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Market overview

GLP-1 injections, the most famous of which you might recognise (the drug Ozempic ring a bell?), have taken the medical world by storm over the past few years. A bidding war between major players over acquiring one of these anti-obesity drugs, made for an eventful couple of weeks. In this article, we'll explore the circumstances surrounding the bidding war that culminated in Pfizer's acquisition of Metsera, as well as the implications of the acquisition itself. 

There are three big names in the development of GLP-1 (anti-obesity) drugs that are important to this case including:

• Metsera;
• Novo Nordisk (responsible for Ozempic); and
• Eli Lilly (responsible for the drug Mounjaro).

Analysts estimate the global obesity market could exceed $170 billion annually by the next decade, so getting a slice of this pie is something many in the space are looking into!

Pfizer: the acquirer

Of all the names in this article, Pfizer's might be the most recognisable given its covid-19 vaccine. A prominent American pharmaceutical company, its renowned for producing a diverse range of vaccines and medications.

Pfizer was developing an anti-obesity treatment called Danuglipron (don't ask me how to pronounce that). It failed in clinical trials this year, leaving it lagging behind Eli Lilly and Novo Nordisk – whose drugs have so far dominated this space (the former was recently valued at $1 trillion, the second company outside the technology sector to reach this number). Acquiring a biopharmaceutical company with a blockbuster weight-loss drug would support Pfizer's recovery in this market, allowing it to catch up with its competitors and raise the price of its shares – which are down more than half from its 2021 peak.

Metsera: the acquired

Enter Metsera – founded in 2022, this clinical-stage biopharmaceutical company specialised in developing obesity and metabolic disease treatments. It strove to create more convenient and effective treatments relative to those already on the market.

Importantly, Metsera went public this year, meaning it was listed on a stock market for the public to buy shares. This listing was described as among the largest biotech listings of 2025, demonstrating investor interest in obesity treatments.

Among other developments, Metsera's main offering is a GLP-1 injection called MET-097i. It's distinct from its competitors, Ozempic and Mounjaro, in two main ways. Firstly, instead of being injected once a week, patients only need to inject it once a month, making it more convenient. Secondly, clinical trials showed that using this injection resulted in 11.3% body mass reduction after 12 weeks – with limited gastrointestinal (ie, stomach-related) side effects. So, unlike its competitors, MET-097i not only requires less frequent doses, but each dose is also more tolerable for patients – though it’s worth noting the drug has yet to enter late-stage trials, meaning it's not fully done testing yet.

Novo Nordisk: the bidder

Novo Nordisk is a global healthcare company based in Denmark. The company specialises in diseases, such as diabetes, obesity, and rare endocrine and blood disorders.

It was the first on the GLP-1 scene with its offering, Wegovy – an umbrella term under which Ozempic falls. However, more recently, it’s faced some setbacks since other players, such as Eli Lilly, have begun dominating the market.

So, what's the deal? 

Pfizer closed its $10 billion acquisition of Metsera. The acquisition will help Pfizer gain a foothold in the rapidly growing weight-loss drug market, competing with giants like Eli Lilly as well as diversifying its portfolio.

However, it’s not the acquisition itself that makes this a big deal so much as the circumstances surrounding it and events leading up to it. I've compiled a chronological overview to help make the deal make more sense.

September 2025

Sometime before September, Novo Nordisk made a bid to acquire Metsera. Metsera refused this offer due to the “variety of risks” in its deal structure – remember, Metsera and Novo Nordisk are competitors in the same market, and a larger company acquiring a smaller one in the same market would raise competition concerns.

In September, Pfizer then announced that it would acquire Metsera. Upfront payments, paid immediately upon closing the deal, would amount to around $4.9 billion, but the acquisition could reach $7.3 billion with future payments. For context, future payments are a common feature of acquisition strategies and allow for the acquiring company (in this case Pfizer) to pay in instalments over time, sometimes depending on whether the acquired company (Metsera) meets certain financial performance targets.

The takeover was sealed – meaning it was finalised – so the terms of the offer would have been set by both companies, and the acquisition would have already been approved by a regulatory board to make sure there were no antitrust risks.

All this to say that the deal was well underway – that’s until October.

October 2025

Prompted by frustration over the rejection of its initial bid, which had been higher than Pfizer's, Novo Nordisk made an unsolicited bid to acquire Metsera.

It offered an upfront payment of $6.5 billion, but an overall sum of $9.1 billion including future payments.

Its offer, which was a thirty-month contract, also had a unique two-step share structure which would first allow Metsera shareholders to be paid the majority of the deal value (the $6.5 billion) before full regulatory approval. This meant that even if the deal didn't go through, Metsera shareholders would still be paid the majority of the amount. In exchange, Novo Nordisk would receive 50% of Metsera's non-voting shares.

Importantly, this first step was also bound to a contractual promise making it more expensive and difficult for any other company to acquire Metsera within the contract's thirty-month period, even if the deal fell through due to regulatory concerns.  

Upon receiving regulatory clearance, the second step of the deal would then take place: Novo Nordisk would pay for the remaining shares depending on Metsera's financial performance (another example of future payments, as we discussed earlier).

To make matters worse for Pfizer, Metsera then released a statement notifying Pfizer that Novo Nordisk's offer was a "superior company proposal". This triggered a four-day window for Pfizer to counter the offer.

