<SEC-DOCUMENT>0001395942-17-000104.txt : 20170822
<SEC-HEADER>0001395942-17-000104.hdr.sgml : 20170822
<ACCEPTANCE-DATETIME>20170822163957
ACCESSION NUMBER:		0001395942-17-000104
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20170818
FILED AS OF DATE:		20170822
DATE AS OF CHANGE:		20170822

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			St. Hilaire Stephane
		CENTRAL INDEX KEY:			0001592827

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34568
		FILM NUMBER:		171045549

	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_150343438331870.xml
<DESCRIPTION>FORM 4
<TEXT>
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    <periodOfReport>2017-08-18</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001592827</rptOwnerCik>
            <rptOwnerName>St. Hilaire Stephane</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>13085 HAMILTON CROSSING BLVD.</rptOwnerStreet1>
            <rptOwnerStreet2></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>President and CEO of ADESA</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
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                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-08-18</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>20</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14506.4774</value>
                    <footnoteId id="F1"/>
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            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
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        </nonDerivativeTransaction>
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                <value>Common Stock</value>
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            <transactionDate>
                <value>2017-08-18</value>
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                <transactionFormType>4</transactionFormType>
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                    <value>20</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>44.36</value>
                </transactionPricePerShare>
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                </transactionAcquiredDisposedCode>
            </transactionAmounts>
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                <sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
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    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>10.0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-08-18</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
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                    <value>10</value>
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                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2017-08-20</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>20.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
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        </derivativeTransaction>
        <derivativeHolding>
            <securityTitle>
                <value>Employee Stock Option (right to buy)</value>
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            <conversionOrExercisePrice>
                <value>30.89</value>
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            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2024-02-27</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>38884.0</value>
                    <footnoteId id="F4"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>38884</value>
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                <directOrIndirectOwnership>
                    <value>D</value>
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        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Employee Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>13.46</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2020-03-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>72768.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>72768</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F5"/>
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            <exerciseDate>
                <footnoteId id="F6"/>
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            <expirationDate>
                <footnoteId id="F6"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1072.0</value>
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            </underlyingSecurity>
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                <sharesOwnedFollowingTransaction>
                    <value>1072</value>
                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>D</value>
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        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
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            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F5"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F7"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F7"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2309.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2309</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Includes 1,183.3136 shares acquired (including 17.8591 shares acquired by dividend reinvestment) pursuant to the Company's Employee Stock Purchase Plan.</footnote>
        <footnote id="F2">Due to a clerical error, all options were previously erroneously reported as having been exercised on the Form 4 filed on May 11, 2016, when in fact the option remained unexercised solely with respect to 20 shares. The option was exercised with respect to those remaining 20 shares on August 18, 2017 prior to the option's expiration on August 20, 2017.</footnote>
        <footnote id="F3">All of these options are currently exercisable.</footnote>
        <footnote id="F4">29,163 of these options are currently exercisable and the remaining 9,721 options become exercisable on February 27, 2018, assuming continued employment through the applicable vesting date.</footnote>
        <footnote id="F5">Each restricted stock unit is convertible into a share of common stock on a 1-for-1 basis.</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 20, 2016, one-third of these restricted stock units vested on February 20, 2017 and the remaining one-third of these restricted stock units vest on February 20, 2018, assuming continued employment through the applicable vesting date.</footnote>
        <footnote id="F7">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 vest 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>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Rebecca C. Polak, as Attorney In Fact</signatureName>
        <signatureDate>2017-08-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
