ACM Research (ACMR) director sells 5,000 shares after exercising options

Rhea-AI Filing Summary

ACM Research director Charles C. Pappis reported an option exercise paired with an open-market sale of shares. On April 17, 2026, he sold 5,000 shares of Class A Common Stock at $52.00 per share in an open-market transaction. That same day, he exercised a previously issued stock option covering 5,000 shares at an exercise price of $29.18 per share, and the option is now fully exercised. The sale was carried out under a pre-arranged Rule 10b5-1 trading plan adopted on November 20, 2025, indicating the timing of the transaction was planned in advance.

Insights

Equity compensation and insider-trading analyst

Pre-planned option exercise and matching share sale; limited signal.

Director Charles C. Pappis exercised a stock option for 5,000 ACM Research Class A shares at an exercise price of $29.18, then sold 5,000 shares at $52.00 in an open-market transaction. This is a classic option exercise-and-sell pattern.

The filing shows one derivative transaction and a net disposition of 5,000 shares, with no remaining options from this grant. A key detail is that the sale was executed under a Rule 10b5-1 trading plan adopted on November 20, 2025, suggesting the trade was pre-scheduled rather than based on short-term news.

Because the transaction is compensation-related and pre-planned, and the filing does not quantify the director’s broader holdings, it generally reads as routine personal liquidity rather than a strong directional signal about ACM Research’s outlook.

Insider Trade Summary 10b5-1

Net Seller: 5,000 shares ($260,000)

Net Sell 3 txns

Insider Pappis Charles C

Role null

Sold 5,000 shs ($260K)

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	$52.00	$260K

Holdings After Transaction: Stock Option — 0 shares (Direct, null); Class A Common Stock — 5,000 shares (Direct, null)

Footnotes (1)

1. On April 17, 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.

Key Figures

Shares sold: 5,000 shares Sale price: $52.00/share Options exercised: 5,000 options +3 more

6 metrics

Shares sold 5,000 shares Open-market sale of Class A Common Stock at $52.00 per share on April 17, 2026

Sale price $52.00/share Open-market disposition of 5,000 Class A shares

Options exercised 5,000 options Stock option for 5,000 Class A shares exercised on April 17, 2026

Exercise price $29.18/share Exercise price of the fully vested stock option converted into Class A shares

Net share change -5,000 shares Transaction summary shows net-sell direction of 5,000 shares for this filing

Derivative positions remaining 0 options Derivative summary shows no remaining options from the exercised grant

Key Terms

Rule 10b5-1 trading plan, stock option, Class A Common Stock, derivative security

4 terms

Rule 10b5-1 trading plan regulatory

"The sale reported on this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person"

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.

stock option financial

"the reporting person exercised a previously issued stock option to purchase 5,000 shares of Class A Common Stock"

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.

Class A Common Stock financial

"5,000 shares of Class A Common Stock of the Issuer"

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.

derivative security financial

"transaction_code_description: Exercise or conversion of derivative security"

A derivative security is a financial contract whose value comes from the price or performance of something else, such as a stock, bond, commodity, or market index. For investors it acts like an insurance policy or a wager: it can be used to protect against losses, lock in prices, or amplify gains and losses, so it can change a portfolio’s risk and potential return without owning the underlying asset directly.

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 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)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
04/17/2026

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

X	Form 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)
			Code	V	Amount	(A) or (D)	Price
Class A Common Stock	04/17/2026		M(1)		5,000	A	$29.18	5,000	D
Class A Common Stock	04/17/2026		S(2)		5,000	D	$52	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	04/17/2026		M(1)			5,000	(3)	03/14/2035	Class A Common Stock	5,000	$0	0	D

Explanation of Responses:

1. On April 17, 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	04/21/2026
	** 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.
* Form 4: SEC 1474 (03-26)

FAQ

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

Charles C. Pappis reported an open-market sale of 5,000 ACM Research Class A shares at $52.00 each. On the same day, he exercised a stock option for 5,000 shares at a $29.18 exercise price, turning option value into cash via the sale.

Was the ACMR insider sale by Charles C. Pappis part of a trading plan?

Yes. The sale was executed under a Rule 10b5-1 trading plan adopted on November 20, 2025. Such plans pre-schedule trades, reducing the likelihood that timing reflects non-public information or a sudden change in the insider’s view of the company.

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

He sold 5,000 shares of ACM Research Class A Common Stock at $52.00 per share. This was an open-market transaction reported on Form 4 and paired with an option exercise for the same number of underlying shares that day.

What stock option did Charles C. Pappis exercise in the ACMR Form 4?

He exercised a previously issued stock option covering 5,000 ACM Research Class A shares at a $29.18 exercise price. The option is described as fully vested and exercisable, and following this exercise, the related derivative position under that option grant is eliminated.

Does the ACMR Form 4 show remaining stock options for Charles C. Pappis?

The Form 4 indicates a derivative transaction for 5,000 stock options exercised into Class A shares, with zero derivative securities remaining from that grant. The derivative summary provided for this filing does not list any additional option positions tied to this specific transaction.