<SEC-DOCUMENT>0001193125-18-150937.txt : 20180503
<SEC-HEADER>0001193125-18-150937.hdr.sgml : 20180503
<ACCEPTANCE-DATETIME>20180503165433
ACCESSION NUMBER:		0001193125-18-150937
CONFORMED SUBMISSION TYPE:	DEFA14A
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20180503
DATE AS OF CHANGE:		20180503
EFFECTIVENESS DATE:		20180503

FILER:

	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

	FILING VALUES:
		FORM TYPE:		DEFA14A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-14656
		FILM NUMBER:		18804646

	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>DEFA14A
<SEQUENCE>1
<FILENAME>d582886ddefa14a.htm
<DESCRIPTION>DEFA14A
<TEXT>
<HTML><HEAD>
<TITLE>DEFA14A</TITLE>
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<Center><DIV STYLE="width:8.5in" align="left">
 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:14pt; font-family:Times New Roman" ALIGN="center"><B>UNITED STATES </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:14pt; font-family:Times New Roman" ALIGN="center"><B>SECURITIES AND EXCHANGE COMMISSION </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>Washington, D.C. 20549 </B></P>
<P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>SCHEDULE 14A </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(Rule <FONT
STYLE="white-space:nowrap">14a-101)</FONT> </B></P> <P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Information Required in Proxy Statement </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Schedule 14A Information </B></P>
<P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>Proxy Statement Pursuant to Section&nbsp;14(a) of the </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>Securities Exchange Act of 1934 </B></P>
<P STYLE="margin-top:4pt; margin-bottom:0pt; margin-left:2%; text-indent:-2%; font-size:10pt; font-family:Times New Roman">Filed by the Registrant &#9745; </P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:2%; text-indent:-2%; font-size:10pt; font-family:Times New Roman">Filed by a Party other than the Registrant &#9744; </P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:2%; text-indent:-2%; font-size:10pt; font-family:Times New Roman">Check the appropriate box: </P> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">


