X0306 4 2019-08-20 0001680062 ACM Research, Inc. ACMR 0001721580 Wang David H C/O ACM RESEARCH, INC. 42307 OSGOOD ROAD, SUITE I FREMONT CA 94539 true true true See Remarks Class A Common Stock 2019-08-20 4 M false 30000 0.75 A 196667 D Class A Common Stock 15279 I By Sophia Wang, daughter of David H. Wang Class A Common Stock 60000 I By David Hui Wang and Jing Chen Family Irrevocable Trust for Wang Children Class A Common Stock 206667 I By Wang-Chen Family Living Trust Stock Option 0.75 2019-08-20 4 M false 30000 0 D 2021-05-01 Class A Common Stock 30000 103334 D On August 20, 2019, the reporting person exercised previously issued stock options to purchase 30,000 shares of Class A Common Stock of the Issuer. The option is fully vested and exercisable. Chief Executive Officer, President and Director /s/ Mark L. Johnson, Attorney-in-Fact for David H. Wang 2019-08-21