMember_c62b2911-96e2-457f-89ad-3e70dbe58280" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilities_004314b4-99b3-49f7-a0a1-03b04ca6fcaf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f3201625-6e4a-4092-9eeb-d3299ea6a671" xlink:to="loc_us-gaap_OtherLiabilities_004314b4-99b3-49f7-a0a1-03b04ca6fcaf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_3e97ba5d-f1a4-4267-a1da-d27bbd0eb782" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyTransactionAmountsOfTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f3201625-6e4a-4092-9eeb-d3299ea6a671" xlink:to="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_3e97ba5d-f1a4-4267-a1da-d27bbd0eb782" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RegulatoryAndTransactionFees_477d2347-4b9e-4d09-9f09-d8da5010519e" xlink:href="virt-20240930.xsd#virt_RegulatoryAndTransactionFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f3201625-6e4a-4092-9eeb-d3299ea6a671" xlink:to="loc_virt_RegulatoryAndTransactionFees_477d2347-4b9e-4d09-9f09-d8da5010519e" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.virtu.com/role/SubsequentEventsDetails" xlink:type="simple" xlink:href="virt-20240930.xsd#SubsequentEventsDetails"/>
  <link:definitionLink xlink:role="http://www.virtu.com/role/SubsequentEventsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_0217acd5-907b-4d17-98d3-53727349d13e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_66fc5fc6-c494-453f-9b32-966cac9393e8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_0217acd5-907b-4d17-98d3-53727349d13e" xlink:to="loc_us-gaap_SubsequentEventTable_66fc5fc6-c494-453f-9b32-966cac9393e8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_a52a75a1-8361-4dee-8c1b-f89a5370d556" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_66fc5fc6-c494-453f-9b32-966cac9393e8" xlink:to="loc_us-gaap_StatementClassOfStockAxis_a52a75a1-8361-4dee-8c1b-f89a5370d556" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_a52a75a1-8361-4dee-8c1b-f89a5370d556_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_a52a75a1-8361-4dee-8c1b-f89a5370d556" xlink:to="loc_us-gaap_ClassOfStockDomain_a52a75a1-8361-4dee-8c1b-f89a5370d556_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_52ea0d80-0166-4b31-8a5c-345094102c4f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_a52a75a1-8361-4dee-8c1b-f89a5370d556" xlink:to="loc_us-gaap_ClassOfStockDomain_52ea0d80-0166-4b31-8a5c-345094102c4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_043aecad-0b7b-4277-9789-e3fd373b52cd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_52ea0d80-0166-4b31-8a5c-345094102c4f" xlink:to="loc_us-gaap_CommonClassAMember_043aecad-0b7b-4277-9789-e3fd373b52cd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_3decb49c-cfb2-4bd0-96bc-ea63a9bc5b32" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_66fc5fc6-c494-453f-9b32-966cac9393e8" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_3decb49c-cfb2-4bd0-96bc-ea63a9bc5b32" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_3decb49c-cfb2-4bd0-96bc-ea63a9bc5b32_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_3decb49c-cfb2-4bd0-96bc-ea63a9bc5b32" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_3decb49c-cfb2-4bd0-96bc-ea63a9bc5b32_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_07bb48c6-d463-4074-93e4-2e78b7033d62" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_3decb49c-cfb2-4bd0-96bc-ea63a9bc5b32" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_07bb48c6-d463-4074-93e4-2e78b7033d62" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_4866ab22-568f-4c05-b4a1-355c41ec9fa0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_07bb48c6-d463-4074-93e4-2e78b7033d62" xlink:to="loc_us-gaap_SubsequentEventMember_4866ab22-568f-4c05-b4a1-355c41ec9fa0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_ccafcc0d-cd59-4b82-9eb3-c11f000d42ac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_0217acd5-907b-4d17-98d3-53727349d13e" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_ccafcc0d-cd59-4b82-9eb3-c11f000d42ac" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd#AwardTypeOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RestrictedStockUnitsAndRestrictedStockAwardsMember_4ac8b67f-da36-4a3e-a63f-dd0f95267089" xlink:href="virt-20240930.xsd#virt_RestrictedStockUnitsAndRestrictedStockAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_virt_RestrictedStockUnitsAndRestrictedStockAwardsMember_4ac8b67f-da36-4a3e-a63f-dd0f95267089" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_RestrictedStockUnitsAndRestrictedStockAwardsPerformanceBasedMember_b5486f1b-258b-4d38-b976-3104ea36ca17" xlink:href="virt-20240930.xsd#virt_RestrictedStockUnitsAndRestrictedStockAwardsPerformanceBasedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_virt_RestrictedStockUnitsAndRestrictedStockAwardsPerformanceBasedMember_b5486f1b-258b-4d38-b976-3104ea36ca17" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="simple" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-roles-2024.xsd#eedm"/>
  <link:definitionLink xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_virt_CommissionsNetAndTechnologyServicesMember_021ae6b4-8a55-4adf-8505-dd84a1e059c0" xlink:href="virt-20240930.xsd#virt_CommissionsNetAndTechnologyServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain" xlink:to="loc_virt_CommissionsNetAndTechnologyServicesMember_021ae6b4-8a55-4adf-8505-dd84a1e059c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIncome" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract" xlink:to="loc_us-gaap_OtherIncome" xlink:type="arc" order="1"/>
  </link:definitionLink>
</link:linkbase>
