Novo Nordisk bids $9 billion for Metsera, triggering Pfizer lawsuits

Novo Nordisk launched an unsolicited bid of about $9 billion for the obesity-focused biotech Metsera on October 30, 2025, challenging an acquisition Pfizer had already agreed to ^[1]. Pfizer has since filed two lawsuits in Delaware, and a judge was set to review the complaints on Tuesday, November 4 ^[2].

Pfizer agreed in September to pay up to $7.3 billion for Metsera — $4.9 billion upfront plus up to $2.4 billion in milestone payments — after a private bidding war with Novo that lasted months ^[1][2]. Metsera rejected Novo's offer six times, saying Novo already held a large share of the obesity market and could face antitrust scrutiny ^[2]. After Novo's top investor overhauled the company's board, Novo returned with the new unsolicited bid ^[2]. In a surprising move, Metsera said Novo's offer was superior and gave Pfizer until Tuesday to submit a higher bid ^[2].

Pfizer sued Metsera's board and Novo in Delaware's Court of Chancery on Friday, October 31, then filed a second, antitrust lawsuit in Delaware federal court on Monday, November 3 ^[2]. The state case was assigned to Vice Chancellor Morgan Zurn, who scheduled a hearing for Tuesday morning ^[2]. Pfizer's second complaint alleges Novo is using a 30-month "outside date" — the period before either party can terminate the merger — to delay Metsera's entry into the GLP-1 obesity drug market rather than to close a deal ^[2]. Pfizer said its own deal with Metsera had a nine-month timeline and received early termination of antitrust review on October 31 ^[2]. Pfizer also says Novo offered Metsera shareholders $6.5 billion upfront, before regulatory review, and tied the company to restrictive covenants that delay or prevent clinical progress ^[2].

Novo said it "closely adhered to all of the restrictions under the Pfizer merger agreement." "We are confident that the facts and the law are on our side," Novo said, calling Pfizer's suggestion that it would impair an emerging U.S. competitor "absurd and not based on facts, common sense, or market realities" ^[2]. Novo also said it would use its expertise "to accelerate the successful commercialisation of these assets to the benefit of patients in the U.S. and beyond" ^[2]. Metsera described Pfizer's allegations as "nonsense" and accused Pfizer of trying to drive down its takeover price and of gaming the schedule by not suing sooner, when it knew of Novo's bid on October 25 ^[2]. Pfizer's complaint included the line, "Something is clearly rotten in the state of Denmark" ^[2].

What is at stake is Metsera's lead drug candidate, MET-097i, a GLP-1 receptor agonist designed for monthly dosing instead of the weekly injections used by Novo's Wegovy and Ozempic and Eli Lilly's Zepbound and Mounjaro ^[1][2]. In the Phase IIb VESPER-1 trial, the highest dose tested, 1.2 mg, produced mean placebo-subtracted weight loss of 14.1% after 28 weeks, with some participants losing as much as 26.5% of their body weight ^[1]. Exploratory 36-week data showed continued weight loss with no plateau reached ^[1]. In the VESPER-3 trial of monthly dosing, participants who titrated to 1.2 mg reported a 13% increase in nausea and an 11% increase in vomiting compared with placebo ^[1]. Two of 239 participants, or 2.9%, discontinued treatment because of adverse events in VESPER-1, compared with discontinuation rates of up to 10% for other obesity medications ^[1]. Metsera says the drug requires 5 to 10 times lower doses than current GLP-1 options, which it says offers manufacturing and scalability advantages ^[1]. The company is on track to start Phase III trials in late 2025, with potential FDA approval projected for 2027 or 2028 ^[1].

Why it matters for patients

Metsera's drug is still experimental. It is not approved, and no one taking an obesity medication today would see a change in their prescription because of this bidding contest ^[1]. The practical question is timing. Pfizer argues that Novo ownership would delay the drug's arrival in the U.S. market, while Novo says it would speed commercialization ^[2]. Those are claims made in litigation, not findings by a court.

If MET-097i eventually reaches the market, its main selling point would be monthly rather than weekly injections, and lower doses that could ease manufacturing constraints that have limited supply of existing GLP-1 drugs ^[1][2]. Pfizer is betting on Metsera to enter an obesity market that some analysts forecast could reach $150 billion annually, and analysts say Metsera's therapies could generate $5 billion in sales ^[2]. Metsera shares fell 3.7% on Monday to close at $60.73; Pfizer shares ended flat, and Novo shares fell less than 1% ^[2].

What happens next

A Delaware judge was scheduled to hear the complaints on Tuesday, November 4 ^[2]. Metsera had given Pfizer until that day to submit a higher bid ^[2], and a Metsera shareholder meeting was scheduled for November 13, 2025, with Pfizer saying it could close shortly after that if it prevails ^[1]. Metsera's Phase III program is expected to begin in late 2025 ^[1].