Company Announcement

Genmab ( GMAB ) to acquire Merus for USD 97.00 per share in an all-cash transaction representing a transaction value of approximately USD 8.0 billionProposed acquisition adds petosemtamab, a late-stage asset with two Breakthrough Therapy Designations, to Genmab’s portfolio Transaction anticipated to be accretive to EBITDA by end of 2029 Genmab ( GMAB ) to host a conference call today at 1:00 PM CEST / 12:00 PM BST / 7:00 AM EDT COPENHAGEN, Denmark; UTRECHT, The Netherlands; September 29, 2025, – Genmab A/S ( GMAB ) and Merus N.V. announced today that they have entered into a transaction agreement pursuant to which Genmab ( GMAB ) intends to acquire all the shares of Merus, a clinical-stage biotechnology company with its late-stage breakthrough therapy asset petosemtamab, which is in Phase 3 development, for USD 97.00 per share in an all-cash transaction representing a transaction value of approximately USD 8.0 billion. The transaction has been unanimously approved by the Boards of Directors of both companies. A wholly owned subsidiary of Genmab ( GMAB ) (“Purchaser”) will commence a tender offer for 100% of Merus’ common shares, which is anticipated to close by early in the first quarter of 2026.

The proposed acquisition of Merus is expected to meaningfully accelerate Genmab’s shift to a wholly owned model, expanding and diversifying the company’s revenue, driving sustained growth into the next decade and contributing to Genmab’s evolution into a biotechnology leader. The addition of petosemtamab, Merus’ lead asset, to Genmab’s promising 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.

“The proposed acquisition of Merus clearly aligns with our long-term strategy. It has the potential to significantly accelerate our evolution into a global biotechnology leader by providing durable growth for the company well into the next decade,” said Jan van de Winkel, Ph.D., President and Chief Executive Officer of Genmab ( GMAB ). “Petosemtamab has the potential to be a transformational therapy for patients living with head and neck cancer. With our proven track record of success, both in clinical development and in commercialization, we are confident that we will be able to unlock the promise of petosemtamab.”

“We are excited for the opportunity to join Genmab ( GMAB ), a leader in antibody therapeutics, to further develop and bring petosemtamab to patients. Our two companies have a rich history of innovation with multiple approvals in the field of multispecific antibodies. We believe Genmab ( GMAB ) has the right vision and experience to advance petosemtamab in recurrent/metastatic head and neck cancer and beyond,” said Bill Lundberg, M.D., President, Chief Executive Officer of Merus. “I’m immensely proud of the Merus team who have pioneered our foundational platform technologies to make better medicines and who have demonstrated - with an approved product and a product candidate, petosemtamab, in registrational studies - an ability to deliver on our promise to close in on cancer.”

Petosemtamab is an EGFRxLGR5 bispecific antibody with the potential to be both first- and best-in-class in head and neck cancer. It has been granted two Breakthrough Therapy Designations (BTD) by the U.S. Food and Drug Administration (FDA) for first- and second-line plus head and neck cancer indications. Of note, compelling Phase 2 data was presented at the American Society for Clinical Oncology (ASCO) 2025 Annual Meeting showing both 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. Based on Genmab’s experience in late-stage development and excellence in commercial execution, Genmab ( GMAB ) anticipates the potential for the initial launch of petosemtamab in 2027, subject to clinical results and regulatory approvals. 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 one-billion-dollar annual sales potential by 2029, with multi-billion-dollar annual revenue potential thereafter.

Details of the Transaction and Financing

Under the transaction agreement, Purchaser, a wholly owned subsidiary of Genmab ( GMAB ), will commence a tender offer for all the outstanding common shares of Merus. Following the closing of the tender offer, Merus and Genmab ( GMAB ) will effect a series of transactions resulting in Genmab ( GMAB ) owning 100% of the common shares of Merus (or a successor entity). Depending on the structure of the back end transactions, Merus shareholders that do not tender their shares into the tender offer will either receive the same consideration for their common shares as the common shares tendered into the tender offer (subject to applicable withholding taxes) or a fair price for their common shares determined by a Dutch court in statutory buy-out proceedings. The closing of the tender offer is subject to the satisfaction of customary closing conditions for similar transactions, including a minimum acceptance condition of at least 80% of Merus’ common shares (which threshold may be reduced to 75% unilaterally by Genmab ( GMAB ) if all other closing conditions are satisfied), approval by Merus’ shareholders of resolutions relating to Merus’ post-closing governance and the back end transactions at Merus’ extraordinary shareholders meeting to be held for that purpose, and completion of the relevant works councils consultation processes.

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

The transaction is not subject to a financing condition. Consideration is expected to be funded through a combination of cash on hand and approximately $5.5 billion of non-convertible debt financing. Genmab ( GMAB ) has obtained a funding commitment from Morgan Stanley Senior Funding, Inc. for this amount.

The financing package includes a meaningful portion of prepayable debt, in line with Genmab’s commitment to deleveraging with a target of gross leverage