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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-11-09</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001387632</issuerCik>
        <issuerName>Manhattan Bancorp</issuerName>
        <issuerTradingSymbol>MNHN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001552016</rptOwnerCik>
            <rptOwnerName>Jones James Bolton</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>5 PARK PLAZA</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 950</rptOwnerStreet2>
            <rptOwnerCity>IRVINE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92614</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-11-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>169424</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>9336700</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By: Limited Partnerships</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Stock option (right to buy Common Stock)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>5.55</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2009-03-09</value>
            </exerciseDate>
            <expirationDate>
                <value>2019-03-09</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>24108</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>24108</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By: Limited Partnerships</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Pursuant to and in accordance with the terms of that certain Credit Agreement dated July 25, 2011, as amended, Carpenter Community Bancfund, L.P. and Carpenter Community Bancfund-A, L.P. converted $716,667 of the outstanding balance of the loans outstanding under the credit agreement into an aggregate of 169,424 shares of the issuer's common stock.</footnote>
        <footnote id="F2">All such shares are held by Carpenter Community BancFund, L.P., Carpenter Community BancFund-A, L.P. and Carpenter Community BancFund-CA, L.P., of which Carpenter Fund Manager GP, LLC is the General Partner.  Mr. Jones is a Managing Member of Carpenter Fund Manager GP, LLC and disclaims beneficial ownership of all such shares, except to the extent that Mr. Jones has a pecuniary interest in the General Partner.</footnote>
        <footnote id="F3">All such stock options are held by Carpenter Community BancFund-A, L.P, of which Carpenter Fund Manager GP, LLC is the General Partner. Mr. Jones is a Managing Member of Carpenter Fund Manager GP, LLC and disclaims beneficial ownership of all such stock options, except to the extent that Mr. Jones has a pecuniary interest in the General Partner.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>James B. Jones</signatureName>
        <signatureDate>2012-11-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
