X0508 4 2025-02-06 0001680062 ACM Research, Inc. ACMR 0001721279 Cheav Sotheara C/O ACM RESEARCH, INC. 42307 OSGOOD ROAD, SUITE I FREMONT CA 94539 true See remarks true Class A Common Stock 2025-02-06 4 M 0 10000 13.89 A 110002 D Class A Common Stock 2025-02-06 4 M 0 12598 13.89 A 122600 D Class A Common Stock 2025-02-06 4 S 0 22598 23 D 100002 D Stock Option 13.89 2025-02-06 4 M 0 10000 0 D 2033-08-09 Class A Common Stock 10000 90000 D Stock Option 13.89 2025-02-06 4 M 0 12598 0 D 2033-08-09 Class A Common Stock 12598 77402 D On February 6, 2025, the reporting person exercised a previously issued stock option to purchase 10,000 shares of Class A Common Stock of the Issuer. On February 6, 2025, the reporting person exercised a previously issued stock option to purchase 12,598 shares of Class A Common Stock of the Issuer. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 13, 2024. The option will vest and become exercisable as to 25,000 shares on August 09, 2024 and the remaining 75,000 shares will vest and become exercisable in equal monthly installments over the following 36 months, subject to continued service through each vesting date. Senior Vice President, Manufacturing of ACM Research (Shanghai), Inc., a subsidiary of the Issuer. /s/ Mark McKechnie, Attorney-in-Fact for Sotheara Cheav 2025-02-10