NewAmsterdam (NAMS) CSO Kastelein Sells 125K Shares After Option Exercise

What Happened

• Johannes J.J.P. Kastelein, Chief Scientific Officer and Director of NewAmsterdam Pharma (NAMS), exercised options to acquire 125,000 ordinary shares and sold those 125,000 shares in the open market on August 24, 2026. The weighted-average sale price was $26.91 per share for total proceeds of $3,363,750. The option exercise price was EUR 1.16392 per share (footnote F1).

Key Details

• Transaction date: August 24, 2026. Form filed August 25, 2026 (timely).
• Sale: 125,000 shares sold in multiple transactions at prices ranging from $26.72 to $27.70; weighted avg $26.91; proceeds $3,363,750 (F3).
• Exercise: 125,000-share option exercise reported; exercise price EUR 1.16392 (F1). The filing also shows a derivative conversion entry related to the exercise (reported as $0) (M code).
• Holdings/structure: Shares acquired on exercise were issued to Futurum B.V. through NAP PoolCo B.V. for the benefit of the reporting person; Kastelein reports sole voting and investment control over those securities (F2, F6). Filing notes 48,166 ordinary shares remain subject to RSU vesting (F4).
• Plan/authorization: Transactions executed pursuant to a Rule 10b5‑1 trading plan adopted by Futurum B.V. on March 31, 2026 (Remarks).
• Vesting/background: The option grant and vesting history are described in the footnotes (grant replaced an earlier award; portions vested immediately and the remainder vest over time) (F5).
• Filing timeliness: Report appears timely (filed the day after the transaction).

Context

• This was an option exercise followed by an immediate open‑market sale (effectively a cashless outcome): the insider exercised to acquire shares and then sold them. Sales are common for liquidity or tax/compensation purposes and do not by themselves indicate company outlook. The trading was executed under a pre-established 10b5‑1 plan, which typically structures timed sales in advance.