Biogen Inc. has announced its acquisition of Apellis Pharmaceuticals, Inc., a move that is set to significantly enhance its growth portfolio in immunology and rare diseases. The agreement, valued at approximately US$5.6 billion, will see Biogen purchase all outstanding shares of Apellis at US$41 per share in cash.
This price represents an 86% premium to the 90-day volume-weighted average stock price and a 35% premium to the 52-week high stock price. Additionally, Apellis shareholders will receive a contingent value right (CVR) for each share, entitling them to potential future payments based on the performance of SYFOVRE, one of Apellis’ key products.
The acquisition is expected to bolster Biogen’s near- and long-term growth prospects by adding two approved, high-potential products, SYFOVRE and EMPAVELI, to its portfolio. These products generated a combined revenue of US$689 million in 2025, with growth projected in the mid-to-high teens through 2028. The deal also aligns with Biogen’s strategy to expand its presence in nephrology, leveraging Apellis’ expertise and capabilities to strengthen its offerings in immune-mediated diseases.
Christopher A. Viehbacher, Biogen’s president and CEO, highlighted the strategic importance of the acquisition, stating that it complements Biogen’s existing portfolio and accelerates its transformation. He expressed confidence in the combined capabilities of the two companies to maximize the potential of SYFOVRE and EMPAVELI, while also welcoming Apellis’ employees to Biogen.
This acquisition underscores Biogen’s commitment to innovation and its focus on addressing unmet medical needs in immunology and rare diseases. The transaction is subject to customary closing conditions, including regulatory approvals, and is expected to be completed in the coming months.
