<SEC-DOCUMENT>0001645383-17-000028.txt : 20171102
<SEC-HEADER>0001645383-17-000028.hdr.sgml : 20171102
<ACCEPTANCE-DATETIME>20171102142854
ACCESSION NUMBER:		0001645383-17-000028
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20171019
FILED AS OF DATE:		20171102
DATE AS OF CHANGE:		20171102

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Lewis Daniel Lee
		CENTRAL INDEX KEY:			0001718088

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-32929
		FILM NUMBER:		171171757

	MAIL ADDRESS:	
		STREET 1:		166 W PEARL STREET
		CITY:			COLDWATER
		STATE:			MI
		ZIP:			49036

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:		3301 OLCOTT STREET
		CITY:			SANTA CLARA
		STATE:			CA
		ZIP:			95054
		BUSINESS PHONE:		408 418 7500

	MAIL ADDRESS:	
		STREET 1:		3301 OLCOTT STREET
		CITY:			SANTA CLARA
		STATE:			CA
		ZIP:			95054

	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>2017-10-19</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001718088</rptOwnerCik>
            <rptOwnerName>Lewis Daniel Lee</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>166 W PEARL STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>COLDWATER</rptOwnerCity>
            <rptOwnerState>MI</rptOwnerState>
            <rptOwnerZipCode>49036</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Option to purchase common stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.75</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-10-19</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>80000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.75</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2018-09-26</value>
            </exerciseDate>
            <expirationDate>
                <value>2023-10-19</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>80000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>80000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Options vest on each anniversary of September 26, 2017 at the rate of 1/3 of the total number of shares subject to the option.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>C.Leitner by power of attny</signatureName>
        <signatureDate>2017-11-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
