Company: GNMSF
Filing Date: 2025-10-31
Form Type: SC TO-T/A
Source: 0001193125-25-259490
Chunk: 3

Company: GENMAB A/S
Filing Date: 2025-10-31
Form: SC TO-T/A
Chunk 3
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 as follows (new text is indicated by bold, underlined textand deleted text is indicated by bold and stricken-through text ): Genmab and Purchaser have informed Merus that they or their affiliates have engaged, will engage or will continue to engage in discussions with certain executive officers of Merus with respect to potential employment and compensation arrangements to be effective following the SubsequentClosing Date, but no agreements or arrangements with respect to future employmenthave been entered into as of the date of this Offer to Purchase between Genmab or Purchaser, any of their respective affiliates and any such executive officers. If Dr. Lundberg resigns as President and Chief Executive Officer of Merus and Merus US, Inc. following the Closing, Genmab plans to have the Merus Board appoint Dr. van de Winkel to serve as President and Chief Executive Officer of Merus and Merus US, Inc. In addition, pursuant to the Transaction Agreement, Genmab and Purchaser have designated Anthony Pagano, Martine J. van Vugt, Ph.D. and Greg Mueller as non-executivedirectors of the Merus Board and Dr. van de Winkel as executive director of the Merus Board, each such designation to be effective upon the Closing and subject, in the case of the non-executivedirectors, to the adoption of the Governance Resolutions at the EGM or a Subsequent EGM.

SIGNATURES After due inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct. Date: October 31, 2025

| GENMAB HOLDING II B.V. |     |                                                    |
| BY:                    |     | /s/ Jan G. J. van de Winkel                        |
| Name:                  |     | Jan G. J. van de Winkel                            |
| Title:                 |     | Authorized Signatory                               |
| GENMAB A/S             |     |                                                    |
| BY:                    |     | /s/ Jan G. J. van de Winkel                        |
| Name:                  |     | Jan G. J. van de Winkel                            |
| Title:                 |     | President & Chief Executive Officer                |
| BY:                    |     | /s/ Anthony Pagano                                 |
| Name:                  |     | Anthony Pagano                                     |
| Title:                 |     | Executive Vice President & Chief Financial Officer |

EXHIBIT INDEX

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