X0609 4 2026-09-30 0001936258 NewAmsterdam Pharma Co N.V. NAMS 0002000389 Kastelein Johannes Jacob Pieter true C/O NEWAMSTERDAM PHARMA COMPANY N.V. GOOIMEER 2-35 NAARDEN P7 1411 DC NETHERLANDS true true false false Chief Scientific Officer true Ordinary Shares 2026-09-30 4 M false 50246 A 119548 I See footnotes Ordinary Shares 2026-09-30 4 S false 50246 25.03 D 69302 I See footnotes Ordinary Shares 53500 D Option (right to buy) 2026-09-30 4 M false 50246 0 D 2031-07-06 Ordinary Shares 50246 344983 I See footnote The exercise price of the option is EUR 1.16392. These Ordinary Shares are held by Futurum B.V. ("Futurum") through NAP PoolCo B.V. ("PoolCo") for the benefit of the Reporting Person. The Reporting Person exercises sole voting and investment control over the securities held by Futurum through PoolCo. PoolCo has no voting or investment control or pecuniary interest in the securities held on behalf of Futurum. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $25.00 to $25.10 per share. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold in each transaction. Includes 48,166 ordinary shares subject to restricted stock unit awards that remain subject to vesting. The option was granted on November 22, 2022 to replace an option originally granted on July 6, 2021 which was cancelled in connection with the consummation of NewAmsterdam Pharma Company N.V.'s business combination with Frazier Lifesciences Acquisition Corporation. 292,214 of the shares underlying the option immediately vested on the grant date. 25% of the remaining shares underlying the option vested on January 1, 2021, the one-year anniversary of vesting start date, with the remaining shares vesting in equal monthly installments thereafter for three years, subject to the Reporting Person's continued service through each such date. The option was granted to and is held by Futurum through NAP PoolCo B.V. ("PoolCo") for the benefit of the Reporting Person. The Reporting Person exercises sole voting and investment control over the securities held by Futurum through PoolCo. PoolCo has no voting or investment control or pecuniary interest in the securities held on behalf of Futurum. Upon exercise of the option, the Ordinary Shares were issued to Futurum directly, pursuant to a written agreement among Futurum, PoolCo and the Issuer. Reported transactions executed pursuant to a Rule 10b5-1 trading plan adopted by Futurum B.V. on March 31, 2026. /s/ Michael Marino by Power of Attorney for Johannes Jacob Pieter Kastelein 2026-10-02