Biogen Acquires Apellis for $5.3B and Advances Tau Drug, Shares Jump 10%
Biogen completed its $5.3B acquisition of Apellis Pharmaceuticals, adding marketed drugs SYFOVRE and EMPAVELI that generated $689M in 2025 and featuring $4.00-per-share CVRs tied to SYFOVRE revenue milestones. The company also advanced tau-targeting Alzheimer’s drug diranersen to late-stage trials after mid-stage data showed slowed disease progression, sending shares up 10%.
1. Apellis Acquisition Closed
Biogen closed its $5.3 billion acquisition of Apellis Pharmaceuticals by tendering $41.00 per share in cash and issuing a contingent value right per share. Approximately 82.4% of Apellis shareholders submitted stock, triggering an automatic exchange for remaining shares and delisting Apellis from Nasdaq.
2. Financial Outlook and CVRs
The addition of SYFOVRE and EMPAVELI, which generated $689 million in net revenue in 2025, is expected to be accretive to non-GAAP EPS in 2027. Contingent value rights could pay out up to $4.00 per share if SYFOVRE meets specific annual revenue benchmarks through 2031, and updated guidance will be provided with Q2 earnings.
3. Diranersen Advancement and Market Reaction
Following mid-stage trial results that showed slowed cognitive decline at all dose levels, Biogen advanced its tau-targeting Alzheimer’s candidate diranersen into late-stage trials. The news spurred a 10% rise in Biogen shares as investors weigh a potential shift from amyloid to tau therapies in Alzheimer’s treatment.