Novo Nordisk made a surprise unsolicited bid that values Metsera at roughly $9 billion, prompting Metsera’s board to deem the proposal “superior” to Pfizer’s earlier agreement and giving Pfizer four business days to respond. Novo structured the offer as a two-step transaction with $56.50 cash up front plus contingent value rights (CVRs) tied to clinical and regulatory milestones. Pfizer publicly condemned the move as “reckless and unprecedented,” signaling a likely legal and regulatory fight over the transaction. The counterbid thrust the obesity M&A race into open conflict between two global giants and highlights the strategic value placed on Metsera’s injectable GLP-1 and amylin programs slated for later-stage development. The tug-of-war creates immediate operational uncertainty for Metsera and may delay integration or trial execution as advisers, regulators and shareholders assess competing proposals. Antitrust scrutiny is now a material risk given both firms' positions in the obesity market. Deal specifics matter for payment timing and regulatory risk: Novo’s proposal pairs immediate cash with milestone CVRs up to $21.25 per share, shifting some execution risk onto future development success. For competitors and investors, the episode underscores how quickly strategic M&A dynamics in obesity can escalate and the potential for antitrust and litigation to reshape deal outcomes.