On October 31, Pfizer filed its first lawsuit against Metsera and Novo Nordisk on the basis of breach of contract. It alleged that Metsera had broken its merger agreement with Pfizer, and pointed out that Novo's proposal couldn’t be considered "superior" because of its high regulatory risk. Pfizer's offer, on the other hand, provided a lower-risk and safer alternative for Metsera, making it more appealing.

At this point, if I were Metsera, I'd be feeling like the belle of the ball.

November 2025

A few days after launching its first lawsuit, Pfizer filed a second lawsuit against both Metsera and Novo Nordisk, which centered on the allegation that Novo Nordisk's bid was an anticompetitive action. Novo Nordisk's proposed acquisition sought to protect its dominant position in the anti-obesity market, by eliminating a smaller competitor, which – Pfizer pointed out – entailed "capturing and killing a nascent American competitor before it gains the support of Pfizer, one of America's leading pharmaceutical companies".

On 5 November, two things happened. First, the US Federal Trade Commission (FTC), the national agency promoting market competition and enforcing antitrust laws, warned Novo Nordisk that its proposed offer may violate national merger laws. Secondly, a judge in the courts where Pfizer's lawsuits were filed blocked a restraining order requested by Pfizer as an attempt to halt Novo Nordisk's deal.

Subsequently, Pfizer countered Novo Nordisk's bid with a higher offer amounting to almost double the initial September offer – now at $10 billion.

On November 13, Pfizer's offer was accepted. Two lawsuits and one unsolicited bid later, we're back where we started: Metsera is now officially wholly owned by Pfizer.

What does this mean for…

Pfizer?  

• Expanding its portfolio: the acquisition of Metsera will allow Pfizer to expand its offering beyond its weakening covid-19 offering. 
• Expanding into the anti-obesity drug market: Metsera's MET-097i – distinct from competitors' injections in that it only needs to be taken monthly, not weekly, and has less extreme side effects – provides Pfizer with an opportunity to successfully re-enter, and possibly take over, the obesity market. This market is highly lucrative and competitive, estimated to reach a valuation of $100 billion by 2030.
• Revenue concerns: on the other hand, as Metsera's MET-097i injection is still expected to undergo late-stage clinical development and manufacturing, it’s not expected to launch until 2028 to 2029. Pfizer is anticipating revenue hits from some of its other drugs losing its patent protection between 2026 to 2028, so if Metsera's drug is successful, it could help offset these losses.
• Risk of failure: with great promise comes great risk. MET-097i has a lot of potential, but it's not yet reached late-stage clinical trials. If it fails, there's a chance Pfizer may have overpaid for this acquisition – a fact that, in light of its bidding war with Novo Nordisk, is especially disappointing.

Other pharmaceuticals?

• Regulatory awareness: the lawsuits surrounding this acquisition, combined with the FTC's involvement, may signal increased regulatory involvement in mergers & acquisitions (M&A) activity in the pharmaceutical space going forward.

The market?

• Share prices: after the acquisition was sealed, the value of Pfizer's shares went up. This typically means that more people are buying shares in the company, driving up demand and therefore value, and indicates that the company is performing well and that its future outlooks are positive. By contrast, Novo Nordisk's share price went down, indicating the opposite.
• Encouraged investment in biotechnology: the deal demonstrates the commercial potential of weight-loss drugs – reinforced by the fact that several venture funds who initially invested in Metsera are set to make large returns from the sale. This could encourage more biotech investment and greater M&A activity in this sector.
• Increased competition in the market: current market leaders, Eli Lilly and Novo Nordisk, can't get too comfortable with its offerings. Pfizer's entry with a potentially distinct asset – the MET-097i injection – increases competitive pressure between the three players, setting the stage for greater innovation in the GLP-1 space. 

When do the lawyers come in?

This case is a great example of a deal involving many different practice areas. Of course, we get to see corporate law in action in the form of the acquisition itself – for which corporate M&A lawyers will have been hard at work reviewing contracts, researching its client's market, conducting due diligence and necessary checks to ensure all is clear. During this process, tax lawyers would have likely also advised on the tax implications of the acquisitions and structured them for tax efficiency, capital markets lawyers would have navigated the regulatory and transactional aspects of the acquisition and advised on the legal structuring of the deal, and competition lawyers would’ve provided advice on the antitrust implications of the acquisition.

However, this was no ordinary acquisition. Designing the share structures that were proposed in both Pfizer and Novo Nordisk's bids would’ve entailed further advice from a similar range of teams, most notably corporate lawyers with expertise in structuring a merger agreement.

As we've seen, this case also involved not one but two lawsuits: the first over breach of contract and the second over competition law issues. This is where commercial litigation teams, who handle commercial disputes (like this one), or competition lawyers, who specialise in laws that regulate fair competition in the marketplace and advise on whether mergers and acquisitions comply with competition regulations, would step in.

All in all, Pfizer's acquisition(s) of Metsera made for a very legally active deal, with lots of overlapping challenges. Whether you're applying to firms that work with biopharmaceutical clients or interested in building your understanding of corporate M&A more generally, I hope this article provided a fun insight into the overlapping challenges, legal and commercial, posed by high-stakes acquisitions.