<SEC-DOCUMENT>0001645383-17-000021.txt : 20171016
<SEC-HEADER>0001645383-17-000021.hdr.sgml : 20171016
<ACCEPTANCE-DATETIME>20171016153636
ACCESSION NUMBER:		0001645383-17-000021
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20171013
FILED AS OF DATE:		20171016
DATE AS OF CHANGE:		20171016

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Perham Leonard charles
		CENTRAL INDEX KEY:			0001296527

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-32929
		FILM NUMBER:		171138660

	MAIL ADDRESS:	
		STREET 1:		PO BOX 2610
		CITY:			SARATOGA
		STATE:			CA
		ZIP:			95070

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>2017-10-13</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001296527</rptOwnerCik>
            <rptOwnerName>Perham Leonard charles</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>PO BOX 2610</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SARATOGA</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95070</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Option to purchase common stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>20.5</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-10-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>25000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2025-03-30</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>25000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Option to purchase common stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>44.6</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-10-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2023-06-06</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>10000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Option to purchase common stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>35.4</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-10-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>20000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2017-11-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>20000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On October 13, 2017, the reporting person and the Company agreed to cancel a stock option granted on March 30, 2015 to purchase 25,000 shares of common stock. The option was previously reported on a Form 4 filed with the SEC on April 2, 2015. The canceled option was exercisable in full as of January 1, 2017 . Shares and price have been adjusted for to reflect 1-for-10 reverse stock split effected in February 2017.</footnote>
        <footnote id="F2">On October 13, 2017, the reporting person and the Company agreed to cancel a stock option granted on June 6, 2013 to purchase 10,000 shares of common stock. The option was previously reported on a Form 4 filed with the SEC on June 10, 2013. The canceled option was exercisable in full as of April 1, 2017. Shares and price have been adjusted for to reflect 1-for-10 reverse stock split effected in February 2017.</footnote>
        <footnote id="F3">On October 13, 2017, the reporting person and the Company agreed to cancel a stock option granted on November 1, 2011 to purchase 20,000 shares of common stock. The option was previously reported on a Form 4 filed with the SEC on November 4, 2011. The canceled option was exercisable in full as of November 1, 2013 . Shares and price have been adjusted for to reflect 1-for-10 reverse stock split effected in February 2017.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>C.Leitner by power of attny</signatureName>
        <signatureDate>2017-10-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
