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NewAmsterdam Pharma (NAMS) CSO exercises options, sells 125K shares

(Neutral)
(Neutral)
Form Type
4

Rhea-AI Filing Summary

NewAmsterdam Pharma Co N.V. (NAMS) reports that Chief Scientific Officer Johannes Jacob Pieter Kastelein, through Futurum B.V. and NAP PoolCo B.V., exercised options for 125,000 Ordinary Shares and on the same day sold 125,000 Ordinary Shares at a weighted average price of $26.91 per share. The options had an exercise price of EUR 1.16392 per share and were held indirectly through Futurum/PoolCo. After these transactions, Kastelein continues to hold 395,229 options indirectly and 53,500 Ordinary Shares directly, including 48,166 shares subject to RSU vesting. All reported trades were executed under a Rule 10b5-1 trading plan adopted by Futurum B.V. on March 31, 2026.

Positive

  • None.

Negative

  • None.
Insider Kastelein Johannes Jacob Pieter
Role Chief Scientific Officer
Sold 125,000 shs ($3.36M)
Approx. gross sale proceeds $3.36M
Type Security Shares Price Value
Exercise Option (right to buy) F1, F5, F6 125,000 $0.00 $0.00
Exercise Ordinary Shares F1, F2 125,000 -- --
Sale Ordinary Shares F3, F2 125,000 $26.91 $3.36M
holding Ordinary Shares F4 -- -- --
Holdings After Transaction: Option (right to buy) — 395,229 shares (Indirect, See footnote); Ordinary Shares — 69,302 shares (Indirect, See footnotes); Ordinary Shares — 53,500 shares (Direct)
Footnotes (6)
  1. F1. The exercise price of the option is EUR 1.16392.
  2. F2. 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.
  3. F3. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $26.72 to $27.70 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.
  4. F4. Includes 48,166 ordinary shares subject to restricted stock unit awards that remain subject to vesting.
  5. F5. 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.
  6. F6. The option was granted to and is held by Futurum through 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.
Options Exercised 125,000 options Options exercised into Ordinary Shares on August 24, 2026
Shares Sold 125,000 Ordinary Shares Shares sold on August 24, 2026 after option exercise
Weighted Average Sale Price $26.91 per share Weighted average price for 125,000 Ordinary Shares sold
Sale Price Range $26.72–$27.70 per share Range of prices for multiple sale transactions
Option Exercise Price EUR 1.16392 per share Exercise price of the option converted into Ordinary Shares
Options Held After Transaction 395,229 options Indirectly held options following the August 24, 2026 exercise
Direct Ordinary Shares Held 53,500 shares Direct holdings after the reported transactions
RSU Shares Subject to Vesting 48,166 shares Ordinary Shares subject to restricted stock unit awards
Rule 10b5-1 trading plan regulatory
"Reported transactions executed pursuant to a Rule 10b5-1 trading plan"
A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.
weighted average price financial
"The price reported in Column 4 is a weighted average price."
Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.
restricted stock unit awards financial
"Includes 48,166 ordinary shares subject to restricted stock unit awards"
Restricted stock unit awards are company promises to deliver a specific number of shares to employees or service providers in the future once conditions—such as staying with the company for a set time or meeting performance targets—are met. They matter to investors because when the promises convert into actual shares they increase the total share count and can reduce earnings per share, while also aligning recipients’ interests with stock performance much like deferred pay that turns into ownership if goals are met.
pecuniary interest financial
"PoolCo has no voting or investment control or pecuniary interest"
indirect ownership financial
"These Ordinary Shares are held by Futurum B.V. through NAP PoolCo B.V."

FAQ

What transactions did NAMS insider Johannes Kastelein report on this Form 4?

Johannes Kastelein reported exercising options for 125,000 Ordinary Shares and selling 125,000 Ordinary Shares of NewAmsterdam Pharma Co N.V. on August 24, 2026, all held indirectly through Futurum B.V. and NAP PoolCo B.V.

At what prices did the NAMS Form 4 transactions occur?

The options had an exercise price of EUR 1.16392 per share. The 125,000 Ordinary Shares sold were at a weighted average price of $26.91 per share, with individual trades ranging from $26.72 to $27.70 per share.

How many NAMS securities does Johannes Kastelein hold after these transactions?

After the reported transactions, Johannes Kastelein holds 395,229 options indirectly through Futurum B.V./NAP PoolCo B.V. and 53,500 Ordinary Shares directly, which include 48,166 shares subject to restricted stock unit vesting.

Were the August 24, 2026 NAMS trades made under a Rule 10b5-1 plan?

Yes. The Form 4 states that the reported transactions were executed pursuant to a Rule 10b5-1 trading plan adopted by Futurum B.V. on March 31, 2026.

Who actually holds the NAMS shares involved in the Form 4 transactions?

The exercised option and sold shares are held indirectly by Futurum B.V. through NAP PoolCo B.V. for the benefit of Johannes Kastelein. He has sole voting and investment control over these securities; PoolCo has no voting, investment control, or pecuniary interest.

What portion of Kastelein’s NAMS holdings are unvested RSUs?

Of the 53,500 Ordinary Shares held directly by Johannes Kastelein, 48,166 shares are described as ordinary shares subject to restricted stock unit awards that remain subject to vesting.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Learn about SEC filing dates
SEC Form 4
FORM 4UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940
OMB APPROVAL
OMB Number:3235-0287
Estimated average burden
hours per response:0.5
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
X
Check this box to indicate that a 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). See Instruction 10.
1. Name and Address of Reporting Person*
Kastelein Johannes Jacob Pieter

(Last)(First)(Middle)
C/O NEWAMSTERDAM PHARMA COMPANY N.V.
GOOIMEER 2-35

(Street)
NAARDEN1411 DC

(City)(State)(Zip)

NETHERLANDS

(Country)
2. Issuer Name and Ticker or Trading Symbol
NewAmsterdam Pharma Co N.V. [ NAMS ]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
XDirector10% Owner
XOfficer (give title below)Other (specify below)
Chief Scientific Officer
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
08/24/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm filed by One Reporting Person
Form filed by More than One Reporting Person
4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year)2A. Deemed Execution Date, if any (Month/Day/Year)3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4)
CodeVAmount(A) or (D)Price
Ordinary Shares08/24/2026M125,000A(1)194,302ISee footnotes(2)
Ordinary Shares08/24/2026S125,000D$26.91(3)69,302ISee footnotes(2)
Ordinary Shares53,500(4)D
Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year)3A. Deemed Execution Date, if any (Month/Day/Year)4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 6. Date Exercisable and Expiration Date (Month/Day/Year)7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Option (right to buy)(1)08/24/2026M125,000 (5)07/06/2031Ordinary Shares125,000$0.00395,229ISee footnote(6)
Explanation of Responses:
1. The exercise price of the option is EUR 1.16392.
2. 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.
3. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $26.72 to $27.70 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.
4. Includes 48,166 ordinary shares subject to restricted stock unit awards that remain subject to vesting.
5. 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.
6. The option was granted to and is held by Futurum through 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.
Remarks:
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 Kastelein08/25/2026
** Signature of Reporting PersonDate
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)