In response to Novo Nordisk’s unsolicited offer for Metsera last week, Pfizer has launched not one, but two lawsuits against the Danish drugmaker and the obesity biotech.
Last Thursday, Novo put in a surprise bid for Metsera, even though Pfizer had announced in September that it would acquire the biotech for $4.9 billion plus up to $2.4 billion in milestone payments.
Novo’s counteroffer included $6.5 billion in equity value for Metsera shareholders with an additional $2.5 billion tied to milestones, for a total potential value of about $9 billion.
Pfizer responded harshly to Novo’s proposal, describing it as “reckless and unprecedented,” and an “attempt by a company with a dominant market position to suppress competition in violation of law.”
The pharma giant also threatened legal action, a promise it has now fulfilled.
Pfizer’s first legal action came on October 31, 2025, with the company announcing it had filed a complaint in the Delaware Court of Chancery against Metsera, its board of directors and Novo Nordisk, alleging breach of the merger agreement between Pfizer and Metsera (as Metsera’s board had purportedly accepted Novo’s offer despite Pfizer’s agreement, calling it “superior”), and breach of fiduciary duty by Metsera’s directors in negotiating with Novo while under a lock-up with Pfizer.
Pfizer argued that Metsera’s labeling of Novo’s bid as a “superior proposal” violates the merger agreement, and asserted that Novo’s offer is not “reasonably likely to be completed” compared to Pfizer’s deal due to the substantial regulatory risks associated with it.
“Something is rotten in the state of Denmark,” Pfizer proclaimed in its complaint, referencing Shakespeare’s Hamlet as a dig at Pfizer’s motives.
In the statement about its first lawsuit, Pfizer said it “is taking this action to enforce and preserve its rights under the merger agreement. Metsera’s and its Directors’ actions, as well as those of Novo Nordisk, are in clear violation of their respective contractual and legal obligations. We are confident in the merits of our case and look forward to presenting it to the Court.”
Pfizer also explained that with respect to its pending acquisition of Metsera, the US Federal Trade Commission (FTC) granted early termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976.
Pfizer further asked for a temporary restraining order to block Metsera from terminating their deal.
With all necessary regulatory approvals now secured, Pfizer said it is prepared to finalize the transaction shortly after Metsera’s stockholder meeting on November 13.
Pfizer followed up with a second lawsuit yesterday. Filed in the District Court for the District of Delaware, the latest legal complaint targets antitrust and competition issues.
The complaint alleges Novo’s bid is an “illegal attempt… to suppress competition” by acquiring a promising US competitor. It also claims that Metsera’s controlling shareholders (including firms such as ARCH Venture Funds and Population Health Partners) colluded with Novo and Metsera to facilitate the scheme.
Related: Novo Nordisk Ignites High-Stakes Bidding War with Pfizer for Obesity Biotech Metsera
The latest lawsuit alleges that Novo’s bid “constitutes an anticompetitive action by Novo to protect its dominant market position in GLP-1s by capturing and killing a nascent American competitor before it gains the support of Pfizer, one of America’s leading pharmaceutical companies.”
Metsera issued a response on Monday, in which the biotech said Pfizer is “trying to litigate its way to buying Metsera for a lower price than Novo Nordisk.”
“Metsera’s Board of Directors will continue to stand firm on behalf of shareholders and patients,” the company explained in its statement. “Pfizer’s litigation arguments are nonsense, and Metsera will address them in court.”
The board of the biotech also filed a letter with the Delaware court asking the judge to deny Pfizer’s request for a hearing on the temporary restraining order to block its bid.
Metsera also claimed that Pfizer deliberately delayed taking legal action, saying the company was aware of Novo’s bid as early as October 25 but chose not to file suit until later.
The Pfizer-Metsera-Novo triangulation is shaping up to be one of the most high-profile pharma legal fights in years.
Pfizer and Novo are both at a significant crossroads, with Pfizer’s long-awaited return to obesity drugs at risk after earlier R&D setbacks, while Novo’s boldest move under new CEO Maziar “Mike” Doustdar follows cooling Wegovy growth, a planned ~9,000-person downsizing and the shutdown of its cell therapy R&D.
Both companies are vying for Metsera’s lead obesity candidates MET-097i, a Phase IIb injectable GLP-1 that could enable monthly dosing, plus a monthly amylin analog (a potential combo partner) and an oral GLP-1 designed to outperform small molecules while overcoming the scaling limits of other oral peptides.
While Novo is a pioneer in the GLP-1 obesity space with its semaglutide blockbusters Ozempic and Wegovy, Pfizer has been making attempts to carve out its own footprint in the space.
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