Johannes Jacob Pieter Kastelein
CIK: 0002000389
Transaction Breakdown
High conviction signal
Position reduction
Derivative conversions
Compensation grants
Gifts, tax withholding, conversions, dispositions to the issuer and other codes
Companies & Roles (1)
NewAmsterdam Pharma Co N.V.
Discretionary Trading P&L
Holdings
Transaction History (22 total)
- Sep 30, 2026NAMS
NewAmsterdam Pharma Co N.V.
Exercise(M)Indirect50.2K shares- - Sep 30, 2026NAMS
NewAmsterdam Pharma Co N.V.
Sale(S)Indirect50.2K shares at avg. $25.03$1.3M - Aug 24, 2026NAMS
NewAmsterdam Pharma Co N.V.
Sale(S)Indirect125K shares at avg. $26.91$3.4M - Aug 24, 2026NAMS
NewAmsterdam Pharma Co N.V.
Exercise(M)Indirect125K shares- - Mar 9, 2026NAMS
NewAmsterdam Pharma Co N.V.
Sale(S)Indirect101.4K shares at avg. $30.29$3.1M - Mar 9, 2026NAMS
NewAmsterdam Pharma Co N.V.
Exercise(M)Indirect101.4K shares- - Mar 6, 2026NAMS
NewAmsterdam Pharma Co N.V.
Exercise(M)Indirect94.1K shares- - Mar 6, 2026NAMS
NewAmsterdam Pharma Co N.V.
Sale(S)Indirect94.1K shares at avg. $30.32$2.9M - Mar 5, 2026NAMS
NewAmsterdam Pharma Co N.V.
Exercise(M)Indirect104.5K shares- - Mar 5, 2026NAMS
NewAmsterdam Pharma Co N.V.
Sale(S)Indirect104.5K shares at avg. $30.30$3.2M - Feb 20, 2026NAMS
NewAmsterdam Pharma Co N.V.
Sale(S)Direct30.8K shares at avg. $35.46$1.1M - Feb 20, 2026NAMS
NewAmsterdam Pharma Co N.V.
Sale(S)Direct14.7K shares at avg. $35.00$514K - Jan 7, 2026NAMS
NewAmsterdam Pharma Co N.V.
Award(A)Direct25.5K shares- - Jan 5, 2026NAMS
NewAmsterdam Pharma Co N.V.
Sale(S)Direct6K shares at avg. $33.25$200K - Aug 22, 2025NAMS
NewAmsterdam Pharma Co N.V.
Sale(S)Indirect42.3K shares at avg. $25.08$1.1M - Aug 22, 2025NAMS
NewAmsterdam Pharma Co N.V.
Sale(S)Indirect7.7K shares at avg. $25.49$195K - Aug 21, 2025NAMS
NewAmsterdam Pharma Co N.V.
Sale(S)Indirect50K shares at avg. $24.29$1.2M - Mar 26, 2025NAMS
NewAmsterdam Pharma Co N.V.
Exercise(M)Direct45.5K shares- - Mar 26, 2025NAMS
NewAmsterdam Pharma Co N.V.
Award(A)Indirect19.3K shares- - Mar 24, 2025NAMS
NewAmsterdam Pharma Co N.V.
Exercise(M)Indirect150K shares- - Jan 7, 2025NAMS
NewAmsterdam Pharma Co N.V.
Award(A)Direct34K shares- - Jan 2, 2025NAMS
NewAmsterdam Pharma Co N.V.
