NewAmsterdam Pharma Co N.V.

Item 5. Other Information.

(c)Rule 10b5-1 Trading Arrangements

On February 6, 2026, Ian Somaiya, our Chief Financial Officer terminated a Rule 10b5-1 trading arrangement intendedto satisfy the affirmative defense of Rule 10b5-1(c) that he initially adoptedon September 30, 2025 and that provided for the potential sale of up to 200,000 Ordinary Shares, subject to certain price thresholds and other conditions. 100,000 Ordinary Shares were sold under this arrangement prior to its termination. On March 27, 2026, Mr. Somaiya adopted a Rule 10b5-1 trading arrangement intended to satisfy the affirmative defense of Rule 10b5-1(c) providing for the potential sale of up to 200,000 Ordinary Shares, subject to certain price thresholds and other conditions. Thearrangement's expiration date is June 30, 2027.

On February 23, 2026, Louise Kooij, our Chief Accounting Officer, adopted a Rule 10b5-1 trading arrangement intended to satisfy the affirmative defense of Rule 10b5-1(c) providing for the potential sale of up to 210,000 Ordinary Shares, subject to certain price thresholds and other conditions. Thearrangement's expiration date is December 30, 2026.

On February 27, 2026, Michael Davidson, our Chief Executive Officer, terminated a Rule 10b5-1 trading arrangement intendedto satisfy the affirmative defense of Rule 10b5-1(c) that he initially adopted on September 29,

2025 and that provided for the potential sale of up to 750,000 Ordinary Shares, subject to certain price thresholds and other conditions. 306,293 Ordinary Shares were sold under this arrangement prior to its termination.

On March 31, 2026, Futurum B.V., an entity affiliated with John Kastelein, our Chief Scientific Officer, adopted a Rule 10b5-1 trading arrangement intended to satisfy the affirmative defense of Rule 10b5-1(c) providing for the potential sale of up to 250,000 Ordinary Shares, subject to certain price thresholds and other conditions. Thearrangement's expiration date is June 30, 2027.

Other than as discussed above, during the three months ended March 31, 2026, none of our directors or officers(as defined in Rule 16a-1(f) promulgated under the Exchange Act)adopted or terminated a Rule 10b5-1 trading arrangement (as defined in Item 408(a)(1)(i) of Regulation S-K) or a non-10b5-1 trading arrangement (as defined in Item 408(c) of Regulation S-K).