Biogen Acquires Apellis Pharmaceuticals for $5.6 Billion

On March 31, 2026, Biogen Inc. announced its agreement to acquire Apellis Pharmaceuticals Inc. for approximately $5.6 billion in cash. The deal, which is one of Biogen's largest acquisitions to date, involves a purchase price of $41 per share, representing a 140% premium over Apellis' last closing price. This strategic move aims to enhance Biogen's portfolio in immunology and rare diseases, particularly as it seeks to diversify beyond its declining multiple sclerosis franchise.

Biogen Acquires Apellis Pharmaceuticals (APLS) for $5.6B in Major Rare Disease PlayBloombergCNBC

Biogen's acquisition of Apellis is driven by the need for new growth avenues as revenue from its multiple sclerosis drugs wanes. The deal provides Biogen access to two approved drugs: Empaveli, which treats rare kidney diseases and a blood disorder, and Syfovre, approved for geographic atrophy, a leading cause of blindness. Together, these products generated approximately $689 million in sales in 2025 and are projected to grow at a mid-to-high teens percentage rate through 2028.

CNBCBloombergFiercePharmaApellis Pharmaceuticals Jumps as Biogen Agrees $5.6 Billion Buyout

Biogen CEO Chris Viehbacher emphasized the strategic fit of Apellis within Biogen's broader goals, stating, “We see this as being very synergistic with where our future pipeline is going to go.” The acquisition is expected to bolster Biogen's capabilities in nephrology, particularly as it prepares for the Phase 3 trials of its own kidney drug, felzartamab, anticipated to yield results in the first half of 2027.

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To finance the acquisition, Biogen plans to utilize a combination of cash and borrowings, with an aim to fully deleverage by the end of 2027. Analysts have noted that while the acquisition could provide a much-needed boost to Biogen's earnings, concerns remain regarding the premium paid for Apellis and the initial uptake of Syfovre, which has faced mixed feedback from healthcare professionals.

Reuters

Following the announcement, Apellis' stock surged by over 136% in pre-market trading, reflecting investor optimism about the acquisition. Conversely, Biogen's shares fell nearly 5%, a common market reaction when a company pays a significant premium for an acquisition. This decline highlights the immediate financial pressures that large-scale cash acquisitions can impose on the acquiring company.

Biogen Acquires Apellis Pharmaceuticals (APLS) for $5.6B in Major Rare Disease PlayApellis Pharmaceuticals Jumps as Biogen Agrees $5.6 Billion BuyoutReuters

Despite the strategic advantages, some analysts have expressed skepticism regarding the sustainability of Syfovre's growth, citing disappointing initial uptake and competition from other treatments, such as Astellas Pharma's Izervay. RBC Capital Markets analyst Brian Abrahams noted, “We believe there are still considerable commercial uncertainties around growth and sustainability.”

Bloomberg

Biogen's acquisition of Apellis Pharmaceuticals marks a significant step in its strategic pivot towards immunology and rare diseases. While the deal is poised to enhance Biogen's product offerings and revenue potential, it also introduces challenges related to market competition and the financial implications of the acquisition. The transaction is expected to close in the second quarter of 2026, pending regulatory approvals and shareholder consent.

Biogen Acquires Apellis Pharmaceuticals (APLS) for $5.6B in Major Rare Disease Play