Biogen Inc. will acquire Apellis Pharmaceuticals, Inc. for $41.00 per share in cash, totaling approximately $5.6 billion in upfront equity consideration. Apellis stockholders will also receive one contractual, non-transferable contingent value right (CVR) per share, potentially worth up to an additional $4.00 in cash. The CVR payments are contingent on SYFOVRE and related products achieving annual global net sales of at least $1.5 billion (for $2.00 per CVR) and $2.0 billion (for an additional $2.00 per CVR) in specified calendar years between 2027 and 2031. The acquisition includes two commercialized immunology medicines: EMPAVELI (for rare immune-mediated kidney diseases and PNH) and SYFOVRE (for geographic atrophy secondary to age-related macular degeneration). The transaction is expected to close in the second quarter of 2026, subject to successful completion of the tender offer, customary closing conditions, and regulatory approvals. Certain Apellis directors, executive officers, and a major stockholder (Morningside Venture Investments, Ltd.), collectively holding approximately 14% of outstanding shares, have agreed to tender their shares in the offer.