06:12 AM EST, 11/03/2025 (MT Newswires) -- Pfizer ( PFE ) said late Friday it filed a lawsuit against Metsera ( MTSR ) , its board of directors, and Novo Nordisk ( NVO ) , for allegedly breaching terms of its merger agreement with Metsera ( MTSR ).

Pfizer ( PFE ) said the lawsuit seeks to block Metsera ( MTSR ) from terminating the merger agreement and proceeding with an alternative proposal from Novo Nordisk ( NVO ), which Pfizer ( PFE ) claims cannot qualify as a "superior company proposal" under the deal terms due to significant regulatory risks.

Pfizer ( PFE ) said the US Federal Trade Commission already granted early termination of the waiting period under the Hart-Scott-Rodino Act for its pending Metsera ( MTSR ) acquisition and the transaction is "ready to complete" following Metsera's ( MTSR ) stockholder meeting on Nov. 13.

Pfizer ( PFE ) alleged that Novo Nordisk's ( NVO ) proposal is "an illegal attempt by a company with a dominant market position to suppress competition" and uses an unprecedented structure to evade antitrust review.

Metsera ( MTSR ) said in a separate press release it "disagrees with the allegations in Pfizer's ( PFE ) complaint and will address them in the Delaware Court of Chancery."

Metsera ( MTSR ) and Novo Nordisk ( NVO ) did not immediately respond to MT Newswires' request for comment.