Biogen agreed to buy Apellis Pharmaceuticals in a deal valued at about $5.6 billion, using the combination to expand its immunology and rare-disease portfolio and accelerate pipeline execution. The acquisition is positioned as a direct fit with Biogen’s transformation strategy and its nephrology expansion plans. Biogen’s deal also links to Apellis’ commercialized assets, including pegcetacoplan products across complement-mediated indications. Reporting around the transaction highlights contingent-value structures tied to Syfovre performance milestones, signaling management attention to revenue scaling. The move comes amid prior Biogen restructuring, including earlier investment in immunology via the Human Immunology Biosciences acquisition, and is framed as near-term growth plus a platform for follow-on development assets. For the sector, the transaction reinforces that large cash-generating platforms are still willing to underwrite revenue-ready complement franchises, especially as investors reward M&A velocity over slower, asset-by-asset buildouts.