Kastelein Johannes Jacob Pieter Insider Trading Activity
Kastelein Johannes Jacob Pieter has been net-selling over the last 12 months with 0 purchases and 9 sales across 1 company.
NAMS is the most-traded position with 9 trades. The largest single transaction was a sale of NAMS for $3.2M on Mar 5, 2026.
Performance Scorecard
Forward stock performance after each transaction by Kastelein Johannes Jacob Pieter. Buy returns measure price movement after open-market purchases; sell-avoided measures the loss avoided after open-market sales. Success rate counts trades where the insider's direction was right.
| PERIOD | AVG BUY RETURN | AVG SELL AVOIDED | SUCCESS RATE | TRADES |
|---|---|---|---|---|
| 30 days | — | -3.6% | 33% | 9 |
| 90 days | — | -19.6% | 0% | 9 |
| 120 days | — | -17.1% | 33% | 9 |
Performance based on stock price movement after each transaction date. Past results do not predict future returns. Not financial advice.
Price & Trades
Pro: Trade MarkersNAMS · NewAmsterdam Pharma Co N.V.
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| DATE | TICKER | TYPE | SHARES | PRICE | VALUE | Δ OWNED | ROLE | FILING |
|---|---|---|---|---|---|---|---|---|
Mar 9, 2026 | NAMS | Sell | 101,409 | $30.29 | $3.1M | −59.4% | Chief Scientific Officer | |
Mar 6, 2026 | NAMS | Sell | 94,124 | $30.32 | $2.9M | −57.6% | Chief Scientific Officer | |
Mar 5, 2026 | NAMS | Sell | 104,467 | $30.30 | $3.2M | −60.1% | Chief Scientific Officer | |
Feb 20, 2026 | NAMS | Sell | 30,789 | $35.46 | $1.1M | −36.5% | Chief Scientific Officer | |
Feb 20, 2026 | NAMS | Sell | 14,692 | $35.00 | $514K | −14.8% | Chief Scientific Officer | |
Jan 5, 2026 | NAMS | Sell | 6,000 | $33.25 | $200K | −7.5% | Chief Scientific Officer | |
Aug 22, 2025 | NAMS | Sell | 42,342 | $25.08 | $1.1M | −35.5% | Chief Scientific Officer | |
Aug 22, 2025 | NAMS | Sell | 7,658 | $25.49 | $195K | −10.0% | Chief Scientific Officer | |
Aug 21, 2025 | NAMS | Sell | 50,000 | $24.29 | $1.2M | −29.5% | Chief Scientific Officer |
Top Companies Traded
| TICKER | COMPANY | TRADES | TOTAL VOLUME |
|---|---|---|---|
| NAMS | NewAmsterdam Pharma Co N.V. | 9 | $13.4M |
Other insiders at NewAmsterdam Pharma Co N.V.
6 other tracked filers at NAMS.