<SEC-DOCUMENT>0001395942-18-000055.txt : 20180302
<SEC-HEADER>0001395942-18-000055.hdr.sgml : 20180302
<ACCEPTANCE-DATETIME>20180302125651
ACCESSION NUMBER:		0001395942-18-000055
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20180228
FILED AS OF DATE:		20180302
DATE AS OF CHANGE:		20180302

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Price Lisa A.
		CENTRAL INDEX KEY:			0001580036

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34568
		FILM NUMBER:		18660862

	MAIL ADDRESS:	
		STREET 1:		13085 HAMILTON CROSSING BLVD.
		CITY:			CARMEL
		STATE:			IN
		ZIP:			46032

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			KAR Auction Services, Inc.
		CENTRAL INDEX KEY:			0001395942
		STANDARD INDUSTRIAL CLASSIFICATION:	RETAIL-AUTO DEALERS & GASOLINE STATIONS [5500]
		IRS NUMBER:				208744739
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		13085 HAMILTON CROSSING BOULEVARD
		CITY:			CARMEL
		STATE:			IN
		ZIP:			46032
		BUSINESS PHONE:		(800) 923-3725

	MAIL ADDRESS:	
		STREET 1:		13085 HAMILTON CROSSING BOULEVARD
		CITY:			CARMEL
		STATE:			IN
		ZIP:			46032

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	KAR Holdings, Inc.
		DATE OF NAME CHANGE:	20070409
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_152001339317987.xml
<DESCRIPTION>FORM 4
<TEXT>
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    <documentType>4</documentType>

    <periodOfReport>2018-02-28</periodOfReport>

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    <issuer>
        <issuerCik>0001395942</issuerCik>
        <issuerName>KAR Auction Services, Inc.</issuerName>
        <issuerTradingSymbol>KAR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001580036</rptOwnerCik>
            <rptOwnerName>Price Lisa A.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O: KAR AUCTION SERVICES, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>13085 HAMILTON CROSSING BLVD.</rptOwnerStreet2>
            <rptOwnerCity>CARMEL</rptOwnerCity>
            <rptOwnerState>IN</rptOwnerState>
            <rptOwnerZipCode>46032</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP of Human Resources</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-02-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
                    <value>2188</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>30.89</value>
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                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
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                    <value>13730.0527</value>
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                </directOrIndirectOwnership>
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        </nonDerivativeTransaction>
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    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>30.89</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2018-02-28</value>
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                <transactionPricePerShare>
                    <value>30.89</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2024-02-27</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2188.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8749</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
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        <derivativeHolding>
            <securityTitle>
                <value>Restricted Stock Units</value>
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            <conversionOrExercisePrice>
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            <expirationDate>
                <footnoteId id="F5"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>566.0</value>
                </underlyingSecurityShares>
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                <sharesOwnedFollowingTransaction>
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                <value>Restricted Stock Units</value>
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            <exerciseDate>
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            <expirationDate>
                <footnoteId id="F6"/>
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            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>864.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>864</value>
                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>D</value>
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        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Includes 1,212.6153 shares acquired (including 45.6668 shares acquired by dividend reinvestment) pursuant to the Company's Employee Stock Purchase Plan.</footnote>
        <footnote id="F2">This transaction was effected pursuant to a Rule 10b5-1 Plan adopted by the reporting person on December 15, 2017.</footnote>
        <footnote id="F3">All of these options are currently exercisable.</footnote>
        <footnote id="F4">Each restricted stock unit is convertible into a share of common stock on a 1-for-1 basis.</footnote>
        <footnote id="F5">These restricted stock units remain subject to a time-vesting requirement and are scheduled to vest and settle in common stock as follows: one-third of these restricted stock units vested on February 23, 2017, one-third of these restricted stock units vested on February 22, 2018 and the remaining one-third of these restricted stock units vest on February 22, 2019, assuming continued employment through the applicable vesting date.</footnote>
        <footnote id="F6">These restricted stock units remain subject to a time-vesting requirement and are scheduled to vest and settle in common stock as follows: one-third of these restricted stock units vested on February 24, 2018, one-third of these restricted stock units vest on February 24, 2019 and the remaining one-third of these restricted stock units vest on February 24, 2020, assuming continued employment through the applicable vesting date.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Rebecca C. Polak as Attorney In Fact</signatureName>
        <signatureDate>2018-03-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
