SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
Jun. 30, 2026
Accounting Policies [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The Company’s condensed consolidated financial statements include the accounts of ACM and its subsidiaries. ACM’s subsidiaries are those entities in which ACM, directly or indirectly, controls a majority of the voting power. All significant intercompany transactions and balances have been eliminated upon consolidation. The accompanying condensed consolidated financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and the rules and regulations of the Securities and Exchange Commission (the “SEC”) for reporting on Form 10-Q. Accordingly, they do not include all the information and footnotes required by GAAP for complete financial statements. The accompanying condensed consolidated financial statements should be read in conjunction with the historical consolidated financial statements of the Company for the year ended December 31, 2025 included in ACM’s 2025 Annual Report on Form 10-K. The accompanying condensed consolidated financial statements are unaudited. In the opinion of management, these unaudited condensed consolidated financial statements of the Company reflect all adjustments that are necessary for a fair presentation of the Company’s financial position and results of operations. Such adjustments are of a normal recurring nature, unless otherwise noted. The condensed consolidated balance sheet as of June 30, 2026 and the condensed consolidated results of operations for the three and six months ended June 30, 2026 are not necessarily indicative of the results to be expected for any future period.
Use of Estimates	Use of Estimates The preparation of the condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the balance sheet date and the reported revenues and expenses during the reported period in the condensed consolidated financial statements and accompanying notes. The Company’s significant accounting estimates and assumptions include, but are not limited to, those used for revenue recognition and deferred revenue, stock-based compensation arrangements, uncertain tax positions, warranty liabilities, allowance for credit losses, and inventory provision. Management evaluates these estimates and assumptions on a regular basis. Actual results could differ from those estimates and assumptions.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist of cash on hand, bank deposits that are unrestricted as to withdrawal and use, and highly liquid investments with an original maturity date of three months or less at the date of purchase. At times, cash deposits may exceed government-insured limits. Cash held in the U.S. exceeds the Federal Deposit Insurance Corporation insurance limits and is subject to risk of loss. No losses have been experienced to date. Cash amounts held in mainland China are subject to a series of risk control regulatory standards from mainland China bank regulatory authorities. ACM’s subsidiaries in mainland China are required to obtain approval from the State Administration of Foreign Exchange (“SAFE”) to transfer funds into or out of mainland China. SAFE requires a valid agreement to approve the transfers, which are processed through a bank. Other than these mainland China foreign exchange restrictions, ACM’s subsidiaries in mainland China are not subject to any restrictions and limitations on its ability to transfer funds to ACM or among our other subsidiaries. However, cash held in mainland China does exceed applicable insurance limits and is subject to risk of loss, although no such losses have been experienced to date.
Time Deposits	Time Deposits Time deposits are denominated in Chinese Renminbi (“RMB”) and U.S. dollars and deposited with banks in mainland China with fixed terms and interest rates and cannot be withdrawn before maturity. These deposits are presented as short- term deposits in the condensed consolidated financial statements based on their expected time of collection. They are also subject to the risk control regulatory standards described above upon maturity.
Restricted Cash	Restricted Cash All of the Company's restricted cash was held by financial institutions located in Mainland China, Hong Kong and South Korea, and mainly represents cash secured to guarantee delivery of tools.
Financial Instruments	Financial Instruments The Company periodically invests in equity and debt securities, and maintains an investment portfolio of various holdings, types, and maturities. For equity investments that do not have a readily determinable fair value, the Company classifies them as long-term investments, and records them using either: 1) the measurement alternative which measures the equity investments at cost minus impairment, if any, plus or minus changes resulting from qualifying observable price changes; or 2) the equity method whereby the Company recognizes its proportional share of the income or loss from the equity method investment. For equity investments that have a readily determinable fair value, the Company classifies them as short-term investments, and records them at fair market value on a recurring basis based upon quoted market prices. Realized and unrealized gains resulting from application of the measurement alternative, the impact of the application of the equity method to the Company’s equity investments, and recognition of changes in fair market value, as applicable, are recorded in non-operating income or loss in the condensed consolidated statements of comprehensive income. The Company’s investments in debt securities have been classified as available-for-sale securities. The Company classifies its debt securities as either short-term or long-term based on each instrument’s underlying contractual maturity date. Unrealized gains on debt securities classified as available-for-sale are recognized in accumulated other comprehensive income in the condensed consolidated balance sheets.
