Biogen agreed on 31 March 2026 to acquire Apellis Pharmaceuticals for US$41.00 per share in cash, or about US$5.6bn, plus a contingent value right tied to sales of the eye drug Syfovre.
Why Biogen Inc. is buying Apellis Pharmaceuticals, Inc.
Biogen said Apellis adds two approved immunology and rare-disease medicines: Empaveli, approved in two rare kidney diseases and PNH, and Syfovre, approved in geographic atrophy. Together they generated US$689m of net product revenue in 2025. Apellis' US nephrology infrastructure is expected to support the launch of Biogen's felzartamab, which is in Phase 3.
“Consistent with our strategy, this acquisition immediately advances Biogen’s ongoing transformation.”
Deal terms and financing
The cash price represented an 86% premium to Apellis' 90-day volume-weighted average share price and a 35% premium to its 52-week high. The CVR pays US$2 per share if Syfovre reaches US$1.5bn of annual global net sales in any year from 2027 to 2030 and a further US$2 at US$2bn, or US$4 if the US$2bn threshold is first met in 2031. Biogen financed the deal with cash and borrowings and expects it to add to non-GAAP earnings per share from 2027.
Regulatory approvals and timing
The tender offer needed a majority of Apellis shares and US antitrust clearance. It expired on 13 May with about 82.4% of shares tendered, and Biogen announced completion on 14 May 2026, making Apellis a wholly owned subsidiary.
Market context
Sobi retains commercial rights to Empaveli, sold as Aspaveli, outside the United States. Biogen said a significant proportion of Apellis employees were expected to join it and that it aimed to fully de-lever by the end of 2027.
