X0508 4 2025-09-17 0001680062 ACM Research, Inc. ACMR 0001721299 Liu Tracy C/O ACM RESEARCH, INC. 42307 OSGOOD ROAD, SUITE I FREMONT CA 94539 true true Class A Common Stock 2025-09-17 4 M 0 15000 1 A 125772 D Class A Common Stock 2025-09-17 4 S 0 15000 33 D 110772 D Stock Option 1 2025-09-17 4 M 0 15000 0 D 2026-12-27 Class A Common Stock 15000 60000 D On September 17, 2025, the reporting person exercised a previously issued stock option to purchase 15,000 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 March 6, 2025. The option is fully vested and exercisable. /s/ Mark McKechnie, Attorney-in-Fact for Tracy Liu 2025-09-19