<SEC-DOCUMENT>0001645383-19-000008.txt : 20190208
<SEC-HEADER>0001645383-19-000008.hdr.sgml : 20190208
<ACCEPTANCE-DATETIME>20190208185105
ACCESSION NUMBER:		0001645383-19-000008
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20190206
FILED AS OF DATE:		20190208
DATE AS OF CHANGE:		20190208

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Lewis Scott Richard
		CENTRAL INDEX KEY:			0001757430

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-32929
		FILM NUMBER:		19581437

	MAIL ADDRESS:	
		STREET 1:		2016 BECKETT DRIVE
		CITY:			EL DORADO HILLS
		STATE:			CA
		ZIP:			95762

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MoSys, Inc.
		CENTRAL INDEX KEY:			0000890394
		STANDARD INDUSTRIAL CLASSIFICATION:	SEMICONDUCTORS & RELATED DEVICES [3674]
		IRS NUMBER:				770291941
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2309 BERING DRIVE
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95131
		BUSINESS PHONE:		408 418 7500

	MAIL ADDRESS:	
		STREET 1:		2309 BERING DRIVE
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95131

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	MONOLITHIC SYSTEM TECHNOLOGY INC
		DATE OF NAME CHANGE:	19960613
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-02-06</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000890394</issuerCik>
        <issuerName>MoSys, Inc.</issuerName>
        <issuerTradingSymbol>MOSY</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001757430</rptOwnerCik>
            <rptOwnerName>Lewis Scott Richard</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2016 BECKETT DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>EL DORADO HILLS</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95762</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <transactionDate>
                <value>2019-02-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>20000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Restricted Stock Unit (&quot;RSU&quot;) award granted February 6, 2019. Each RSU represents a contingent right to receive one share of the Company's common stock once vested. The entire award vests and becomes non-forfeitable on February 6, 2020.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ C. Graves by Power of Attny</signatureName>
        <signatureDate>2019-02-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
