<SEC-DOCUMENT>0001250853-18-000075.txt : 20180510
<SEC-HEADER>0001250853-18-000075.hdr.sgml : 20180510
<ACCEPTANCE-DATETIME>20180510163241
ACCESSION NUMBER:		0001250853-18-000075
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20180508
FILED AS OF DATE:		20180510
DATE AS OF CHANGE:		20180510

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			EDDLEMAN ROY T
		CENTRAL INDEX KEY:			0001270264

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-14656
		FILM NUMBER:		18823068

	MAIL ADDRESS:	
		STREET 1:		110 W. GEORGE BURNS ROAD
		STREET 2:		SUITE D-4018
		CITY:			LOS ANGELES
		STATE:			CA
		ZIP:			90048

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			REPLIGEN CORP
		CENTRAL INDEX KEY:			0000730272
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		IRS NUMBER:				042729386
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		41 SEYON STREET
		STREET 2:		BUILDING 1, SUITE 100
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02453
		BUSINESS PHONE:		7814499560

	MAIL ADDRESS:	
		STREET 1:		41 SEYON STREET
		STREET 2:		BUILDING 1, SUITE 100
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02453
</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>2018-05-08</periodOfReport>

    <dateOfOriginalSubmission>2018-05-09</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000730272</issuerCik>
        <issuerName>REPLIGEN CORP</issuerName>
        <issuerTradingSymbol>RGEN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001270264</rptOwnerCik>
            <rptOwnerName>EDDLEMAN ROY T</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TROYGOULD PC</rptOwnerStreet1>
            <rptOwnerStreet2>1801 CENTURY PARK E., 16TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90067</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-05-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>49227</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>40.77</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>850773</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>As trustee</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-05-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>25000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>40.66</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>455000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>As trustee</value>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-05-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>20773</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>40.52</value>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>830000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>As trustee</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-05-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>25000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>40.37</value>
                    <footnoteId id="F6"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>430000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>As trustee</value>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>357518</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F7"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3044826</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>As trustee</value>
                    <footnoteId id="F8"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The price is a weighted-average price.  The shares were sold in multiple transactions at prices ranging from $40.5515 to $41.0078, inclusive.  The reporting person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the SEC, upon request, full information regarding the number of shares sold at each price within the price ranges set forth in this footnote (1) and in footnotes (3) - (5)  to this Form 4.</footnote>
        <footnote id="F2">The shares shown are held, of record, by a charitable remainder unitrust of which the reporting person is the sole trustee and, as such, has investment and voting control over such shares, and is a lifetime beneficiary.  The reporting person disclaims as beneficial ownership of the shares except to the extent of his pecuniary interest therein.</footnote>
        <footnote id="F3">The price is a weighted-average price.  The shares were sold in multiple transactions at prices ranging from $40.5607 to $41.0107, inclusive.</footnote>
        <footnote id="F4">The shares shown are held, of record, by another charitable remainder unitrust of which the reporting person is the sole trustee and, as such, has investment and voting control over such shares, and is a lifetime beneficiary.  The reporting person disclaims as beneficial ownership of the shares except to the extent of his pecuniary interest therein.</footnote>
        <footnote id="F5">The price is a weighted-average price.  The shares were sold in multiple transactions at prices ranging from $40.2401 to $40.70, inclusive.</footnote>
        <footnote id="F6">The price is a weighted-average price.  The shares were sold in multiple transactions at prices ranging from $40.2102 to $40.6022, inclusive.</footnote>
        <footnote id="F7">The shares shown are held for the benefit of the reporting person in a 15-month escrow account established in connection with the acquisition of Spectrum, Inc. by the issuer on August 1, 2017 and are subject to potential indemnification claims of the issuer relating to the acquisition.</footnote>
        <footnote id="F8">The shares shown are held of record by the Roy T. Eddleman Living Trust UAD 8-7-2000, of which the reporting person is the sole trustee, and as such, has investment and voting control over such shares.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Istvan Benko, Attorney-in-fact for Roy T. Eddleman</signatureName>
        <signatureDate>2018-05-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
