Company: GNMSF
Filing Date: 2025-02-26
Form Type: 6-K
Source: 0001558370-25-001558
Chunk: 0

Company: GENMAB A/S
Filing Date: 2025-02-26
Form: 6-K
Chunk 0
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<div align='center'>UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER PURSUANT TO RULE 13a-16 OR 15d-16

OF THE SECURITIES EXCHANGE ACT OF 1934

FOR THE MONTH OF FEBRUARY 2025

COMMISSION FILE NUMBER 001-38976

Genmab A/S(Exact name of Registrant as specified in its charter)

Carl Jacobsens Vej 30

2500 Valby

Denmark

+45 70 20 27 28(Address of principal executive offices)</div>

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F.

<div align='center'>Form 20-F⌧Form 40-F◻</div>

This report on Form 6-K shall be deemed to beincorporated by referencein Genmab A/S’s registration statements onForm S-8(File No. 333-232693,333-253519, 333-262970, 333-277273 and 333-284876) and to be a part thereof from the date on which this report is filed, to the extent not superseded by documents or reports subsequently filed or furnished.

SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

| ​ | ​          | ​                                                         |
| ​ | GENMAB A/S |                                                           |
| ​ | ​          | ​                                                         |
| ​ | BY:        | /s/ Anthony Pagano                                        |
| ​ | ​          | Name: Anthony Pagano                                      |
| ​ | ​          | Title: Executive Vice President & Chief Financial Officer |

DATE: February 26, 2025

EXHIBIT INDEX

| ​​      |                         |
| Exhibit | Description of Exhibit  |
| ​       | ​                       |
| 3.1     | Articles of Association |
| ​       | ​                       |