Alnylam Pharmaceuticals, Inc. (Nasdaq:ALNY), a leading RNAi therapeutics company, today announced that it has commenced an underwritten public offering of shares of its common stock to raise aggregate proceeds of approximately $450 million. All of the shares in the offering are to be sold by Alnylam. J.P. Morgan Securities LLC and Deutsche Bank Securities Inc. are acting as joint book-running managers for the offering. Alnylam intends to grant the underwriters a 30 day option to purchase up to an additional 15% of the number of shares sold. The offering is subject to market conditions, and there can be no assurance as to whether or when the offering may be completed, or as to the actual size or terms of the offering. Alnylam intends to use the net proceeds from this offering for general corporate purposes, focused on achieving its Alnylam 2020 profile with 3 marketed products, 10 RNAi therapeutic clinical programs, including 4 in late stages of development, across its 3 Strategic Therapeutic Areas, or "STArs" - Genetic Medicines, Cardio-Metabolic Disease, and Hepatic Infectious Disease - by the end of 2020. Alnylam expects these purposes to include research and development expenses, including clinical trial costs, potential acquisitions of new businesses, technologies or products Alnylam believes have the potential to complement or expand its business, working capital, capital expenditures and general and administrative expenses. The securities described above are being offered by Alnylam pursuant to an automatically effective shelf registration statement that Alnylam previously filed with the Securities and Exchange Commission (SEC). This press release shall not constitute an offer to sell or the solicitation of an offer to buy any securities nor shall there be any sale of these securities in any state in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of such state. The offering of these securities will be made only by means of a prospectus and the related prospectus supplement. Before you invest, you should read the prospectus and the related prospectus supplement and any other document Alnylam has filed with the SEC for more complete information about Alnylam and this offering. You may get these documents for free by visiting EDGAR on the SEC website at www.sec.gov. Alternatively, copies of these documents may be obtained by contacting J.P. Morgan Securities LLC, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, New York 11717, via telephone at (866) 803-9204; or Deutsche Bank Securities Inc., Attention: Prospectus Department, 60 Wall Street, New York, NY 10005, via telephone at (800) 503-4611 or email at email@example.com. About Alnylam Pharmaceuticals Alnylam is a biopharmaceutical company developing novel therapeutics based on RNA interference, or RNAi. The company is leading the translation of RNAi as a new class of innovative medicines. Alnylam's pipeline of investigational RNAi therapeutics is focused in 3 Strategic Therapeutic Areas (STArs): Genetic Medicines, with a broad pipeline of RNAi therapeutics for the treatment of rare diseases; Cardio-Metabolic Disease, with a pipeline of RNAi therapeutics toward genetically validated, liver-expressed disease targets for unmet needs in cardiovascular and metabolic diseases; and Hepatic Infectious Disease, with a pipeline of RNAi therapeutics that address the major global health challenges of hepatic infectious diseases. In early 2015, Alnylam launched its "Alnylam 2020" guidance for the advancement and commercialization of RNAi therapeutics as a whole new class of innovative medicines. Specifically, by the end of 2020, Alnylam expects to achieve a company profile with 3 marketed products, 10 RNAi therapeutic clinical programs - including 4 in late stages of development - across its 3 STArs. The company's demonstrated commitment to RNAi therapeutics has enabled it to form major alliances with leading companies including Merck, Medtronic, Novartis, Biogen Idec, Roche, Takeda, Kyowa Hakko Kirin, Cubist, GlaxoSmithKline, Ascletis, Monsanto, The Medicines Company, and Genzyme, a Sanofi company. In addition, Alnylam holds an equity position in Regulus Therapeutics Inc., a company focused on discovery, development, and commercialization of microRNA therapeutics. Alnylam scientists and collaborators have published their research on RNAi therapeutics in over 200 peer-reviewed papers, including many in the world's top scientific journals such as Nature, Nature Medicine, Nature Biotechnology, Cell, New England Journal of Medicine, and The Lancet. Founded in 2002, Alnylam maintains headquarters in Cambridge, Massachusetts. Alnylam Forward-Looking Statements Statements in this release concerning Alnylam's future expectations, plans and prospects, including, without limitation, Alnylam's intention to publicly offer shares of its common stock and its expectations regarding future company achievements, constitute forward-looking statements for the purposes of the safe harbor provisions under The Private Securities Litigation Reform Act of 1995. Actual results may differ materially from those indicated by these forward-looking statements as a result of various important factors, including, without limitation, risks related to fluctuations in our stock price, those associated with market conditions and the satisfaction of customary closing conditions related to the proposed offering, as well as those risks more fully discussed in the "Risk Factors" filed with Alnylam's most recent Quarterly Report on Form 10-Q filed with the SEC and in other filings that Alnylam makes with the SEC. There can be no assurance that Alnylam will be able to complete the proposed public offering on the anticipated terms, or at all. You should not place undue reliance on these forward-looking statements. In addition, any forward-looking statements represent Alnylam's views only as of today and should not be relied upon as representing its views as of any subsequent date. Alnylam explicitly disclaims any obligation to update any forward-looking statements.