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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2013-10-29</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001411574</issuerCik>
        <issuerName>ASC Acquisition LLC</issuerName>
        <issuerTradingSymbol>NONE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001199421</rptOwnerCik>
            <rptOwnerName>CLEMENS PETER J IV</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ASC ACQUISITION LLC</rptOwnerStreet1>
            <rptOwnerStreet2>520 LAKE COOK ROAD, SUITE 250</rptOwnerStreet2>
            <rptOwnerCity>DEERFIELD</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60015</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Financial Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Options to Purchase Membership Units</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F3"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2021-12-08</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Membership Units</value>
                    <footnoteId id="F1"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1500000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Options to Purchase Membership Units</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.21</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2023-05-06</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Membership Units</value>
                    <footnoteId id="F1"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>225000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The Issuer expects to complete an initial public offering of common stock on or about November 4, 2013 (the &quot;IPO&quot;), and in connection therewith, the Issuer is being converted into a Delaware corporation (the &quot;Reorganization&quot;) named Surgical Care Affiliates, Inc. (&quot;SCA&quot;). As part of the Reorganization, options to purchase the membership units of the Issuer (the &quot;Membership Units&quot;), including the options reported herein, will be converted into options to purchase shares of common stock of SCA, par value $0.01 per share (the &quot;Common Stock&quot;), at a conversion ratio of options to purchase 10.25 Membership Units to an option to purchase one share of Common Stock. In connection with the Reorganization, the exercise prices of such converted options will be adjusted accordingly. As part of the IPO, the Common Stock is expected to be listed on the NASDAQ Stock Market under the symbol &quot;SCAI&quot;.</footnote>
        <footnote id="F2">750,000 of the options are performance-based options and, as of September 16, 2013, are fully vested. The remaining 750,000 options are time-based options, which are scheduled to vest in equal installments of 20% on each of December 8, 2012, December 8, 2013, December 8, 2014, December 8, 2015, and December 8, 2016.</footnote>
        <footnote id="F3">The 900,000 vested options have an exercise price of $1.18 per option to purchase a membership unit. The 600,000 unvested options have an exercise price of $0.94 per option to purchase a membership unit.</footnote>
        <footnote id="F4">The options are time-based options and are scheduled to vest in equal installments of 25% on each of May 6, 2014, May 6, 2015, May 6, 2016, and May 6, 2017.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Peter J. Clemens IV</signatureName>
        <signatureDate>2013-10-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
