NewAmsterdam Pharma affiliate plans 250K-share sale

NewAmsterdam Pharma Co N.V.

Rhea-AI Filing Summary

NewAmsterdam Pharma Co N.V. (NAMS) is the issuer of ordinary shares that an affiliate, for the account of Kastelein Johannes Jacob Pieter, plans to sell under Rule 144. A notice covers up to 250,000 ordinary shares, with J.P. Morgan Securities LLC acting as broker on Nasdaq.

The filing states these shares are expected to be sold in the next 90 days by Futurum B.V., where John Kastelein is a director. The shares relate to an option exercise from the issuer on 08/24/2026, for cash consideration. Reported outstanding ordinary shares total 119,537,169.

Key Figures

Ordinary shares to be sold: 250,000 shares Aggregate market value of shares to be sold: 6,967,500 Ordinary shares outstanding: 119,537,169 shares +2 more

5 metrics

Ordinary shares to be sold 250,000 shares Maximum number of NewAmsterdam Pharma ordinary shares covered by the Rule 144 notice

Aggregate market value of shares to be sold 6,967,500 Aggregate market value reported for the 250,000 ordinary shares

Ordinary shares outstanding 119,537,169 shares Ordinary shares of NewAmsterdam Pharma Co N.V. reported as outstanding

Planned sale window 90 days Shares expected to be sold in the next 90 days from the 08/24/2026 notice

Option exercise date 08/24/2026 Date of option exercise through which the securities to be sold were acquired

Key Terms

Rule 144, affiliate, ordinary shares, option exercise

4 terms

Rule 144 regulatory

"See the definition of "person" in paragraph (a) of Rule 144."

Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.

affiliate regulatory

"Affiliate"

ordinary shares financial

"Ordinary Shares | J.P. Morgan Securities LLC"

Ordinary shares are a type of ownership stake in a company, giving shareholders a right to participate in the company’s profits and decision-making through voting. They are similar to owning a piece of a business, and their value can rise or fall based on the company's performance. Investors buy ordinary shares to potentially earn dividends and benefit from the company's growth over time.

option exercise financial

"Option Exercise | Issuer | | | 250000 | 08/24/2026 | Cash"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What share sale is being reported for NewAmsterdam Pharma Co N.V. (NAMS) in this Form 144/A?

The notice covers a proposed sale of up to 250,000 ordinary shares of NewAmsterdam Pharma Co N.V. These shares are to be sold on behalf of Kastelein Johannes Jacob Pieter, with J.P. Morgan Securities LLC acting as the broker on Nasdaq within the next 90 days.

Who is selling NewAmsterdam Pharma (NAMS) shares and under what capacity?

The shares are expected to be sold in the next 90 days by Futurum B.V., with John Kastelein as director. The notice identifies Kastelein Johannes Jacob Pieter as the person for whose account the securities are to be sold and classifies him as an affiliate.

How were the NewAmsterdam Pharma (NAMS) shares to be sold acquired?

The 250,000 ordinary shares covered by the notice are tied to an option exercise from the issuer, dated 08/24/2026. The consideration for the option exercise is described as cash from the issuer to the selling party.

What is the reported market value and outstanding share count for NAMS in this notice?

The notice lists an aggregate market value of 6,967,500 for the 250,000 ordinary shares covered, and reports 119,537,169 ordinary shares outstanding for NewAmsterdam Pharma Co N.V., providing context for the relative size of the proposed sale.

On which market are the NewAmsterdam Pharma (NAMS) shares to be sold?

The ordinary shares covered by the notice are stated to be sold on Nasdaq, with J.P. Morgan Securities LLC identified as the broker handling the transaction from its New York office.

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

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Available on EDGAR 08/25/2026 - 04:47 PM EDT Accepted by SEC EDGAR 08/25/2026 - 04:47 PM EDT Learn about SEC filing dates

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144/A

144/A: Filer Information

Filer CIK	0002000389
Filer CCC	XXXXXXXX
Previous Accession Number Of The Filing	0001968582-26-000868
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144/A: Issuer Information

Name of Issuer	NewAmsterdam Pharma Company N.V.
SEC File Number	001-41562
Address of Issuer	Gooimeer 2-35 DC Naarden NETHERLANDS 1411
Phone	31-0-35-206-2971
Name of Person for Whose Account the Securities are To Be Sold	Kastelein Johannes Jacob Pieter
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Affiliate

144/A: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Ordinary Shares	J.P. Morgan Securities LLC 270 Park Avenue - 10th Floor New York NY 10017	250000	6967500	119537169	08/25/2026	Nasdaq

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144/A: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Ordinary Shares	08/24/2026	Option Exercise	Issuer			250000	08/24/2026	Cash

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144/A: Securities Sold During The Past 3 Months

Nothing to Report

144/A: Remarks and Signature

Remarks	The shares represented on this filing are for shares expected to be sold in the next 90 days by Futurum B.V., John Kastelein as Director
Date of Notice	08/24/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	03/31/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/ J.P. Morgan Securities LLC as agent and attorney-in-fact for Kastelein Johannes Jacob Pieter
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)