MTSR Shares Jump After Pfizer Merger Agreement

Metsera, Inc. (NASDAQ: MTSR) shares surged dramatically on Monday, September 22, 2025, following the announcement of a definitive merger agreement with pharmaceutical giant Pfizer Inc. (NYSE: PFE). The stock jumped over 62% to $53.99 as of 11:33 AM EDT, representing one of the most significant single-day gains in the biotechnology sector this year. The acquisition, valued at $4.9 billion initially with potential additional payments bringing the total to $7.3 billion, marks Pfizer’s strategic entry into the rapidly growing obesity treatment market through Metsera’s promising portfolio of next-generation incretin and amylin therapies.

Metsera Gains Momentum With Pfizer Partnership

Under the merger terms, Pfizer will acquire all outstanding Metsera shares for $47.50 per share in cash at closing, representing the initial $4.9 billion enterprise value. Additionally, shareholders will receive contingent value rights (CVRs) worth up to $22.50 per share tied to three key milestones: $5 per share for Phase 3 trial initiation of the MET-097i+MET-233i combination, $7 per share for FDA approval of monthly MET-097i monotherapy, and $10.50 per share for FDA approval of the combination therapy.

Metsera’s portfolio includes four clinical-stage programs targeting obesity and cardiometabolic diseases, with MET-097i as a weekly and monthly injectable GLP-1 receptor agonist in Phase 2 development, and MET-233i as a monthly amylin analog in Phase 1 trials. The company also has two oral GLP-1 receptor agonist candidates expected to begin clinical trials imminently. Recent Phase 1 results for MET-233i, presented at the European Association for the Study of Diabetes meeting, demonstrated a potentially best-in-class profile that caught Pfizer’s attention.

The transaction is expected to close in Q4 2025, subject to regulatory approvals and Metsera shareholder approval. For Pfizer, this acquisition represents a strategic pivot into the obesity market, leveraging the company’s extensive cardiometabolic experience and global manufacturing capabilities to accelerate development of what CEO Albert Bourla described as “potential best-in-class injectables” with differentiated efficacy, tolerability, and monthly dosing convenience.

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MTSR Stock Rockets on Heavy Trading Volume

MTSR shares opened at $52.59 and reached an intraday high of $54.46, representing a remarkable 62.06% gain from the previous close of $33.32. Trading volume exploded to over 10.3 million shares, more than seven times the average daily volume of 1.4 million shares. The stock’s 52-week range has expanded dramatically from a low of $12.30 to the current high of $54.46, reflecting the transformative nature of this acquisition.

The market capitalization jumped to $5.686 billion, with analysts maintaining an average price target of $63.50, suggesting potential upside even after the massive rally. Year-to-date returns for MTSR have reached an impressive 112.24%, vastly outperforming the S&P 500’s 13.50% gain over the same period. The company’s beta remains undefined due to its recent public listing, but the volatility pattern suggests high sensitivity to biotech sector developments and clinical trial outcomes.

Despite the company’s current lack of revenue and negative earnings of -$2.94 per share, investors are betting on the potential of Metsera’s obesity drug portfolio. The company maintains a strong balance sheet with $530.92 million in total cash and minimal debt, providing a solid foundation for continued research and development activities under Pfizer’s ownership.

Disclaimer: The author does not hold or have a position in any securities discussed in the article. All stock prices were quoted at the time of writing.