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

    <schemaVersion>X0607</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2026-08-03</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000746838</issuerCik>
        <issuerName>UNISYS CORP</issuerName>
        <issuerTradingSymbol>UIS</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002147441</rptOwnerCik>
            <rptOwnerName>Bundy David J.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>C/O UNISYS CORP.</rptOwnerStreet1>
            <rptOwnerStreet2>801 LAKEVIEW DRIVE, SUITE 100</rptOwnerStreet2>
            <rptOwnerCity>BLUE BELL</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19422</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP, Chief People Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>40483</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Includes 28,598 unvested restricted stock units (&quot;RSUs&quot;) held by the reporting person previously granted pursuant to long-term equity compensation plans of Unisys Corporation, which includes: (i) 2,003 unvested RSUs granted on February 26, 2024 that vest on February 26, 2027, (ii) 11,162 unvested RSUs granted on February 24, 2025 that vest in equal amounts on February 24, 2027 and February 24, 2028, and (iii) 15,433 unvested RSUs granted on February 27, 2026, of which 5,144 unvested RSUs vest on each of February 27, 2027 and 2028 and 5,145 unvested RSUs vest on February 27, 2029.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Tina V. John, Attorney-in-Fact</signatureName>
        <signatureDate>2026-08-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
