Merck Begins Tender Offer to Acquire Acceleron Pharma Inc. - Seite 2

Important Information About the Tender Offer

This press release is for informational purposes only and is neither an offer to purchase nor a solicitation of an offer to sell any shares of the common stock of Acceleron Pharma Inc. (“Acceleron”) or any other securities, nor is it a substitute for the tender offer materials described herein. A tender offer statement on Schedule TO, including an offer to purchase, a letter of transmittal and related documents, will be filed today by Merck Sharp & Dohme Corp. (“Merck”) and Astros Merger Sub, Inc., a wholly owned subsidiary of Merck, with the Securities and Exchange Commission (the “SEC”), and a solicitation/recommendation statement on Schedule 14D-9 will be filed by Acceleron with the SEC.

INVESTORS AND SECURITY HOLDERS ARE URGED TO READ CAREFULLY BOTH THE TENDER OFFER MATERIALS (INCLUDING AN OFFER TO PURCHASE, A RELATED LETTER OF TRANSMITTAL AND CERTAIN OTHER TENDER OFFER DOCUMENTS) AND THE SOLICITATION/RECOMMENDATION STATEMENT ON SCHEDULE 14D-9 REGARDING THE OFFER, AS THEY MAY BE AMENDED FROM TIME TO TIME, BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION THAT INVESTORS AND SECURITY HOLDERS SHOULD CONSIDER BEFORE MAKING ANY DECISION REGARDING TENDERING THEIR SECURITIES.

Investors and security holders may obtain a free copy of the Offer to Purchase, the related Letter of Transmittal, certain other tender offer documents and the Solicitation/Recommendation Statement (when available) and other documents filed with the SEC at the website maintained by the SEC at www.sec.gov or by directing such requests to the Information Agent for the offer, which will be named in the tender offer statement. In addition, Merck and Acceleron file annual, quarterly and current reports and other information with the SEC, which are available to the public from commercial document-retrieval services and at the SEC’s website at www.sec.gov. Copies of the documents filed with the SEC by Merck may be obtained at no charge on Merck’s internet website at www.merck.com or by contacting Merck at 2000 Galloping Hill Road, Kenilworth, N.J. 07033 or [phone]. Copies of the documents filed with the SEC by Acceleron may be obtained at no charge on Acceleron’s internet website at www.acceleronpharma.com or by contacting Acceleron at 128 Sidney Street, Cambridge, MA 02139 or [phone].