Fair Value Measurement	Fair Value Measurement The Company’s fair value measurements and hierarchy are consistent with those disclosed in the Company’s Annual Report on Form 10‑K for the year ended December 31, 2025. The Company’s financial instruments primarily include its cash, cash equivalents, restricted cash, short-term and long-term deposits, short-term and long-term investments, other receivables, accounts receivable, accounts payable, and short-term and long-term borrowings. The estimated fair value of cash and cash equivalents, restricted cash, short-term time deposits, accounts receivable, other receivables, accounts payable, and short-term borrowings approximate their respective carrying value due to the short period of time to their maturities. All transfers between fair value hierarchy levels are recognized by the Company at the end of each reporting period. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an investment’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement in its entirety, requires judgment and considers factors specific to the investment. The inputs or methodology used for valuing financial instruments are not necessarily an indication of the risks associated with investment in those instruments. Refer to note 9 for fair value information related to the Company’s outstanding long-term borrowings as of June 30, 2026 and December 31, 2025. The Company did not have any assets and liabilities measured at fair value on a non-recurring basis as of June 30, 2026 and December 31, 2025.
Basic and Diluted Net Income per Share of Common Stock	ACM Research is authorized to issue Class A and Class B common stock. The two classes of common stock are substantially identical in all material respects, except for voting rights. The net income per share of common stock attributable to each class is the same under the “two-class” method. As such, the two classes of common stock have been presented on a combined basis in the condensed consolidated statements of comprehensive income and in the above computation of net income per share of common stock. ACM did not have any participating securities outstanding during the three and six months ended June 30, 2026 and 2025. Diluted net income per share of common stock reflects the potential dilution from securities, such as stock options that could share in ACM Research’s earnings. Certain potentially dilutive securities were excluded from the net income per share calculation because the impact would be anti-dilutive. The number of potentially dilutive shares that were not included in the calculation of diluted net income per share in the periods presented where their inclusion would be anti-dilutive were stock options exercisable into shares of the Company’s common stock of 35,086 and 58,456 for the three and six months ended June 30, 2026, respectively and 1,338,186 and 1,321,311 for the three and six months ended June 30, 2025, respectively.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to credit risk consist principally of cash and cash equivalents, restricted cash, time deposits, and accounts receivable. The Company deposits and invests its cash with financial institutions that management believes are creditworthy. The Company is potentially subject to concentrations of credit risks in its revenue and accounts receivable. •Revenue concentration. For the three months ended June 30, 2026 and 2025, three customers accounted for 43.5% and four customers accounted for 66.5% of revenue, respectively. For the six months ended June 30, 2026 and 2025, one customer accounted for 12.7% and three customers accounted for 49.9% of revenue, respectively. •Accounts receivable concentration. As of June 30, 2026 and December 31, 2025, four customers accounted for 52.4% and four customers accounted for 62.2%, respectively, of the Company’s accounts receivables. The Company believes that the receivable balances from these largest customers do not represent a significant credit risk based on past collection experience.
Recently Issued Accounting Pronouncements Not Yet Adopted	Recently issued accounting pronouncements not yet adopted In December 2024, the FASB issued ASU 2024-03: Income Statement--Reporting Comprehensive Income--Expense Disaggregation Disclosures (Subtopic 220-40), which requires additional disclosures about specific types of expenses included in the expense captions presented on the face of the income statement as well as disclosures about selling expenses. In January 2025, the FASB issued ASU 2025-01, which clarifies the effective date of ASU 2024-03. ASU 2024-03 is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. This ASU should be applied prospectively with the option to apply the standard retrospectively. The Company is currently evaluating the provisions of this ASU. In December 2025, the FASB issued ASU 2025-10 – Government Grants which establishes guidance on the recognition, measurement, and presentation of government grants received by business entities. The new guidance leverages the principles in the accounting framework for government assistance in International Accounting Standard 20 – Accounting for Government Grants and Disclosure of Government Assistance. This ASU is effective for interim reporting periods within annual reporting periods beginning after December 15, 2028 and interim reporting periods within those annual periods. This ASU may be applied prospectively or retrospectively to any or all periods presented and early adoption of this ASU is permitted. The Company is currently evaluating the provisions of this ASU.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)

