X0306 4 2021-11-03 0001680062 ACM Research, Inc. ACMR 0001779777 Feng Lisa C/O ACM RESEARCH, INC. 42307 OSGOOD ROAD, SUITE I FREMONT CA 94539 true See remarks Class A Common Stock 2021-11-03 4 M 0 2437 5.6 A 16667 D Stock Option 5.6 2021-11-03 4 M 0 2437 0 D 2027-11-01 Class A Common Stock 2437 0 D On November 3, 2021, the reporting person exercised a previously issued stock option to purchase 2,437 shares of Class A Common Stock of the Issuer. The option vested and became exercisable as to 4,167 shares on August 15, 2018 and the remaining 12,500 shares vested and became exercisable in equal monthly installments over the following 36 months. Chief Financial Officer of ACM Research (Shanghai), Inc. /s/ Mark L. Johnson, Attorney-in-Fact for Lisa Feng 2021-11-05