Johannes Jacob Pieter Kastelein is CSO at NewAmsterdam Pharma Co N.V. (NAMS). They have made 5 open-market trades across 1 company since 2024, most recently 2026-09-30.
CIK 0002000389
Unrated. We grade insiders only on stock they chose to buy on the open market. Grants, option exercises and vesting say nothing about timing, so they don't count — which is why someone can file often and still have no grade. It isn't a bad sign: unrated buys beat every graded tier below A.
0 open-market purchases, against 5 sales. Too few scored purchases to measure a record yet.
| Ticker | Shares | Value |
|---|---|---|
| NAMS | 69,302 | $1.4M |
Shares reported on the most recent Form 4, priced at the 2026-10-02 close.
Counted per filing, not per execution lot — a purchase filled in several tranches is one decision.
| Ticker | Type | Traded | Filed | Price | Value | 7d Stock | 30d Stock | 90d Stock |
|---|---|---|---|---|---|---|---|---|
| NAMS | SELL · 10b5-1 | 2026-09-30 | 2026-10-02 | $25.03 | $1.3M | -13.0% | -14.8% | — |
| NAMS | SELL · 10b5-1 | 2026-08-24 | 2026-08-25 | $26.91 | $3.4M | -6.5% | -16.2% | — |
| NAMS | SELL | 2026-03-05 | 2026-03-09 | $30.30 | $9.1M | -1.1% | +10.4% | +0.5% |
| NAMS | SELL | 2026-02-20 | 2026-02-24 | $35.31 | $1.6M | -17.4% | -13.5% | +0.1% |
| NAMS | SELL | 2026-01-05 | 2026-01-07 | $33.25 | $200K | -10.5% | -5.2% | -6.3% |
| NAMS | SELL | 2025-08-21 | 2025-08-25 | $24.86 | $3.7M | +9.8% | +8.9% | +59.9% |
| NAMS | SELL | 2024-03-26 | 2024-03-27 | $21.50 | $4.1M | -15.5% | -1.9% | -12.3% |
Grouped by shared companies and similar filing behaviour. This is a similarity measure, not a ranking or a performance signal.