Vanguard reports 5.31% stake in ACM Research

Vanguard Portfolio Management LLC, together with certain affiliated Vanguard entities, reports beneficial ownership of ACM Research Inc common stock.

Rhea-AI Filing Summary

Vanguard Portfolio Management LLC, together with certain affiliated Vanguard entities, reports beneficial ownership of ACM Research Inc common stock. As of June 30, 2026, Vanguard entities beneficially owned 3,405,116 shares of ACM Research Inc, representing 5.31% of the outstanding common stock.

Vanguard has sole voting power over 55,680 shares and sole dispositive power over 3,405,116 shares, with no shared voting or dispositive power reported. The holdings include securities held by Vanguard funds and other managed accounts over which these entities exercise voting and/or dispositive authority.

Key Figures

Beneficially owned shares: 3,405,116 shares Percent of class: 5.31% Sole voting power: 55,680 shares +2 more

5 metrics

Beneficially owned shares 3,405,116 shares ACM Research Inc common stock beneficially owned as of June 30, 2026

Percent of class 5.31% Portion of ACM Research Inc common stock beneficially owned

Sole voting power 55,680 shares Shares of ACM Research Inc over which Vanguard has sole voting power

Sole dispositive power 3,405,116 shares Shares of ACM Research Inc over which Vanguard has sole dispositive power

CUSIP 00108J109 CUSIP for ACM Research Inc common stock

Key Terms

beneficially owned, dispositive power, Schedule 13G, Investment Company Act of 1940

4 terms

beneficially owned financial

"reflects the securities beneficially owned, or deemed to be beneficially owned, by Vanguard"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

dispositive power financial

"sole power to dispose or to direct the disposition of: 3405116"

Dispositive power is the authority to decide the final outcome of an asset, legal claim, contract, or corporate action — in effect the power to dispose of or resolve something. For investors it matters because whoever holds that authority can determine who gets paid, who controls an asset or vote, and how risks and returns are allocated; think of it like holding the key that lets you lock in the winner or loser in a deal.

Schedule 13G regulatory

"In accordance with SEC Release No. 34-39538 ... reflected in this Schedule 13G"

A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.

Investment Company Act of 1940 regulatory

"investment companies registered under the Investment Company Act of 1940 and other managed accounts"

A U.S. federal law that sets the rulebook for pooled investment vehicles such as mutual funds, exchange-traded funds and similar money managers, requiring them to register with regulators, disclose holdings and fees, limit conflicts of interest, and follow governance standards. It matters to investors because these protections and transparency rules act like a referee and scoreboard, helping people compare funds, trust that managers follow fair practices, and spot hidden costs or risks.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many ACMR shares does Vanguard Portfolio Management report owning?

Vanguard Portfolio Management and related entities report 3,405,116 shares of ACM Research Inc common stock as beneficially owned as of June 30, 2026, according to their Schedule 13G filing.

What percentage of ACMR’s common stock is held by Vanguard Portfolio Management?

Vanguard Portfolio Management reports beneficial ownership of 5.31% of ACM Research Inc’s common stock, based on 3,405,116 shares held as of June 30, 2026.

What voting power does Vanguard Portfolio Management have over ACMR shares?

Vanguard Portfolio Management has sole voting power over 55,680 shares of ACM Research Inc and no shared voting power, indicating only a portion of its beneficially owned shares carry voting authority.

What dispositive power does Vanguard report over ACMR stock?

Vanguard Portfolio Management reports sole dispositive power over 3,405,116 shares of ACM Research Inc common stock and no shared dispositive power, meaning it can direct the sale or disposition of these shares.

Which Vanguard entities are included in the ACMR Schedule 13G filing?

The filing states that the reported holdings reflect securities beneficially owned by Vanguard Portfolio Management LLC and affiliates including Vanguard Fiduciary Trust Company and Vanguard Global Advisers, LLC.

Does any single Vanguard client own more than 5% of ACMR?

No. The filing explains that no single other person’s interest in the ACM Research Inc securities reported by Vanguard Portfolio Management exceeds 5% of the class.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 07/31/2026 - 10:58 AM Accepted by SEC EDGAR 07/31/2026 - 10:57 AM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

ACM Research Inc

(Name of Issuer)

Common Stock

(Title of Class of Securities)

00108J109

(CUSIP Number)

06/30/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 00108J109

1

Names of Reporting Persons

Vanguard Portfolio Management

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

PENNSYLVANIA

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 55,680.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 3,405,116.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,405,116.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.31 %

12

Type of Reporting Person (See Instructions)

IA

Comment for Type of Reporting Person: In accordance with SEC Release No. 34-39538 (January 12, 1998), this Schedule 13G reflects the securities beneficially owned, or deemed to be beneficially owned, by Vanguard Portfolio Management LLC and the following affiliates of Vanguard Portfolio Management LLC or business divisions of such affiliates: Vanguard Fiduciary Trust Company and Vanguard Global Advisers, LLC. This Schedule 13G includes securities held by Vanguard funds, or sleeves thereof, over which Vanguard Portfolio Management LLC exercises dispositive power, in addition to securities held by clients over which the affiliates or business divisions of such affiliates indicated above exercise dispositive and/or voting power. This Schedule 13G does not include securities, if any, beneficially owned by other subsidiaries or affiliates of Vanguard Portfolio Management LLC, or business divisions of such subsidiaries whose ownership of securities is disaggregated from that of the reporting business unit in accordance with such release.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: ACM Research Inc
(b)	Address of issuer's principal executive offices: 42307 Osgood Road, Unit 1, Fremont, CA, 94539
Item 2.
(a)	Name of person filing: Vanguard Portfolio Management
(b)	Address or principal business office or, if none, residence: 100 Vanguard Blvd,, Malvern, PA, 19355
(c)	Citizenship: PA
(d)	Title of class of securities: Common Stock
(e)	CUSIP Number(s): 00108J109
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 3405116
(b)	Percent of class: 5.31 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 55680
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 3405116
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. Vanguard Portfolio Management, including investment companies registered under the Investment Company Act of 1940 and other managed accounts, have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the securities reported herein.No one other person's interest in the securities reported herein is more than 5%.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Vanguard Portfolio Management

Signature:	My Trieu-Gatt
Name/Title:	Authorized Signatory, Head of Global Fund Administration
Date:	07/31/2026