Biogen Enters Acquisition Battle for Rare Disease Drug, Secures Support from Major Shareholders

Biogen Inc. (NASDAQ: BIIB), together with its wholly owned subsidiary Aspen Purchaser Sub, on March 31 signed a stock purchase and support agreement with major shareholders of Apellis Pharmaceuticals Inc. (NASDAQ: APLS). Under the agreement, these shareholders have committed to tender all of their Apellis shares in the scheduled tender offer and to vote in favor of the merger. The pact— which involves Morningside Venture Investments and members of Apellis’s management—also restricts the sale of shares and any discussions with third parties, requires shareholders to vote against competing acquisition proposals, and grants Biogen proxy voting rights until the merger closes or the merger agreement is terminated.

On the same day, Biogen announced a merger agreement to acquire Apellis for about $5.6 billion in cash at $41 per share, plus contingent value rights of up to $4 per share, valuing the transaction at roughly ₩7 trillion. Following the announcement, Apellis’s stock surged more than 100% intraday, and some analysts raised their price targets on Biogen, citing the expanded rare disease and immunology portfolio.

Apellis is a commercial‐stage biotech company with therapies targeting the complement system for ophthalmic and autoimmune diseases—its lead product, Syfovre, treats macular degeneration–related eye conditions. Biogen, a major U.S. biotech firm built on multiple sclerosis and other central nervous system treatments, has been strategically diversifying its revenue base through recent acquisitions in Alzheimer’s, rare diseases, and immunology.