Genmab A/S ( GMAB ) on Monday agreed to acquire Merus N.V ( MRUS ). with its late-stage asset petosemtamab, which is in Phase 3 development, for $97 per share in an all-cash transaction representing a transaction value of approximately $8 billion.

The transaction is anticipated to close by early in the first quarter of 2026.

The proposed acquisition of Merus is expected to accelerate Genmab’s shift to a wholly owned model, expanding and diversifying the company’s revenue, driving sustained growth into the next decade.

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Adding petosemtamab, Merus’ lead asset, to Genmab’s late-stage pipeline is a compelling strategic fit with Genmab’s portfolio and aligns with Genmab’s expertise in antibody therapy development and commercialization in oncology.

Following the closing of the transaction, Genmab ( GMAB ) will have four proprietary programs expected to drive multiple new drug launches by 2027.

Petosemtamab is an EGFRxLGR5 bispecific antibody with the potential to be both first- and best-in-class in head and neck cancer. Phase 2 data was presented at the American Society for Clinical Oncology 2025 Annual Meeting showing an overall response rate and median progression free survival that were substantially higher than standard of care.

Merus is currently running two Phase 3 trials in first- and second/third-line head and neck cancer, with topline interim readout of one or both trials anticipated in 2026.

Genmab ( GMAB ) anticipates the potential for the initial launch of petosemtamab in 2027. Genmab ( GMAB ) also intends to broaden and accelerate petosemtamab’s development with potential expansion into earlier lines of therapy.

Following its initial anticipated approval, Genmab ( GMAB ) believes that petosemtamab will be accretive to EBITDA with at least $1 billion annual sales potential by 2029, with multi-billion-dollar annual revenue potential thereafter.

The $97.00 per share purchase price represents a premium of approximately 41% over Merus’ closing stock price on September 26, 2025, of $68.89 and approximately 44% over Merus’ 30-day volume weighted average price of $67.42.

Consideration is expected to be funded through cash and approximately $5.5 billion of non-convertible debt financing.

William Blair views this deal as positive for Genmab ( GMAB ), as it adds an asset with peak sales of $3 billion to $4 billion in head and neck cancer alone.

Analyst Matt Phipps said, “While this deal is larger than we had expected for Genmab ( GMAB ), we view the opportunistic acquisition positively, as it adds to several other late-stage or approved programs that can drive significant revenue growth in the 2030s, surpassing the revenue peaks from royalties of Darzalex.”

For Merus, William Blair had expected an acquisition eventually, likely after initial Phase 3 results in 2026. Investors will now focus on how the pending Phase 2 colorectal cancer (CRC) data factored into the decision to sell early, as strong results might have supported a higher premium.

Price Action: MRUS stock is up 37.16% at $94.49, and GMAB stock is down 2.20% at $28.43 at last check Monday.

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