Repligen Corporation (NASDAQ:RGEN) today announced that the Company’s stock has been added to the Russell 2000 ® index, a subset of the Russell 3000 ® and the Russell Global ® indexes. Russell Investments’ annual index reconstitution was finalized on June 22, 2012. The Russell indexes are widely used by investment managers and institutional investors as proxies for asset allocation and as performance benchmarks for investment strategies. “We are pleased that Repligen has been added to the Russell 2000 index, and believe that our inclusion will enhance our visibility among institutions that rely on equity indexes as part of their investment strategy,” stated Walter C. Herlihy, Ph.D., President and Chief Executive Officer of Repligen. The Russell 2000 Index measures the performance of the small-cap segment of the U.S. equity universe. The Russell 2000 is a subset of the Russell 3000 Index and is constructed to provide a comprehensive and unbiased small-cap barometer. It is reconstituted annually to ensure larger stocks do not distort the performance and characteristics of the true small-cap opportunity set. Membership in the Russell 2000 also means automatic inclusion in the appropriate growth and value style indexes. Members of the Russell 2000 and 3000 are also included in the Russell Global Index, which measures the performance of the global equity market based on all investable equity securities. About Repligen Corporation Repligen Corporation is a leading supplier of critical biologic products used to manufacture biologic drugs. Repligen also applies its expertise in biologic product development to RG1068, a synthetic hormone being developed as a novel imaging agent for the diagnosis of a variety of pancreatic diseases. In addition, the Company has two central nervous system (CNS) rare disease programs in Phase 1 clinical trials. Repligen’s corporate headquarters are located at 41 Seyon Street, Building #1, Suite 100, Waltham, MA 02453. Additional information may be requested at www.repligen.com. This press release may contain forward-looking statements within the meaning of the federal securities laws. Investors are cautioned that statements in this press release which are not strictly historical statements including, without limitation, statements identified by words like “believe,” “expect,” “may,” “will,” “should,” “seek,” or “could” and similar expressions, constitute forward-looking statements. Such forward-looking statements are subject to a number of risks and uncertainties that could cause actual results to differ materially from those anticipated, including, risks discussed from time to time in our filings with the Securities and Exchange Commission. We expressly disclaim any responsibility to update forward-looking statements, except as required by law.