Biogen Inc. (Parent) will acquire Apellis Pharmaceuticals, Inc. (Company) through a tender offer and subsequent merger. The offer price is $41.00 per share in cash, plus one contractual, non-transferable contingent value right (CVR) per share, potentially adding up to $4.00 in cash. The upfront equity consideration for the acquisition is approximately $5.6 billion. The offer price represents an 86% premium to Apellis's 90-day volume-weighted average stock price and a 35% premium to its 52-week high. CVRs 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 is expected to close in the second quarter of 2026, subject to customary closing conditions and regulatory approvals. Apellis's key commercialized products, EMPAVELI and SYFOVRE, generated combined net sales of $689 million in 2025 and are expected to grow at a mid-to-high teens rate through at least 2028. Certain Apellis directors and executive officers, holding approximately 14% of outstanding shares, have entered into a Tender and Support Agreement to tender their shares.