X0306 4 2019-05-09 0001680062 ACM Research, Inc. ACMR 0001721279 Cheav Sotheara C/O ACM RESEARCH, INC. 42307 OSGOOD ROAD, SUITE I FREMONT CA 94539 true See remarks Class A Common Stock 2019-05-09 4 M false 10000 0.75 A 43334 D Stock Option 0.75 2019-05-09 4 M false 10000 0 D 2021-05-01 Class A Common Stock 10000 23334 D On May 9, 2019, the reporting person exercised previously issued stock options to purchase 10,000 shares of Class A Common Stock of the Issuer. The option is fully vested and exercisable. Vice President, Manufacturing of ACM Research (Shanghai), Inc., a subsidiary of the Issuer /s/ Mark L. Johnson, Attorney-in-Fact for Sotheara Cheav 2019-05-10