Biogen (BIIB) announced Thursday the completion of its acquisition of Apellis Pharmaceuticals, marking the end of Apellis as an independent publicly traded entity. Apellis shares have been delisted from the Nasdaq, and the company now operates as a wholly owned subsidiary of Biogen. The deal, valued at approximately $5.6 billion, positions Biogen to expand its rare-disease portfolio and enter the kidney disease market.
Under the terms of the acquisition, Apellis shareholders will receive $41 per share in cash. Additionally, they are entitled to a contingent value right (CVR) that could yield up to $4 per share if Syfovre achieves annual global net sales of $1.5 billion and $2.0 billion within specified timeframes. The tender offer closed on May 13, with approximately 105.7 million shares, or 82.4% of outstanding shares, tendered.
Biogen financed the deal in part through $2 billion in unsecured term loans, split into tranches maturing in 2027 and 2028. The company expects the acquisition to be accretive to adjusted earnings per share by 2027.
The acquisition brings two key commercial drugs into Biogen's rare-disease division: Syfovre, approved for geographic atrophy (GA) secondary to dry age-related macular degeneration, and Empaveli, a treatment for rare immune-mediated disorders. In 2025, these products generated combined net product revenue of $689 million.
A significant strategic benefit for Biogen is the expansion into kidney disease. Apellis provides a nephrology sales network and a late-stage therapy, felzartamab, which is in Phase 3 development for kidney diseases. First Phase 3 data for felzartamab is expected in the first half of 2027. Biogen CEO Christopher Viehbacher described the acquisition as a move to secure entry into the kidney disease space and establish a direct link to nephrologists.
BMO Capital analyst Evan Seigerman noted that the addition of Syfovre and Empaveli could meaningfully shift investor sentiment regarding Biogen's near-term revenue outlook, especially as the company contends with declining sales in its multiple sclerosis franchise. Biogen shares edged higher in early trading on Friday.
However, risks remain. The CVR milestones are not guaranteed, and Syfovre faces competition from Astellas' Izervay, which is already approved for GA in the U.S. The deal also reduces the number of publicly traded complement-focused drug developers, as Apellis centered its portfolio on the complement pathway.
Biogen plans to provide updated financial guidance in July with its second-quarter results, offering investors the first concrete look at Apellis's contribution post-close.
