Biogen has agreed to acquire Apellis Pharmaceuticals in a transaction valued at approximately 5.6 billion dollars, strengthening its position in immunology and rare disease markets. The deal includes a cash offer of 41 dollars per share along with additional payments linked to future product performance.

The acquisition brings two marketed therapies into Biogen’s portfolio, including a treatment for geographic atrophy and another targeting rare kidney conditions. These medicines generated close to 700 million dollars in annual sales, offering Biogen an immediate revenue boost.

The move aligns with Biogen’s strategy to diversify beyond its core neurology business and expand into nephrology. It also provides commercial infrastructure to support upcoming pipeline assets, including late stage kidney disease programmes.

Biogen expects the acquisition to contribute to both short term growth and longer term revenue expansion, with projected double digit annual growth from the acquired products. The transaction is anticipated to close in the second quarter of 2026, subject to regulatory approvals.