InsiderTrades

Kastelein Johannes Jacob Pieter

SEC CIK 2000389 · EDGAR

Buying vs selling by month open-market trades, last 31 months, NAMS
BoughtSold

Companies

TickerCompanyTitleHoldingBoughtSoldTradesFirstLast
NAMSNewAmsterdam Pharma Co N.V.CSO, Dir 194.3K — $20.83M 152024-03-262026-08-24

Most active insiders at NAMS, 12 months

#InsiderTitleBoughtSold
1 Davidson Michael H.CEO, Dir $226.5K$25.33M
2 Kooij Louise FrederikaCAO —$16.75M
3 Kastelein Johannes Jacob PieterCSO, Dir —$14.26M
4 Somaiya Mayur IanCFO —$3.43M
5 LANGE LOUIS GDir —$2.19M
6 Smither John WDir —$40.5K
7 Gunning Robert WilliamVP, Ctrl ——
8 van der Kamp Hilde JohannaDir ——
9 McKenna Mark C.Dir ——
10 Gulfo Adele M.Dir ——

Transactions 15

Type
Reset
X Filed Traded Ticker Company Insider Title Type Price Qty Owned ΔOwn Value
DTI 2026-08-25 16:30 2026-08-24 NAMS NewAmsterdam Pharma Co N.V. Kastelein Johannes Jacob Pieter CSO, Dir M - OptEx — +125.0K 194.3K +180% —
DTI 2026-08-25 16:30 2026-08-24 NAMS NewAmsterdam Pharma Co N.V. Kastelein Johannes Jacob Pieter CSO, Dir S - Sale+OE $26.91 -125.0K 69.3K -64% -$3.36M
DMTI 2026-03-09 2026-03-05+ NAMS NewAmsterdam Pharma Co N.V. Kastelein Johannes Jacob Pieter CSO, Dir M - OptEx — +300.0K 170.7K New —
DMTI 2026-03-09 2026-03-05+ NAMS NewAmsterdam Pharma Co N.V. Kastelein Johannes Jacob Pieter CSO, Dir S - Sale+OE $30.30 -300.0K 69.3K -81% -$9.09M
M 2026-02-24 2026-02-20 NAMS NewAmsterdam Pharma Co N.V. Kastelein Johannes Jacob Pieter CSO, Dir S - Sale $35.31 -45.5K 84.3K -35% -$1.61M
DT 2026-01-07 2026-01-05 NAMS NewAmsterdam Pharma Co N.V. Kastelein Johannes Jacob Pieter CSO, Dir S - Sale $33.25 -6,000 73.5K -8% -$199.5K
DT 2026-01-07 2026-01-07 NAMS NewAmsterdam Pharma Co N.V. Kastelein Johannes Jacob Pieter CSO, Dir A - Grant — +25.5K 99.0K +35% —
MI 2025-08-25 2025-08-21+ NAMS NewAmsterdam Pharma Co N.V. Kastelein Johannes Jacob Pieter CSO, Dir S - Sale $24.72 -100.0K 77.0K -57% -$2.47M
D 2025-03-28 2025-03-26 NAMS NewAmsterdam Pharma Co N.V. Kastelein Johannes Jacob Pieter CSO, Dir M - OptEx $0.00 +45.5K 79.5K +134% $0
DI 2025-03-28 2025-03-26 NAMS NewAmsterdam Pharma Co N.V. Kastelein Johannes Jacob Pieter CSO, Dir A - Grant $0.00 +19.3K 169.3K +13% $0
DI 2025-03-26 2025-03-24 NAMS NewAmsterdam Pharma Co N.V. Kastelein Johannes Jacob Pieter CSO, Dir M - OptEx — +150.0K 150.0K New —
2025-01-07 2025-01-07 NAMS NewAmsterdam Pharma Co N.V. Kastelein Johannes Jacob Pieter CSO, Dir A - Grant — +34.0K 34.0K New —
DI 2024-03-27 2024-03-26 NAMS NewAmsterdam Pharma Co N.V. Kastelein Johannes Jacob Pieter CSO, Dir S - Sale+OE $21.50 -190.5K 0 -100% -$4.10M
DI 2024-03-27 2024-03-26 NAMS NewAmsterdam Pharma Co N.V. Kastelein Johannes Jacob Pieter CSO, Dir F - Tax $22.72 -11.2K 190.5K -6% -$254.4K
DI 2024-03-27 2024-03-26 NAMS NewAmsterdam Pharma Co N.V. Kastelein Johannes Jacob Pieter CSO, Dir M - OptEx — +201.7K 201.7K New —

Purchase Sale Sale after option exercise All abbreviations