Biogen acquires Apellis Pharmaceuticals

Biogen has agreed to acquire Apellis Pharmaceuticals in a $5.6 billion cash deal, highlighting Biogen's strategy to enhance its presence in the immunology and rare disease sectors. This acquisition will provide Biogen with two marketed complement therapies, Syfovre and Empaveli, thereby expanding its capabilities in the treatment of immune-mediated conditions.

Under the terms of the agreement, Biogen will pay $41.00 per share in cash, representing an 86% premium to Apellis' 90-day volume-weighted average stock price and a 35% premium to its 52-week high. Additionally, Apellis shareholders will receive a contingent value right worth up to $4.00 per share, tied to Syfovre achieving specific global sales thresholds between 2027 and 2031. The transaction, which has received approval from both companies' boards, is anticipated to close in the second quarter of 2026. The acquisition will be financed through a combination of Biogen's cash reserves and new borrowings, with plans to repay the debt by the end of 2027.

The strategic acquisition of Apellis provides Biogen with Syfovre, the first approved treatment for geographic atrophy secondary to age-related macular degeneration, a retinal disease. The therapy demonstrated significant efficacy in clinical trials, reducing lesion growth by up to 36% with monthly treatment. Empaveli, the second therapy in the acquisition, is approved for several immune-mediated kidney conditions and adult paroxysmal nocturnal hemoglobinuria. These therapies generated a combined revenue of $689 million in 2025, with anticipated growth in the mid-to-high teens through 2028.

Biogen aims to leverage Apellis' established presence in nephrology to further its own pipeline, particularly benefiting its development of felzartamab, currently in Phase III trials for various kidney diseases. Apellis’ expertise and customer relationships in this area are expected to enhance Biogen’s readiness to commercialize forthcoming treatments.

The acquisition positions Biogen to compete more aggressively in the burgeoning immunology sector, enhancing its product offerings amid a landscape where innovation and targeted therapies are critical to growth. Looking forward, Biogen may need to navigate regulatory reviews and integrate Apellis' operations efficiently to capitalize on the deal's full potential.