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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-01-06</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001350773</issuerCik>
        <issuerName>Ascend Acquisition Corp.</issuerName>
        <issuerTradingSymbol>ASCQ</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001298983</rptOwnerCik>
            <rptOwnerName>Weiss Asset Management LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>29 COMMONWEALTH AVENUE, 10TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>66245</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Commonly referred to as Total Return Swaps (&quot;TRS&quot;)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F4"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2010-01-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>1</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1788</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.05</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1788</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>37712</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Shares and Swaps reported herein are owned by a private investment partnership (the &quot;Partnership&quot;) of which Weiss Asset Management LLC is the General Partner. Weiss Asset Management LLC disclaims beneficial ownership of the Shares and Swaps reported herein except to the extent of its pecuniary interest therein.</footnote>
        <footnote id="F2">The Partnership has entered into certain cash-settled total return swap agreements (each a &quot;Swap&quot;) with certain counterparties. Each Swap has an indeterminate termination date and refers to a notional number of shares of Common Stock (&quot;reference shares&quot;) of the Issuer as set forth in Table II and the applicable footnotes thereto. Under each Swap, at termination, the counterparty is obligated to pay to the Partnership, and the Partnership is obligated to pay the respective counterparty, in cash, amounts that are determined in part by reference to any increase or decrease between an initial reference price per share and the market value of such reference shares on the applicable termination date.</footnote>
        <footnote id="F3">None of the Swaps provides for the Partnership or the Reporting Person to have direct or indirect voting, investment or dispositive control over any reference shares and, accordingly, except to the extent of its pecuniary interest therein, the Reporting Person disclaims any beneficial ownership in any reference shares or other securities, if any, which may be owned by the counterparties to such Swaps.</footnote>
        <footnote id="F4">There is no set Conversion or Exercise Price of the Derivative Securities, which are structured as Swaps.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Georgiy Nikitin, Chief Compliance Officer</signatureName>
        <signatureDate>2010-01-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
