Biogen to buy Apellis Pharmaceuticals in $5.6bn deal

(Sharecast News) - Shares in Apellis Pharmaceuticals rocketed on Tuesday after it agreed to be bought by Biogen in a $5.6bn deal. Under the terms of the acquisition, Biogen will pay $41 per share in cash.

Apellis stockholders will also receive a non-transferable CVR for each Apellis share held, entitling the holder to receive two payments of $2 per share each. This is contingent on certain annual global net sales thresholds being met for Syfovre, which is used for the treatment of macular degeneration.

Biogen said the addition of Apellis, a leader in advancing treatments for serious, complement-driven diseases, is expected to enhance its short- and long-term revenue growth profile by adding two commercialised differentiated immunology and rare disease medicines to its growth portfolio.

Empaveli and Syfovre add immediate sales revenue to Biogen, having achieved combined net sales of $689m in 2025. This is expected to grow at a rate in the mid-to-high teens at least through 2028, Biogen said.

Empaveli is FDA-approved in rare immune-mediated kidney diseases, while Syfovre is FDA-approved in geographic atrophy secondary to age related macular degeneration.

Biogen president and chief executive Christopher A. Viehbacher said: "Consistent with our strategy, this acquisition immediately advances Biogen's ongoing transformation. The addition of Apellis expands our growth portfolio in immunology and rare disease with two approved, best-in-class medicines that complement our existing portfolio and bolsters our near-and long-term growth potential."

At 1530 BST, Apellis shares were up 136% at $40.28. Biogen was 4.7% lower at $178.70.