Johannes Jacob Pieter Kastelein sold $9.1M of NAMS
Chief Scientific Officer at NewAmsterdam Pharma Co N.V.. 300,000 shares at an average of $30.30, traded Mar 5, 2026, filed Mar 9, 2026.
Score components
- +15RoleOfficer
- +25Trade size$9.1M at market
- +20Share of holdings soldSold 100% of holdings
- +15Cluster3 insiders selling within 14 days
- -15Exercise and sellShares came from an option exercise in the same filing
- -2010b5-1 planPre-scheduled under a 10b5-1 plan
What happened after comparable sells
Same side and tier, against the S&P 500, at 1, 3 and 6 months. Shown to Pro users; the whole table is on the backtest page.
This signal so far: 1m +10.5%, 3m +0.6%, 6m -17.5%.
Price around the trade, and since
From a quarter before the trade to today. The arrow is the trade, the circle the day the filing reached EDGAR, which is the first day anyone outside could act; the dotted line is the S&P 500 rebased to that day's close.
Daily candles, adjusted for splits and dividends. Green arrows are insider buys, red are sells, sized by value; the dashed line is the close on the filing day, the dotted line SPY rebased to it.Charts by TradingView Lightweight Charts™
Rows in this filing
Every transaction in Form 4 0001193125-26-099073, as filed. Open on EDGAR
| Date | Transaction | Shares | Price | Value | Holdings after | Filed |
|---|---|---|---|---|---|---|
| Mar 5, 2026 | MOption exercise Ordinary Sharesindirect: See footnote10b5-1 | +104,467 | - | - | 173,769 | Mar 9, 2026 |
| Mar 5, 2026 | SOpen-market sale Ordinary Sharesindirect: See footnote10b5-1 | -104,467 | $30.30 | $3.2M | 69,302 | Mar 9, 2026 |
| Mar 6, 2026 | MOption exercise Ordinary Sharesindirect: See footnote10b5-1 | +94,124 | - | - | 163,426 | Mar 9, 2026 |
| Mar 6, 2026 | SOpen-market sale Ordinary Sharesindirect: See footnote10b5-1 | -94,124 | $30.32 | $2.9M | 69,302 | Mar 9, 2026 |
| Mar 9, 2026 | MOption exercise Ordinary Sharesindirect: See footnote10b5-1 | +101,409 | - | - | 170,711 | Mar 9, 2026 |
| Mar 9, 2026 | SOpen-market sale Ordinary Sharesindirect: See footnote10b5-1 | -101,409 | $30.29 | $3.1M | 69,302 | Mar 9, 2026 |
| Mar 5, 2026 | MOption exercise Option (right to buy)derivativeindirect: See footnote10b5-1 | -104,467 | $0.00 | $0 | 715,762 | Mar 9, 2026 |
| Mar 6, 2026 | MOption exercise Option (right to buy)derivativeindirect: See footnote10b5-1 | -94,124 | $0.00 | $0 | 621,638 | Mar 9, 2026 |
| Mar 9, 2026 | MOption exercise Option (right to buy)derivativeindirect: See footnote10b5-1 | -101,409 | $0.00 | $0 | 520,229 | Mar 9, 2026 |
Related signals
Other insiders at NewAmsterdam Pharma Co N.V. and this insider’s other filings.
| Score | Company | Insider | Value | Holdings | Filed |
|---|---|---|---|---|---|
| 15Weak | NewAmsterdam Pharma Co N.V. | Johannes Jacob Pieter Kastelein Chief Scientific Officer | $1.3M 50,246 shares | -42% | |
| 38Weak | NAMSbuy NewAmsterdam Pharma Co N.V. | Michael H. Davidson Chief Executive Officer | $227k 10,000 shares | +1% | |
| 34Weak | NewAmsterdam Pharma Co N.V. | John W Smither director | $41k 1,600 shares | -15% | |
| 33Weak | NewAmsterdam Pharma Co N.V. | Johannes Jacob Pieter Kastelein Chief Scientific Officer | $3.4M 125,000 shares | -64% | |
| 25Weak | NewAmsterdam Pharma Co N.V. | Louise Frederika Kooij Chief Accounting Officer | $3.2M 105,000 shares | -81% | |
| 25Weak | NewAmsterdam Pharma Co N.V. | Louise Frederika Kooij Chief Accounting Officer | $1.2M 40,000 shares | -62% | |
| 25Weak | NewAmsterdam Pharma Co N.V. | Louise Frederika Kooij Chief Accounting Officer | $2.3M 65,000 shares | -73% | |
| 75Notable | NewAmsterdam Pharma Co N.V. | Louis G Lange director | $1.4M 44,619 shares | -81% | |
| 73Notable | NewAmsterdam Pharma Co N.V. | Louis G Lange director | $829k 28,186 shares | -100% | |
| 70Notable | NewAmsterdam Pharma Co N.V. | Michael H. Davidson Chief Executive Officer | $15M 443,707 shares | -72% |
Not investment advice. Scores and forward returns are decision support built from public SEC filings and past prices; they describe what happened after comparable filings, not what will happen after this one. Do your own research and size your risk.