Johannes Jacob Pieter Kastelein - 05 Jan 2026 Form 4 Insider Report for NewAmsterdam Pharma Co N.V. (NAMS)

Role
Chief Scientific Officer, Director
Signature
/s/ Louise Kooij by Power of Attorney from Johannes Jacob Pieter Kastelein
Issuer symbol
NAMS
Transactions as of
05 Jan 2026
Net transactions value
-$199,500
Form type
4
Filing time
07 Jan 2026, 18:31:26 UTC
Previous filing
25 Aug 2025
Next filing
24 Feb 2026
SEC
View on sec.gov

Reporting Owners (1)

Name Relationship Address Signature Signature date CIK
Kastelein Johannes Jacob Pieter Chief Scientific Officer, Director C/O NEWAMSTERDAM PHARMA COMPANY N.V., GOOIMEER 2-35, NAARDEN, NETHERLANDS /s/ Louise Kooij by Power of Attorney from Johannes Jacob Pieter Kastelein 07 Jan 2026 0002000389

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
transaction NAMS Ordinary Shares Sale $199,500 -6,000 -7.5% $33.25 73,481 05 Jan 2026 Direct F1, F2
transaction NAMS Ordinary Shares Award +25,500 +35% 98,981 07 Jan 2026 Direct F3, F4

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Underlying Class Amount Exercise Price Ownership Footnotes
transaction NAMS Option (right to buy) Award $0 +115,000 $0.000000 115,000 07 Jan 2026 Ordinary Shares 115,000 $35.45 Direct F5
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Buy Plan / Sale Plan: These are also open market purchases/sales of shares, but in this case the transaction is part of a trading plan. Rule 10b5-1 allows insiders to setup a trading plan to buy/sell stocks over a certain period of time. Since the purchases/sales are predetermined, this protects the insiders from violating insider trading law.

Transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

Explanation of Responses:

Id Content
F1 Represents pre-arranged sale of shares by the Reporting Person solely to cover tax withholding obligations in connection with the vesting and settlement of restricted stock units (RSUs) pursuant to sell-to-cover agreement entered into with the Issuer. The sale does not represent a discretionary transaction by the Reporting Person.
F2 The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $32.77 to $33.58 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.
F3 Represents RSUs, each representing a contingent right to receive one ordinary share. 1/3 of the RSUs will vest on each of the first, second and third anniversaries of the vesting start date, subject to the Reporting Person's continued service through each such date.
F4 Each RSU was granted on January 7, 2026 for no consideration.
F5 25% of the shares underlying the option will vest on Janaury 2, 2027, the one-year anniversary of the 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.