Novo Nordisk agreed to acquire global rights to Omeros’ MASP-3 inhibitor zaltenibart in a deal worth up to $2.1 billion, marking a rapid strategic move into complement‑mediated rare diseases. Novo will pay roughly $340 million up front and near‑term milestones, and plans Phase 3 testing in paroxysmal nocturnal hemoglobinuria (PNH) while exploring kidney indications. Omeros had paused its Phase 3 ramp for financial reasons; Novo’s purchase restarts development and transfers global clinical responsibilities. The drug’s MASP‑3 mechanism targets the lectin pathway differently from existing C5 inhibitors, which could provide mechanistic advantages in intravascular and extravascular hemolysis if late‑stage trials confirm benefit. Investors reacted strongly: Omeros stock jumped on the announcement while Novo positions zaltenibart as a potential differentiated entrant in a crowded complement market dominated by Alexion/AstraZeneca and others. The deal underscores big pharma’s willingness to pay premium multiples for mid‑stage assets that could challenge established franchises.