STOCK TITAN

ACM Research (ACMR) director exercises options, sells shares under plan

(Neutral)
(Neutral)
Form Type
4

Rhea-AI Filing Summary

ACM Research, Inc. (ACMR) director Haiping Dun exercised stock options for 5,000 shares of Class A Common Stock at an exercise price of $5.60 per share, from a fully vested option, and on the same date sold 5,000 shares in multiple open-market transactions at weighted average prices between $79.89 and $82.33 pursuant to a Rule 10b5-1 trading plan adopted on August 13, 2025. Following the option exercise, Dun held 45,000 stock options directly and reported indirect holdings of 100,000 shares in the Dun Family GST Trust and 755,090 shares in the Haiping Dun & Chi-Pin H Dun Revocable Trust.

Positive

  • None.

Negative

  • None.
Insider Dun Haiping
Role Director
Sold 5,000 shs ($406K)
Approx. gross sale proceeds $406K
Approx. exercise cost $28K
Approx. pre-tax spread $378K
Type Security Shares Price Value
Exercise Stock Option F5 5,000 $0.00 $0.00
Exercise Class A Common Stock 5,000 $5.60 $28K
Sale Class A Common Stock F1, F2 1,200 $80.29 $96K
Sale Class A Common Stock F1, F3 3,400 $81.31 $276K
Sale Class A Common Stock F1, F4 400 $82.17 $33K
holding Class A Common Stock -- -- --
holding Class A Common Stock -- -- --
Holdings After Transaction: Stock Option — 45,000 shares (Direct); Class A Common Stock — 0 shares (Direct); Class A Common Stock — 100,000 shares (Indirect, Dun Family GST Trust); Class A Common Stock — 755,090 shares (Indirect, Haiping Dun & Chi-Pin H Dun Revocable Trust)
Footnotes (5)
  1. F1. The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 13, 2025.
  2. F2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $79.89 to $80.77, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (2), (3), and (4) to this Form 4.
  3. F3. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $80.95 to $81.91, inclusive.
  4. F4. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $81.97 to $82.33, inclusive.
  5. F5. The option is fully vested and exercisable.
Options exercised 5,000 shares Stock option exercise into Class A Common Stock on 2026-08-18
Option exercise price $5.60 per share Exercise price of stock option expiring 2029-04-22
Shares sold at $80.29 1,200 shares at $80.29 per share Weighted average price, trades ranged from $79.89 to $80.77
Shares sold at $81.31 3,400 shares at $81.31 per share Weighted average price, trades ranged from $80.95 to $81.91
Shares sold at $82.17 400 shares at $82.17 per share Weighted average price, trades ranged from $81.97 to $82.33
Options held after transaction 45,000 options Total stock options following the reported exercise
Indirect GST Trust holdings 100,000 shares Class A Common Stock held via Dun Family GST Trust
Indirect Revocable Trust holdings 755,090 shares Class A Common Stock held via Haiping Dun & Chi-Pin H Dun Revocable Trust
Rule 10b5-1 trading plan regulatory
"The sales reported ... were effected pursuant to a Rule 10b5-1 trading plan"
A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.
weighted average price financial
"The price reported in Column 4 is a weighted average price."
Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.
Class A Common Stock financial
"underlying_security_title: "Class A Common Stock""
Class A common stock is a category of a company’s shares that carries a specific set of ownership rights—most commonly defined voting power and claims on dividends—set out in the company’s charter. For investors it matters because the class determines how much influence you have over corporate decisions, the share’s likely dividend and trading behavior, and how it compares in value to other share classes, like choosing a particular seat with different privileges at the company’s decision-making table.
stock option financial
"security_title: "Stock Option" with an exercise price of $5.6000"
A stock option is a contract that gives you the right to buy or sell a company's stock at a specific price within a certain time frame. People use them to potentially make money if the stock's price moves favorably or to protect against losses. It's like holding a coupon that can be used to buy or sell stock at a set price later on.
indirect ownership financial
"ownership_type: "indirect" through named trusts"

FAQ

What insider transactions did ACMR director Haiping Dun report on this Form 4?

Haiping Dun reported exercising 5,000 stock options at $5.60 per share and selling a total of 5,000 Class A Common shares in multiple open-market transactions at weighted average prices between $79.89 and $82.33 on August 18, 2026.

At what prices did Haiping Dun sell ACMR shares?

Dun sold ACMR Class A Common Stock in three groups: 1,200 shares at a weighted average of $80.29, 3,400 shares at $81.31, and 400 shares at $82.17, with actual trade prices ranging from $79.89 to $82.33.

Were Haiping Dun’s ACMR stock sales under a Rule 10b5-1 trading plan?

Yes. The filing states the sales were effected pursuant to a Rule 10b5-1 trading plan adopted by Haiping Dun on August 13, 2025, indicating the trades followed a pre-arranged plan rather than ad hoc timing decisions.

How many stock options does Haiping Dun hold after these ACMR transactions?

After exercising 5,000 options, Dun held 45,000 stock options on ACM Research, Inc. common stock, with the reported option having an exercise price of $5.60 per share and an expiration date of April 22, 2029.

What indirect ACMR share holdings did Haiping Dun report?

Dun reported indirect ownership of 100,000 shares of Class A Common Stock through the Dun Family GST Trust and 755,090 shares through the Haiping Dun & Chi-Pin H Dun Revocable Trust, in addition to his direct positions.

What is the net share impact of Haiping Dun’s reported ACMR trades?

The transactions show a net disposition of 5,000 shares of Class A Common Stock, based on 5,000 shares acquired via option exercise and 5,000 shares sold in open-market transactions, resulting in a net-sell position for the reported date.

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Learn about SEC filing dates
SEC Form 4
FORM 4UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940
OMB APPROVAL
OMB Number:3235-0287
Estimated average burden
hours per response:0.5
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
X
Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.
1. Name and Address of Reporting Person*
Dun Haiping

(Last)(First)(Middle)
C/O ACM RESEARCH, INC.
42307 OSGOOD ROAD, SUITE I

(Street)
FREMONT CALIFORNIA 94539

(City)(State)(Zip)

UNITED STATES

(Country)
2. Issuer Name and Ticker or Trading Symbol
ACM Research, Inc. [ ACMR ]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
XDirector10% Owner
Officer (give title below)Other (specify below)
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
08/18/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm filed by One Reporting Person
Form filed by More than One Reporting Person
4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year)2A. Deemed Execution Date, if any (Month/Day/Year)3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4)
CodeVAmount(A) or (D)Price
Class A Common Stock08/18/2026M5,000A$5.65,000D
Class A Common Stock08/18/2026S(1)1,200D$80.29(2)3,800D
Class A Common Stock08/18/2026S(1)3,400D$81.31(3)400D
Class A Common Stock08/18/2026S(1)400D$82.17(4)0D
Class A Common Stock100,000IDun Family GST Trust
Class A Common Stock755,090IHaiping Dun & Chi-Pin H Dun Revocable Trust
Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year)3A. Deemed Execution Date, if any (Month/Day/Year)4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 6. Date Exercisable and Expiration Date (Month/Day/Year)7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Stock Option$5.608/18/2026M5,000 (5)04/22/2029Class A Common Stock5,000$045,000D
Explanation of Responses:
1. The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 13, 2025.
2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $79.89 to $80.77, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (2), (3), and (4) to this Form 4.
3. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $80.95 to $81.91, inclusive.
4. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $81.97 to $82.33, inclusive.
5. The option is fully vested and exercisable.
/s/ Mark McKechnie, Attorney-in-Fact for Haiping Dun08/20/2026
** Signature of Reporting PersonDate
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)