6 Months Ended

Jun. 30, 2026

Basis of Presentation and Principles of Consolidation

The Company’s condensed consolidated financial statements include the accounts of ACM and its subsidiaries. ACM’s subsidiaries are those entities in which ACM, directly or indirectly, controls a majority of the voting power. All significant intercompany transactions and balances have been eliminated upon consolidation.

The accompanying condensed consolidated financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and the rules and regulations of the Securities and Exchange Commission (the “SEC”) for reporting on Form 10-Q. Accordingly, they do not include all the information and footnotes required by GAAP for complete financial statements. The accompanying condensed consolidated financial statements should be read in conjunction with the historical consolidated financial statements of the Company for the year ended December 31, 2025 included in ACM’s 2025 Annual Report on Form 10-K.

The accompanying condensed consolidated financial statements are unaudited. In the opinion of management, these unaudited condensed consolidated financial statements of the Company reflect all adjustments that are necessary for a fair presentation of the Company’s financial position and results of operations. Such adjustments are of a normal recurring nature, unless otherwise noted. The condensed consolidated balance sheet as of June 30, 2026 and the condensed consolidated results of operations for the three and six months ended June 30, 2026 are not necessarily indicative of the results to be expected for any future period.

Use of Estimates

The preparation of the condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the balance sheet date and the reported revenues and expenses during the reported period in the condensed consolidated financial statements and accompanying notes. The Company’s significant accounting estimates and assumptions include, but are not limited to, those used for revenue recognition and deferred revenue, stock-based compensation arrangements, uncertain tax positions, warranty liabilities, allowance for credit losses, and inventory provision.

Management evaluates these estimates and assumptions on a regular basis. Actual results could differ from those estimates and assumptions.

Cash and Cash Equivalents

Cash and cash equivalents consist of cash on hand, bank deposits that are unrestricted as to withdrawal and use, and highly liquid investments with an original maturity date of three months or less at the date of purchase. At times, cash deposits may exceed government-insured limits.

Cash held in the U.S. exceeds the Federal Deposit Insurance Corporation insurance limits and is subject to risk of loss. No losses have been experienced to date.

Cash amounts held in mainland China are subject to a series of risk control regulatory standards from mainland China bank regulatory authorities. ACM’s subsidiaries in mainland China are required to obtain approval from the State Administration of Foreign Exchange (“SAFE”) to transfer funds into or out of mainland China. SAFE requires a valid agreement to approve the transfers, which are processed through a bank. Other than these mainland China foreign exchange restrictions, ACM’s subsidiaries in mainland China are not subject to any restrictions and limitations on its ability to transfer funds to ACM or among our other subsidiaries. However, cash held in mainland China does exceed applicable insurance limits and is subject to risk of loss, although no such losses have been experienced to date.

Time Deposits

Time deposits are denominated in Chinese Renminbi (“RMB”) and U.S. dollars and deposited with banks in mainland China with fixed terms and interest rates and cannot be withdrawn before maturity. These deposits are presented as short-

term deposits in the condensed consolidated financial statements based on their expected time of collection. They are also subject to the risk control regulatory standards described above upon maturity.

Restricted Cash

All of the Company's restricted cash was held by financial institutions located in Mainland China, Hong Kong and South Korea, and mainly represents cash secured to guarantee delivery of tools.

Financial Instruments

The Company periodically invests in equity and debt securities, and maintains an investment portfolio of various holdings, types, and maturities. For equity investments that do not have a readily determinable fair value, the Company classifies them as long-term investments, and records them using either: 1) the measurement alternative which measures the equity investments at cost minus impairment, if any, plus or minus changes resulting from qualifying observable price changes; or 2) the equity method whereby the Company recognizes its proportional share of the income or loss from the equity method investment. For equity investments that have a readily determinable fair value, the Company classifies them as short-term investments, and records them at fair market value on a recurring basis based upon quoted market prices. Realized and unrealized gains resulting from application of the measurement alternative, the impact of the application of the equity method to the Company’s equity investments, and recognition of changes in fair market value, as applicable, are recorded in non-operating income or loss in the condensed consolidated statements of comprehensive income.

The Company’s investments in debt securities have been classified as available-for-sale securities. The Company classifies its debt securities as either short-term or long-term based on each instrument’s underlying contractual maturity date. Unrealized gains on debt securities classified as available-for-sale are recognized in accumulated other comprehensive income in the condensed consolidated balance sheets.

