Company: GNMSF
Filing Date: 2025-06-17
Form Type: 6-K
Source: 0001434265-25-000045
Chunk: 0

Company: GENMAB A/S
Filing Date: 2025-06-17
Form: 6-K
Chunk 0
---
### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549
<div align='center'>FORM 6-K</div>

<div align='center'>REPORT OF FOREIGN PRIVATE ISSUER PURSUANT TO RULE 13a-16 OR 15d-16</div>

#### OF THE SECURITIES EXCHANGE ACT OF 1934
<div align='center'>FOR THE MONTH OF JUNE 2025</div>

#### COMMISSION FILE NUMBER 001-38976

#### Genmab A/S
<div align='center'>(Exact name of Registrant as specified in its charter)</div>

#### Carl Jacobsens Vej 30

#### 2500 Valby

#### Denmark
<div align='center'>+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 be incorporated by reference in Genmab A/S’s registration statements on Form 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333-277273 and 333-284876 ) and to be a part thereof from the date on which this report is filed, to the extent not superseded by documents or reports subsequently filed or furnished.

### EXHIBIT INDEX
<div align='center'>SIGNATURE</div>

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: June 17, 2025