<SEC-DOCUMENT>0000798354-25-000134.txt : 20250529
<SEC-HEADER>0000798354-25-000134.hdr.sgml : 20250529
<ACCEPTANCE-DATETIME>20250529164226
ACCESSION NUMBER:		0000798354-25-000134
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20250528
FILED AS OF DATE:		20250529
DATE AS OF CHANGE:		20250529

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Gelb Andrew
		CENTRAL INDEX KEY:			0001654671
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38962
		FILM NUMBER:		251004158

	MAIL ADDRESS:	
		STREET 1:		600 N. VEL R. PHILLIPS AVENUE
		CITY:			MILWAUKEE
		STATE:			WI
		ZIP:			53203

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			FISERV INC
		CENTRAL INDEX KEY:			0000798354
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-BUSINESS SERVICES, NEC [7389]
		ORGANIZATION NAME:           	07 Trade & Services
		EIN:				391506125
		STATE OF INCORPORATION:			WI
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		600 N. VEL R. PHILLIPS AVENUE
		CITY:			MILWAUKEE
		STATE:			WI
		ZIP:			53203
		BUSINESS PHONE:		2628795000

	MAIL ADDRESS:	
		STREET 1:		600 N. VEL R. PHILLIPS AVENUE
		CITY:			MILWAUKEE
		STATE:			WI
		ZIP:			53203
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wk-form4_1748551337.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-05-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000798354</issuerCik>
        <issuerName>FISERV INC</issuerName>
        <issuerTradingSymbol>FI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001654671</rptOwnerCik>
            <rptOwnerName>Gelb Andrew</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>600 N. VEL R. PHILLIPS AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MILWAUKEE</rptOwnerCity>
            <rptOwnerState>WI</rptOwnerState>
            <rptOwnerZipCode>53203</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP, Co-Head of Fin. Sols.</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2025-05-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5652</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>160</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>25385</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">This transaction was executed in multiple trades at prices ranging from $160.00 to $160.01. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Eric C. Nelson (attorney-in-fact)</signatureName>
        <signatureDate>2025-05-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