Fair Value Measurement

The Company’s fair value measurements and hierarchy are consistent with those disclosed in the Company’s Annual Report on Form 10‑K for the year ended December 31, 2025.

The Company’s financial instruments primarily include its cash, cash equivalents, restricted cash, short-term and long-term deposits, short-term and long-term investments, other receivables, accounts receivable, accounts payable, and short-term and long-term borrowings. The estimated fair value of cash and cash equivalents, restricted cash, short-term time deposits, accounts receivable, other receivables, accounts payable, and short-term borrowings approximate their respective carrying value due to the short period of time to their maturities.

All transfers between fair value hierarchy levels are recognized by the Company at the end of each reporting period. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an investment’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement in its entirety, requires judgment and considers factors specific to the investment. The inputs or methodology used for valuing financial instruments are not necessarily an indication of the risks associated with investment in those instruments.

Refer to note 9 for fair value information related to the Company’s outstanding long-term borrowings as of June 30, 2026 and December 31, 2025. The Company did not have any assets and liabilities measured at fair value on a non-recurring basis as of June 30, 2026 and December 31, 2025.

Basic and Diluted Net Income per Share of Common Stock

ACM Research is authorized to issue Class A and Class B common stock. The two classes of common stock are substantially identical in all material respects, except for voting rights. The net income per share of common stock attributable to each class is the same under the “two-class” method. As such, the two classes of common stock have been presented on a combined basis in the condensed consolidated statements of comprehensive income and in the above computation of net income per share of common stock. ACM did not have any participating securities outstanding during the three and six months ended June 30, 2026 and 2025.

Diluted net income per share of common stock reflects the potential dilution from securities, such as stock options that could share in ACM Research’s earnings. Certain potentially dilutive securities were excluded from the net income per share calculation because the impact would be anti-dilutive. The number of potentially dilutive shares that were not included in the calculation of diluted net income per share in the periods presented where their inclusion would be anti-dilutive were stock options exercisable into shares of the Company’s common stock of 35,086 and 58,456 for the three and six months ended June 30, 2026, respectively and 1,338,186 and 1,321,311 for the three and six months ended June 30, 2025, respectively.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to credit risk consist principally of cash and cash equivalents, restricted cash, time deposits, and accounts receivable. The Company deposits and invests its cash with financial institutions that management believes are creditworthy.

The Company is potentially subject to concentrations of credit risks in its revenue and accounts receivable.

•Revenue concentration. For the three months ended June 30, 2026 and 2025, three customers accounted for 43.5% and four customers accounted for 66.5% of revenue, respectively. For the six months ended June 30, 2026 and 2025, one customer accounted for 12.7% and three customers accounted for 49.9% of revenue, respectively.

•Accounts receivable concentration. As of June 30, 2026 and December 31, 2025, four customers accounted for 52.4% and four customers accounted for 62.2%, respectively, of the Company’s accounts receivables. The Company believes that the receivable balances from these largest customers do not represent a significant credit risk based on past collection experience.

Recently Issued Accounting Pronouncements Not Yet Adopted

Recently issued accounting pronouncements not yet adopted

In December 2024, the FASB issued ASU 2024-03: Income Statement--Reporting Comprehensive Income--Expense Disaggregation Disclosures (Subtopic 220-40), which requires additional disclosures about specific types of expenses included in the expense captions presented on the face of the income statement as well as disclosures about selling expenses. In January 2025, the FASB issued ASU 2025-01, which clarifies the effective date of ASU 2024-03. ASU 2024-03 is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. This ASU should be applied prospectively with the option to apply the standard retrospectively. The Company is currently evaluating the provisions of this ASU.

In December 2025, the FASB issued ASU 2025-10 – Government Grants which establishes guidance on the recognition, measurement, and presentation of government grants received by business entities. The new guidance leverages the principles in the accounting framework for government assistance in International Accounting Standard 20 – Accounting for Government Grants and Disclosure of Government Assistance. This ASU is effective for interim reporting periods within annual reporting periods beginning after December 15, 2028 and interim reporting periods within those annual periods. This ASU may be applied prospectively or retrospectively to any or all periods presented and early adoption of this ASU is permitted. The Company is currently evaluating the provisions of this ASU.