Biogen to Acquire Apellis Pharmaceuticals in a $5.6 Billion Deal

Biogen Inc. (BIIB) entered a merger agreement on March 31, 2026, to acquire Apellis Pharmaceuticals, Inc. (APLS) in a deal valued at $5.6 billion.

Deal Structure:

Biogen will commence a tender offer to acquire all of the outstanding shares of Apellis for $41 per share in cash and a non-transferable CVR per share. The cash consideration represents a premium of 139.91% from the stock’s last close.

Each CVR represents the right to receive a cash payment of $2 per share if Syfovre achieves $1.5 billion in annual global net sales in any year between 2027 and 2030, a right to receive an additional cash payment of $2 per share if Syfovre achieves $2 billion in annual global net sales in any of these years, and, if these thresholds are not met and no CVR payment is due for any of these years, but if Syfovre achieves $2 billion in annual global net sales in the 2031 calendar year, a cash payment of $4 per share.

Company Profile:

Apellis is a global biopharmaceutical company that develops treatments by targeting the complement system to address autoimmune, inflammatory, and rare diseases. It focuses on discovering, developing, and commercializing therapies, including C3 inhibitors, for conditions such as eye, kidney, blood, and neurodegenerative disorders.

Biogen is a biotechnology company that develops, manufactures, and markets therapies for neurological, neurodegenerative, and autoimmune diseases. It focuses on treatments for conditions such as multiple sclerosis, Alzheimer’s disease, spinal muscular atrophy, and other rare and chronic disorders.

Deal Details and Timeline:

Apellis brings two approved medicines, Empaveli and Syfovre, which are already being sold. Together, these drugs made $689 million in sales in 2025. Their sales are expected to keep growing at a rate of mid-to-high teens at least until 2028.

Empaveli is FDA-approved to treat rare immune-related kidney diseases (C3G and primary IC-MPGN) as well as a blood disorder called PNH. Syfovre is FDA-approved to treat geographic atrophy, an eye condition caused by age-related macular degeneration, which affects the retina and is linked to the immune system.

Biogen will continue its partnership with Sobi, which keeps the rights to sell Empaveli (called Aspaveli in the EU) outside the United States.

The deal is expected to close in the second quarter of 2026.

Biogen plans to pay for the acquisition using a mix of its own cash and borrowed money. It expects to pay off this debt completely by the end of 2027.

Evercore served as financial advisor to Apellis, while Wachtell, Lipton, Rosen & Katz and WilmerHale acted as its legal advisors. Lazard advised Biogen on the financial side, with Cravath, Swaine & Moore and Arnold & Porter providing legal counsel.

Deal Metrics:

For more details on this merger and acquisition transaction, visit the Deal Metrics page:

Deal Metrics for the acquisition of Apellis Pharmaceuticals, Inc. (APLS) by Biogen Inc. (BIIB)

The Deal Metrics page provides a comprehensive timeline of the merger, including a spread history chart, progress of regulatory approvals, shareholder votes, news and SEC filings, and a history of deal updates.

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Editor’s Note: Baranjot Kaur contributed to this article