Award(A)DirectOption (right to buy)
200K shares-
| Type | Shares | Price | Ownership | |||
|---|---|---|---|---|---|---|
| Sep 30, 2026 | NAMS NewAmsterdam Pharma Co N.V. | Exercise(M) | 50,246 | - | $0 | Indirect |
| Sep 30, 2026 | NAMS NewAmsterdam Pharma Co N.V. | Sale(S) | 50,246 | $25.03 | $1,257,657 | Indirect |
| Aug 24, 2026 | NAMS NewAmsterdam Pharma Co N.V. | Sale(S) | 125,000 | $26.91 | $3,363,750 | Indirect |
| Aug 24, 2026 | NAMS NewAmsterdam Pharma Co N.V. | Exercise(M) | 125,000 | - | $0 | Indirect |
| Mar 9, 2026 | NAMS NewAmsterdam Pharma Co N.V. | Sale(S) | 101,409 | $30.29 | $3,071,679 | Indirect |
| Mar 9, 2026 | NAMS NewAmsterdam Pharma Co N.V. | Exercise(M) | 101,409 | - | $0 | Indirect |
| Mar 6, 2026 | NAMS NewAmsterdam Pharma Co N.V. | Exercise(M) | 94,124 | - | $0 | Indirect |
| Mar 6, 2026 | NAMS NewAmsterdam Pharma Co N.V. | Sale(S) | 94,124 | $30.32 | $2,853,840 | Indirect |
| Mar 5, 2026 | NAMS NewAmsterdam Pharma Co N.V. | Exercise(M) | 104,467 | - | $0 | Indirect |
| Mar 5, 2026 | NAMS NewAmsterdam Pharma Co N.V. | Sale(S) | 104,467 | $30.30 | $3,165,350 | Indirect |
| Feb 20, 2026 | NAMS NewAmsterdam Pharma Co N.V. | Sale(S) | 30,789 | $35.46 | $1,091,778 | Direct |
| Feb 20, 2026 | NAMS NewAmsterdam Pharma Co N.V. | Sale(S) | 14,692 | $35.00 | $514,220 | Direct |
| Jan 7, 2026 | NAMS NewAmsterdam Pharma Co N.V. | Award(A) | 25,500 | - | $0 | Direct |
| Jan 5, 2026 | NAMS NewAmsterdam Pharma Co N.V. | Sale(S) | 6,000 | $33.25 | $199,500 | Direct |
| Aug 22, 2025 | NAMS NewAmsterdam Pharma Co N.V. | Sale(S) | 42,342 | $25.08 | $1,061,937 | Indirect |
| Aug 22, 2025 | NAMS NewAmsterdam Pharma Co N.V. | Sale(S) | 7,658 | $25.49 | $195,202 | Indirect |
| Aug 21, 2025 | NAMS NewAmsterdam Pharma Co N.V. | Sale(S) | 50,000 | $24.29 | $1,214,500 | Indirect |
| Mar 26, 2025 | NAMS NewAmsterdam Pharma Co N.V. | Exercise(M) | 45,481 | - | - | Direct |
| Mar 26, 2025 | NAMS NewAmsterdam Pharma Co N.V. | Award(A) | 19,302 | - | - | Indirect |
| Mar 24, 2025 | NAMS NewAmsterdam Pharma Co N.V. | Exercise(M) | 150,000 | - | - | Indirect |
| Jan 7, 2025 | NAMS NewAmsterdam Pharma Co N.V. | Award(A) | 34,000 | - | $0 | Direct |
| Jan 2, 2025 | NAMS NewAmsterdam Pharma Co N.V. | Award(A) Option (right to buy) | 200,000 | - | - | Direct |
1-22 of 22 transactions
About Kastelein Johannes Jacob Pieter
Kastelein Johannes Jacob Pieter (SEC CIK 0002000389) files insider reports with the SEC as Chief Scientific Officer of NewAmsterdam Pharma Co N.V. (NAMS).
Signal8 holds 10 ownership filings by Kastelein Johannes Jacob Pieter, all Form 4s, filed between Jan 6, 2025 and Oct 2, 2026. Those filings report 22 transactions, from Jan 2, 2025 to Sep 30, 2026. Signal8's Form 4 history starts in Sep 2024.
The business address on Kastelein Johannes Jacob Pieter's filings is in NAARDEN.
Recent filings by Kastelein Johannes Jacob Pieter
- Sep 30, 2026: Option exercise of NAMS shares (Form 4, code M).
- Sep 30, 2026: Open-market sale of NAMS shares (Form 4, code S).
- Aug 24, 2026: Open-market sale of NAMS shares (Form 4, code S).
- Aug 24, 2026: Option exercise of NAMS shares (Form 4, code M).
- Mar 9, 2026: Open-market sale of NAMS shares (Form 4, code S).
Other insiders filing for NewAmsterdam Pharma Co N.V. (NAMS)
- Davidson Michael H., Chief Executive Officer
- Smither John W, Director
- Gunning Robert William, Vice President, Controller
- Kooij Louise Frederika, Chief Accounting Officer
- LANGE LOUIS G, Director
- Somaiya Mayur Ian, Chief Financial Officer