On Mar. 31, 2026, Biogen and Apellis Pharmaceuticals announced the companies have entered into a definitive agreement under which Biogen has agreed to acquire all outstanding shares of Apellis for $41.00 per share in cash at closing, or approximately $5.6 billion.

Apellis stockholders will also receive a nontransferable CVR for each Apellis share held, entitling the holder to receive two payments of $2 per share each, contingent on certain annual global net sales thresholds being met for SYFOVRE^®.

The addition of Apellis, a leader in advancing treatments for serious, complement-driven diseases, is expected to enhance Biogen’s short- and long-term revenue growth profile by adding two commercialized 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 $689 million in 2025, which is expected to grow at a rate in the mid-to-high teens at least through 2028.

EMPAVELI^® is FDA-approved in rare immune-mediated kidney diseases (C3G and primary IC-MPGN) and in PNH and SYFOVRE^® is FDA-approved in geographic atrophy secondary to age related macular degeneration, an immune-mediated retinal disease.

Apellis brings an established U.S. sales infrastructure and capabilities, including in nephrology, that Biogen believes will accelerate and strengthen Biogen’s commercial readiness for felzartamab, which is currently in Phase 3 studies for three kidney diseases with the first trial readout expected in the first half of 2027. Upon closing, Biogen expects a significant proportion of Apellis employees to join the company. Biogen will continue to work with Sobi, which retains commercial rights to EMPAVELI^® (Aspaveli^® in the EU) outside the U.S.