Biogen Inc. Completes Acquisition of Apellis Pharmaceuticals via Merger and Tender Offer

Biogen Inc. has filed a final amendment to its Schedule 13D, marking an exit filing following the successful acquisition of Apellis Pharmaceuticals, Inc. On May 14, 2026, Biogen's wholly owned subsidiary, Aspen Purchaser Sub, Inc., completed a tender offer to acquire all outstanding shares of Apellis. The offer consisted of $41.00 per share in cash plus one contingent value right (CVR) worth up to $4.00 based on future milestones. Following the tender offer, the subsidiary merged with and into Apellis in accordance with Delaware law, resulting in Apellis becoming a wholly owned subsidiary of Biogen. Consequently, Biogen's direct beneficial ownership percentage has been reduced to 0.0% as the entity now holds 100% of the issuer through its subsidiary structure, and the previously established Tender and Support Agreement has been terminated. This filing serves as the formal conclusion of Biogen's reporting obligations under Schedule 13D for this transaction.