Biogen announced it has entered into a definitive agreement to acquire Apellis Pharmaceuticals for approximately $5.6 billion in cash, marking a strategic move to strengthen its presence in immunology, rare disease, and nephrology. The transaction includes a purchase price of $41 per share along with contingent value rights tied to future sales performance of SYFOVRE.
The acquisition brings two commercial-stage therapies, EMPAVELI and SYFOVRE, into Biogen’s portfolio. These treatments generated a combined $689 million in net product revenue in 2025 and are expected to grow at a mid-to-high teens rate through at least 2028. EMPAVELI is approved for rare kidney diseases and paroxysmal nocturnal hemoglobinuria, while SYFOVRE is the first approved therapy for geographic atrophy, an advanced form of age-related macular degeneration.
Biogen said the deal will enhance its near- and long-term growth outlook by adding immediate revenue-generating products with significant expansion potential. The company also expects to leverage Apellis’ commercial infrastructure and expertise to accelerate its entry into nephrology and support the development and future launch of felzartamab, its Phase 3 kidney disease candidate.
The transaction is expected to close in the second quarter of 2026, subject to customary conditions and regulatory approvals. Biogen plans to finance the deal through a combination of cash and borrowings and expects to fully deleverage by the end of 2027.
Financially, the acquisition is expected to be increasingly accretive to Biogen’s non-GAAP diluted earnings per share starting in 2027 and to meaningfully boost its EPS compounded annual growth rate through the end of the decade.
The agreement also includes milestone-based payments through contingent value rights. Apellis shareholders may receive additional payments if SYFOVRE achieves certain global net sales thresholds between 2027 and 2031.
Biogen noted that the acquisition aligns with its strategy of adding de-risked, commercial-stage assets that can contribute to growth ahead of its internal pipeline, which is expected to drive more significant revenue starting later in the decade.
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“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. We look forward to welcoming Apellis employees to Biogen. We believe our combined capabilities and experience will allow us to maximize the potential of SYFOVRE and EMPAVELI, while Apellis’ talent, expertise and field capabilities will further strengthen Biogen, deepening the foundation for our growing nephrology franchise with felzartamab and serving many more patients with immune-mediated retinal disease.”
Christopher A. Viehbacher, President And Chief Executive Officer, Biogen
“I am incredibly proud of the Apellis team and what we have achieved, including bringing two transformational medicines – SYFOVRE and EMPAVELI – to patients and building an innovative pipeline leveraging our deep expertise in complement science. With Biogen’s extensive experience with immunology and rare disease, we believe this transaction will accelerate our impact and enable us to reach more patients. This transaction represents a compelling outcome for our shareholders and a strong validation of our strategy, scientific innovation, and execution.”
Cedric Francois, M.D., Ph.D., Co-Founder And Chief Executive Officer, Apellis Pharmaceuticals
