<SEC-DOCUMENT>0001192381-15-000019.txt : 20150220
<SEC-HEADER>0001192381-15-000019.hdr.sgml : 20150220
<ACCEPTANCE-DATETIME>20150220200105
ACCESSION NUMBER:		0001192381-15-000019
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20150210
FILED AS OF DATE:		20150220
DATE AS OF CHANGE:		20150220

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			LAM RESEARCH CORP
		CENTRAL INDEX KEY:			0000707549
		STANDARD INDUSTRIAL CLASSIFICATION:	SPECIAL INDUSTRY MACHINERY, NEC [3559]
		IRS NUMBER:				942634797
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0630

	BUSINESS ADDRESS:	
		STREET 1:		4650 CUSHING BLVD
		CITY:			FREMONT
		STATE:			CA
		ZIP:			94538
		BUSINESS PHONE:		5106590200

	MAIL ADDRESS:	
		STREET 1:		4650 CUSHING PARKWAY
		CITY:			FREMONT
		STATE:			CA
		ZIP:			94538

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Bettinger Douglas R
		CENTRAL INDEX KEY:			0001469469

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-12933
		FILM NUMBER:		15637304

	MAIL ADDRESS:	
		STREET 1:		C/O LAM RESEARCH CORPORATION
		STREET 2:		4650 CUSHING PARKWAY
		CITY:			FREMONT
		STATE:			CA
		ZIP:			94538
</SEC-HEADER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2015-02-10</periodOfReport>

    <dateOfOriginalSubmission>2015-02-12</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000707549</issuerCik>
        <issuerName>LAM RESEARCH CORP</issuerName>
        <issuerTradingSymbol>LRCX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001469469</rptOwnerCik>
            <rptOwnerName>Bettinger Douglas R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>4650 CUSHING PARKWAY</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>FREMONT</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94538</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP, Chief Financial Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2015-02-10</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3662</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>79.9</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>33718</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Shares sold pursuant to 10b5-1 Trading Plan.</footnote>
        <footnote id="F2">The stock option exercise, and sale of common stock acquired upon such exercise, of 3,740 shares pursuant to a 10b5-1 Trading Plan that were reported in a Form 4 filed on February 12, 2015 (the &quot;Form 4&quot;), which the broker acknowledged were erroneously executed without the reporting person's involvement due to the broker's error, were undone through the broker's error account and therefore did not occur for the reporting person's account. After nullifying the erroneous transactions, and following the sale of 3,662 shares also reported in the Form 4, the reporting person owned 33,718 shares of common stock, including shares subject to unvested Restricted Stock Units, and held Employee Stock Options subject to 57,096 shares.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Aaron Beckman by Power of Attorney</signatureName>
        <signatureDate>2015-02-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