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<TD VALIGN="top">&#9744;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Preliminary Proxy Statement</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">&#9744;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Confidential, for Use of the Commission</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Only
(as permitted by Rule <FONT STYLE="white-space:nowrap">14a-6(e)(2))</FONT></P></TD></TR>
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<TD VALIGN="top">&#9744;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">Definitive Proxy Statement</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD></TR>
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<TD VALIGN="top">&#9745;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">Definitive Additional Materials</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD></TR>
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<TD VALIGN="top">&#9744;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">Soliciting Material Pursuant to <FONT STYLE="white-space:nowrap">&#167;240.14a-12</FONT></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
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<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
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</TABLE> <P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:24pt; font-family:Times New Roman" ALIGN="center"><B>REPLIGEN CORPORATION </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Name of Registrant as Specified in its Charter) </B></P> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</B></P>
<P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Name of Person(s) Filing Proxy
Statement, if other than the Registrant) </B></P> <P STYLE="margin-top:4pt; margin-bottom:0pt; margin-left:2%; text-indent:-2%; font-size:10pt; font-family:Times New Roman">Payment of Filing Fee (Check the appropriate box): </P>
<P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR style = "page-break-inside:avoid">
<TD WIDTH="4%" VALIGN="top" ALIGN="left">&#9745;</TD>
<TD ALIGN="left" VALIGN="top">No fee required. </TD></TR></TABLE> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="4%" VALIGN="top" ALIGN="left">&#9744;</TD>
<TD ALIGN="left" VALIGN="top">Fee computed on table below per Exchange Act Rules <FONT STYLE="white-space:nowrap">14a-6(i)&nbsp;(4)</FONT> and <FONT STYLE="white-space:nowrap">0-11.</FONT> </TD></TR></TABLE>
<P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(1)</TD>
<TD ALIGN="left" VALIGN="top">Title of each class of securities to which transaction applies: </TD></TR></TABLE> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">&nbsp;&nbsp;</P> <P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:2pt;margin-left:7%;border-bottom:1px solid #000000">&nbsp;</P>
<P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(2)</TD>
<TD ALIGN="left" VALIGN="top">Aggregate number of securities to which transaction applies: </TD></TR></TABLE> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">&nbsp;&nbsp;</P> <P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:2pt;margin-left:7%;border-bottom:1px solid #000000">&nbsp;</P>
<P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(3)</TD>
<TD ALIGN="left" VALIGN="top">Per unit price or other underlying value of transaction computed pursuant to Exchange Act Rule <FONT STYLE="white-space:nowrap">0-11</FONT> (set forth the amount on which the filing fee is calculated and state how it
was determined): </TD></TR></TABLE> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">&nbsp;&nbsp;</P>
<P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:2pt;margin-left:7%;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(4)</TD>
<TD ALIGN="left" VALIGN="top">Proposed maximum aggregate value of transaction: </TD></TR></TABLE> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">&nbsp;&nbsp;</P> <P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:2pt;margin-left:7%;border-bottom:1px solid #000000">&nbsp;</P>
<P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(5)</TD>
<TD ALIGN="left" VALIGN="top">Total fee paid: </TD></TR></TABLE> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">&nbsp;&nbsp;</P>
<P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:2pt;margin-left:7%;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="4%" VALIGN="top" ALIGN="left">&#9744;</TD>
<TD ALIGN="left" VALIGN="top">Fee paid previously with preliminary materials. </TD></TR></TABLE> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="4%" VALIGN="top" ALIGN="left">&#9744;</TD>
<TD ALIGN="left" VALIGN="top">Check box if any part of the fee is offset as provided by Exchange Act Rule <FONT STYLE="white-space:nowrap">0-11(a)(2)</FONT> and identify the filing for which the offsetting fee was paid previously. Identify the
previous filing by registration statement number, or the Form or Schedule and the date of its filing. </TD></TR></TABLE> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(1)</TD>
<TD ALIGN="left" VALIGN="top">Amount Previously Paid: </TD></TR></TABLE> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">&nbsp;&nbsp;</P>
<P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:2pt;margin-left:7%;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(2)</TD>
<TD ALIGN="left" VALIGN="top">Form, Schedule or Registration Statement No.: </TD></TR></TABLE> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">&nbsp;&nbsp;</P> <P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:2pt;margin-left:7%;border-bottom:1px solid #000000">&nbsp;</P>
<P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(3)</TD>
<TD ALIGN="left" VALIGN="top">Filing Party: </TD></TR></TABLE> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">&nbsp;&nbsp;</P>
<P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:2pt;margin-left:7%;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(4)</TD>
<TD ALIGN="left" VALIGN="top">Date Filed: </TD></TR></TABLE> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">&nbsp;&nbsp;</P>
<P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:2pt;margin-left:7%;border-bottom:1px solid #000000">&nbsp;</P>
</DIV></Center>


