Question 1

What stocks has Kastelein Johannes Jacob Pieter been buying?

Accepted Answer

InsiderAct tracks all open-market stock purchases disclosed by Kastelein Johannes Jacob Pieter via SEC Form 4 filings. These are publicly disclosed transactions that corporate insiders must file with the SEC within 2 business days of any stock transaction.

Question 2

How do I interpret an insider's transaction history?

Accepted Answer

Focus on open-market purchases (Form 4 code "P"), which represent voluntary personal capital commitments. Large purchases ($100,000+), repeated buying over time, and purchases during price declines are the most meaningful signals. Option exercises, stock awards, and automatic plan transactions are less informative.

Question 3

Are insider transactions reliable investment signals?

Accepted Answer

Insider buying is generally a more reliable signal than selling. Insiders buy for one primary reason — they believe the stock will rise. The strongest buying signals involve large dollar amounts, purchases during price declines, and cluster buying where multiple insiders buy simultaneously.

Question 4

Where can I see all of Kastelein Johannes Jacob Pieter's recent Form 4 filings?

Accepted Answer

All Form 4 filings by Kastelein Johannes Jacob Pieter are available on this InsiderAct profile page, sourced directly from SEC EDGAR. Each transaction shows the date, shares bought or sold, price per share, transaction code, and resulting ownership position. You can also view the original filing on SEC EDGAR for the complete disclosure.

Question 5

What is the difference between an officer and a director insider purchase?

Accepted Answer

Officer purchases (CEOs, CFOs, COOs) are generally considered stronger signals than director purchases because officers have deeper day-to-day visibility into company operations and financials. A director may be buying for governance or relationship reasons. Both are meaningful, but C-suite officer buying carries more informational weight — especially for large, discretionary purchases.


2026-03-10	2026-03-09	NAMS Newamsterdam Pharma Co N.V.	CSO	Sale	101,409	$30.29	$3,071,679
2026-03-10	2026-03-09	NAMS Newamsterdam Pharma Co N.V.	CSO	Exercise Conversion	101,409	$0.00	$0
2026-03-10	2026-03-09	NAMS Newamsterdam Pharma Co N.V.	CSO	Exercise Conversion	101,409	$0.00	$0
2026-03-10	2026-03-06	NAMS Newamsterdam Pharma Co N.V.	CSO	Exercise Conversion	94,124	$0.00	$0
2026-03-10	2026-03-06	NAMS Newamsterdam Pharma Co N.V.	CSO	Exercise Conversion	94,124	$0.00	$0
2026-03-10	2026-03-06	NAMS Newamsterdam Pharma Co N.V.	CSO	Sale	94,124	$30.32	$2,853,840
2026-03-10	2026-03-05	NAMS Newamsterdam Pharma Co N.V.	CSO	Exercise Conversion	104,467	$0.00	$0
2026-03-10	2026-03-05	NAMS Newamsterdam Pharma Co N.V.	CSO	Sale	104,467	$30.30	$3,165,350
2026-03-10	2026-03-05	NAMS Newamsterdam Pharma Co N.V.	CSO	Exercise Conversion	104,467	$0.00	$0
2026-02-24	2026-02-20	NAMS Newamsterdam Pharma Co N.V.	CSO	Sale	30,789	$35.46	$1,091,778

Kastelein Johannes Jacob Pieter

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