<?xml version="1.0"?>
<ownershipDocument>

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    <periodOfReport>2026-01-31</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001592386</issuerCik>
        <issuerName>Virtu Financial, Inc.</issuerName>
        <issuerTradingSymbol>VIRT</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001602472</rptOwnerCik>
            <rptOwnerName>Molluso Joseph</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O VIRTU FINANCIAL, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>1633 BROADWAY</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10019</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Co-President &amp; Co-COO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

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                <value>2026-02-02</value>
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                <transactionCode>M</transactionCode>
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        </nonDerivativeTransaction>
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    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
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            </securityTitle>
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            <transactionAmounts>
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                    <value>37500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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            <exerciseDate>
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            </exerciseDate>
            <expirationDate>
                <footnoteId id="F5"/>
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            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>37500</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                <value>2026-01-31</value>
            </transactionDate>
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                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
                    <value>37500</value>
                </transactionShares>
                <transactionPricePerShare>
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                </transactionShares>
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            <expirationDate>
                <footnoteId id="F9"/>
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            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>11193</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                <sharesOwnedFollowingTransaction>
                    <value>82873</value>
                </sharesOwnedFollowingTransaction>
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        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">37,500 RSUs were earned as a result of the Issuer's achievement of associated performance objective for 2024 and vested and settled in shares of Class A common stock on January 31, 2026. The RSUs were granted under the Issuer's Second Amended and Restated 2015 Management Incentive pursuant to the Amended and Restated Employment Agreement between the Issuer and Mr. Joseph Molluso.</footnote>
        <footnote id="F2">Shares of Class A common stock withheld for tax by the Issuer in relation to the settlement of vested RSUs in accordance with the Issuer's Second Amended and Restated 2015 Management Incentive Plan.</footnote>
        <footnote id="F3">37,500 shares of class A common stock were earned as a result of the Issuer's achievement of associated performance objective for 2025 and vested on January 31, 2026. The shares were granted under the Issuer's Second Amended and Restated 2015 Management Incentive pursuant to the Amended and Restated Employment Agreement between the Issuer and Mr. Joseph Molluso.</footnote>
        <footnote id="F4">Shares of Class A common stock issued in settlement of vested RSUs granted under the Issuer's Second Amended and Restated 2015 Management Incentive Plan.</footnote>
        <footnote id="F5">The RSUs vested January 31, 2026</footnote>
        <footnote id="F6">37,500 RSUs were earned as a result of the Issuer's achievement of associated performance objective for 2025. The RSUs were granted under the Issuer's Second Amended and Restated 2015 Management Incentive pursuant to the Amended and Restated Employment Agreement between the Issuer and Mr. Joseph Molluso.</footnote>
        <footnote id="F7">The RSUs vest January 31, 2027.</footnote>
        <footnote id="F8">Each RSU is granted under the Issuer's Amended and Restated 2015 Management Incentive Plan and represents a contingent right to receive one share of Class A common stock of the Issuer.</footnote>
        <footnote id="F9">The RSUs vested February 2, 2026.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Justin Waldie, as Attorney-in-Fact</signatureName>
        <signatureDate>2026-02-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
