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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-03-08</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001001601</issuerCik>
        <issuerName>MGT CAPITAL INVESTMENTS INC</issuerName>
        <issuerTradingSymbol>MGTI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001168465</rptOwnerCik>
            <rptOwnerName>LOWREY ROBERT S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>512 S MAGNUM ST.</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 408</rptOwnerStreet2>
            <rptOwnerCity>DURHAM</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>27701</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CFO, Treasurer, Secretary</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>common stock, par value $0.001</value>
            </securityTitle>
            <transactionDate>
                <value>2018-03-08</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>750000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>750000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The securities were acquired through a grant pursuant to the employment agreement between MGT Capital Investments, Inc. and Mr. Robert S. Lowrey. The restricted stock was issued under the Company's 2016 Stock Option Plan and vests over 24 months with 33% vesting on each of March 8, 2019, September 8, 2019, and March 8, 2020.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Robert S. Lowrey, By: /s/ Robert S. Lowrey</signatureName>
        <signatureDate>2018-03-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
