Question 1

What stocks has Dun Haiping been buying?

Accepted Answer

InsiderAct tracks all open-market stock purchases disclosed by Dun Haiping 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 Dun Haiping's recent Form 4 filings?

Accepted Answer

All Form 4 filings by Dun Haiping 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.


2026-05-21	2026-05-19	ACMR Acm Research, Inc.	Director	Exercise Conversion	5,000	$5.60	$28,000
2026-05-21	2026-05-19	ACMR Acm Research, Inc.	Director	Sale	1,858	$67.54	$125,489
2026-05-21	2026-05-19	ACMR Acm Research, Inc.	Director	Sale	1,333	$63.84	$85,099
2026-05-21	2026-05-19	ACMR Acm Research, Inc.	Director	Sale	1,309	$67.21	$87,978
2026-05-21	2026-05-19	ACMR Acm Research, Inc.	Director	Sale	500	$65.09	$32,545
2026-05-21	2026-05-19	ACMR Acm Research, Inc.	Director	Exercise Conversion	5,000	$5.60	$28,000
2026-03-11	2026-03-09	ACMR Acm Research, Inc.	Director	Exercise Conversion	5,000	$0.00	$0
2026-03-11	2026-03-09	ACMR Acm Research, Inc.	Director	Sale	4,100	$43.37	$177,817
2026-03-11	2026-03-09	ACMR Acm Research, Inc.	Director	Sale	900	$43.94	$39,546
2026-03-11	2026-03-09	ACMR Acm Research, Inc.	Director	Exercise Conversion	5,000	$5.60	$28,000

Dun Haiping

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