Pfizer sued Metsera and Novo Nordisk in Delaware court seeking to stop Novo’s counter-offer to acquire obesity biotech Metsera, alleging breach of contract and an anticompetitive conspiracy. Pfizer claims the proposed tie-up would unlawfully eliminate a nascent U.S. competitor in the GLP-1 obesity market and asked the court for emergency relief to keep its merger agreement in place. Metsera called Pfizer’s claims “nonsense,” while the dispute exposes rising tensions as Big Pharma and obesity-drug leaders jockey for strategic assets. The litigation introduces a legal hurdle that could reshape the acquisition landscape for obesity-focused biotechs and signals intensified antitrust scrutiny when market concentration is at stake.