ACM Research (ACMR) director sells 5K shares after option exercise

Rhea-AI Filing Summary

ACM Research director Charles C. Pappis reported a stock option exercise and related share sale. On March 5, 2026, he exercised a previously issued option for 5,000 shares of Class A Common Stock, receiving the shares at an exercise price of $29.1800 per share.

That same day, he sold 5,000 shares of Class A Common Stock in an open-market transaction at $50.0900 per share, leaving him with 0 shares directly owned after the transactions. The sale was carried out under a pre-established Rule 10b5-1 trading plan adopted on November 20, 2025, and the option was fully vested and exercisable.

Insider Trade Summary

Net Seller: 5,000 shares ($250,450)

Net Sell 3 txns

Insider Pappis Charles C

Role Director

Sold 5,000 shs ($250K)

Type	Security	Shares	Price	Value
Exercise	Stock Option	5,000	$0.00	--
Exercise	Class A Common Stock	5,000	$29.18	$146K
Sale	Class A Common Stock	5,000	$50.09	$250K

Holdings After Transaction: Stock Option — 5,000 shares (Direct); Class A Common Stock — 5,000 shares (Direct)

Footnotes (1)

1. On March 5, 2026, the reporting person exercised a previously issued stock option to purchase 5,000 shares of Class A Common Stock of the Issuer. The sale reported on this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on November 20, 2025. The option is fully vested and exercisable.

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Form 4 Insider Transactions: What Each Field Means →

SEC Form 4

FORM 4

UNITED 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^*

Pappis Charles C

(Last) (First) (Middle)

C/O ACM RESEARCH, INC.

42307 OSGOOD ROAD, SUITE I

(Street)

FREMONT CA 94539

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
ACM Research, Inc. [ ACMR ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
03/05/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

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)
			Code	V	Amount	(A) or (D)	Price
Class A Common Stock	03/05/2026		M(1)		5,000	A	$29.18	5,000	D
Class A Common Stock	03/05/2026		S(2)		5,000	D	$50.09	0	D

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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Option	$29.18	03/05/2026		M(1)			5,000	(3)	03/14/2035	Class A Common Stock	5,000	$0	5,000	D

Explanation of Responses:

1. On March 5, 2026, the reporting person exercised a previously issued stock option to purchase 5,000 shares of Class A Common Stock of the Issuer.

2. The sale reported on this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on November 20, 2025.

3. The option is fully vested and exercisable.

	/s/ Mark McKechnie, Attorney-in-Fact for Charles Pappis	03/09/2026
	** Signature of Reporting Person	Date
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.

FAQ

What insider transactions did ACMR director Charles C. Pappis report?

Director Charles C. Pappis exercised options for 5,000 shares and sold 5,000 ACMR Class A Common shares. The option exercise price was $29.1800 per share, and the subsequent open-market sale price was $50.0900 per share on March 5, 2026.

How many ACMR shares did Charles C. Pappis sell and at what price?

Charles C. Pappis sold 5,000 ACMR Class A Common shares at $50.0900 per share. The transaction was an open-market sale executed on March 5, 2026, following an option exercise that delivered the same number of shares earlier that day.

Were the ACMR insider transactions by Charles C. Pappis under a 10b5-1 plan?

Yes, the sale of 5,000 ACMR shares by Charles C. Pappis was made under a Rule 10b5-1 trading plan. The plan was adopted on November 20, 2025, providing a pre-arranged framework for selling shares automatically on specified terms.

What stock options did ACMR director Charles C. Pappis exercise?

Charles C. Pappis exercised a fully vested, exercisable stock option to purchase 5,000 shares of ACMR Class A Common Stock. The exercise occurred on March 5, 2026, at an option exercise price of $29.1800 per share, immediately preceding the related share sale.

How many ACMR shares did Charles C. Pappis own after these transactions?

After exercising options and then selling the resulting shares, Charles C. Pappis reported owning 0 ACMR Class A Common shares directly. The Form 4 shows 5,000 shares sold at $50.0900 per share, matching the 5,000 shares acquired through the option exercise.