Bengaluru/Wilmington, Del., U.S. – Pfizer (PFE.N) has filed a lawsuit against Metsera (MTSR.O) and Danish drugmaker Novo Nordisk (NOVOb.CO), claiming that Metsera violated its merger agreement by declaring Novo’s $8.5 billion bid as a superior offer. Pfizer is seeking a temporary restraining order to prevent Metsera from terminating their existing agreement, requesting that Metsera’s shareholder vote occur as planned on November 13, 2025.

The lawsuit comes shortly after Pfizer received early antitrust clearance from the U.S. Federal Trade Commission (FTC) for its proposed $7.3 billion acquisition of Metsera, with the Hart-Scott-Rodino waiting period waived ahead of the November 7 deadline.

“Pfizer’s claims against Novo Nordisk are meritless, and we will vigorously defend ourselves in any litigation,” said a spokesperson for Novo Nordisk. Metsera also stated it disagrees with Pfizer’s allegations and will address them in court.

Background: A Competitive Race for Metsera

Negotiations between Pfizer, Novo Nordisk, and Metsera began in early 2024. Novo Nordisk, maker of Wegovy and Ozempic, is attempting to regain ground in the obesity drug market after losing share to Eli Lilly (LLY.N). Metsera, meanwhile, is developing experimental therapies projected to generate up to $5 billion in sales.

Pfizer, which currently has no weight-loss drug, views the acquisition as a way to enter the $150 billion obesity market and offset declining COVID-related revenue and upcoming patent expirations. Pfizer claims Novo’s bid was structured to evade U.S. antitrust scrutiny, potentially suppressing competition.

Novo’s initial offer of $2 billion on January 23, 2025 was rejected by Metsera’s board due to regulatory risks and low valuation. Pfizer submitted a $30 per share non-binding proposal on June 2, followed by successive improved offers, which were initially rejected. By September, both Pfizer and Novo had submitted revised bids, with Pfizer alleging that Novo’s September 20 bid, including non-voting shares and dividends, was risky.

Antitrust and Foreign Investment Concerns

Pfizer’s complaint highlights potential pre-coordination between Metsera and Novo Nordisk before the public bid on October 25, possibly breaching the non-solicitation clause of the merger agreement. Pfizer emphasized its status as a leading U.S. company and raised concerns that a deal with foreign competitor Novo Nordisk could trigger scrutiny from the Committee on Foreign Investment in the United States (CFIUS), which reviews foreign acquisitions affecting national security.

Pfizer is seeking a court declaration that Novo’s bid is not a superior offer, along with damages and injunctive relief.