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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>REPLIGEN CORPORATION </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>SUPPLEMENT TO PROXY STATEMENT FOR </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>THE ANNUAL MEETING OF STOCKHOLDERS </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>To Be Held On May&nbsp;16, 2018 </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="right">May 3, 2018 </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">On April&nbsp;20,
2018, Repligen Corporation (the &#147;<U>Company</U>&#148;) filed a definitive proxy statement (the &#147;<U>Proxy Statement</U>&#148;) for its 2018 Annual Meeting of Stockholders (the &#147;<U>Annual Meeting</U>&#148;), to be held on Wednesday,
May&nbsp;16, 2018, at 8:00 a.m. EDT at the Company&#146;s headquarters located at 41 Seyon Street, Building 1, Suite 100, Waltham, Massachusetts 02453. This supplement (this &#147;<U>Supplement</U>&#148;) to the Proxy Statement amends and
supplements the Proxy Statement as filed and should be read in conjunction with the Proxy Statement. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Proposal 4 (the &#147;<U>Plan
Proposal</U>&#148;) of the Proxy Statement requests that the Company&#146;s stockholders approve the Repligen Corporation 2018 Stock Option and Incentive Plan (the &#147;<U>2018 Plan</U>&#148;), which was approved by the Company&#146;s Board of
Directors on April&nbsp;3, 2018. After making the Proxy Statement available to stockholders, the Company was informed by Institutional Shareholder Services (&#147;<U>ISS</U>&#148;) that the 2018 Plan received an unfavorable recommendation, in part
because the shareholder value transfer (&#147;<U>SVT</U>&#148;) for the 2018 Plan, as determined by ISS using its proprietary model with the Company&#146;s, is greater than the benchmark calculated by ISS. In calculating the SVT for the 2018 Plan,
ISS included shares available for issuance under the Company&#146;s Amended and Restated 2012 Repligen Corporation Stock Option and Incentive Plan (the &#147;<U>2012 Plan</U>&#148;) as of December&nbsp;31, 2017. Between December 31, 2017 and March
31, 2018 the number of shares available for issuance under the 2012 Plan decreased, and as of March 31, 2018 there were 254,907 shares available for issuance under the 2012 Plan. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman"><B>Accordingly, the Company&#146;s Board of Directors recommends that stockholders vote FOR the approval of the 2018 Plan.</B> </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Any vote &#147;FOR&#148; or &#147;AGAINST&#148; Proposal 4 for approval of the 2018 Plan described in the Proxy Statement using the proxy
materials previously furnished by the Company (or a beneficial owner&#146;s broker, bank, or other nominee) will continue to be counted as a vote &#147;FOR&#148; or &#147;AGAINST&#148; such proposal. If any stockholder has already voted and would
like to change his or her vote on any matter, such stockholder may revoke his or her proxy before it is voted at the Annual Meeting by (1)&nbsp;giving written notice of revocation to the Secretary of the Company at any time before the taking of the
vote at the Annual Meeting; (2)&nbsp;duly executing a later-dated proxy card relating to the same shares and delivering it to the Secretary of the Company or by telephone or the Internet, in accordance with the instructions listed on the proxy card;
or (3)&nbsp;attending the Annual Meeting and voting in person (although attendance at the Annual Meeting will not in and of itself constitute a revocation of a proxy). For those stockholders who submit a proxy by telephone or the Internet, the date
on which the proxy is submitted in accordance with the instructions listed on the proxy card is deemed to be the date of the proxy. Any written notice of revocation or subsequent proxy should be sent so as to be delivered to Repligen Corporation,
Attention: Secretary, 41 Seyon Street, Building #1, Suite 100, Waltham, Massachusetts 02453, at or before the taking of the vote at the Annual Meeting. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The cost of solicitation of proxies will be borne by the Company and, in addition to directly soliciting stockholders by mail, the Company may
request banks and brokers to solicit their customers who have stock of the Company registered in the name of the nominee and, if so, will reimburse such banks and brokers for their reasonable <FONT STYLE="white-space:nowrap"><FONT
STYLE="white-space:nowrap">out-of-pocket</FONT></FONT> costs. Solicitation by officers and employees of the Company may also be made of some stockholders in person or by mail or telephone following the original solicitation. The Company has retained
Innisfree M&amp;A Incorporated to aid in soliciting proxies and advise on certain matters relating to the Annual Meeting for a fee estimated not to exceed $20,000. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">This Supplement to the Proxy Statement is being released on or about May 3, 2018, and should be read in conjunction with the Proxy Statement.
The information contained in this Supplement to the Proxy Statement modifies or supersedes any inconsistent information contained in the Proxy Statement. The information provided above may be deemed &#147;additional soliciting materials&#148; within
the meaning of the Securities Exchange Act of 1934, as amended. </P>

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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>Important Information </B></P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">In connection with the solicitation of proxies, the Company filed the Proxy Statement on April&nbsp;20, 2018 with the U.S. Securities and Exchange Commission
(the &#147;<U>SEC</U>&#148;). Stockholders can access the Proxy Statement and other proxy materials and vote at <I>www.proxyvote.com</I>. THE COMPANY&#146;S STOCKHOLDERS ARE STRONGLY ADVISED TO READ THE PROXY STATEMENT AND ANY OTHER RELEVANT
SOLICITATION MATERIALS FILED BY THE COMPANY WITH THE SEC BEFORE MAKING ANY VOTING OR INVESTMENT DECISION BECAUSE THESE DOCUMENTS CONTAIN IMPORTANT INFORMATION. In addition, the Company files annual, quarterly and current reports with the SEC. These
reports can be obtained free of charge at the SEC&#146;s web site at <I>www.sec.gov</I> or from the Company&#146;s website at <I>http://www.repligen.com</I>. The Proxy Statement, copies of other solicitation materials and these other reports the
Company files with the SEC can be obtained at no charge by writing to Repligen Corporation, Attention: Secretary, 41 Seyon Street, Building #1, Suite 100, Waltham, MA 02453. </P>
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