X0407 4 2023-07-03 0001680062 ACM Research, Inc. ACMR 0001779777 Feng Lisa C/O ACM RESEARCH, INC. 42307 OSGOOD ROAD, SUITE I FREMONT CA 94539 true See remarks false Class A Common Stock 2023-07-03 4 M 0 22500 1.77 A 72501 D Class A Common Stock 2023-07-03 4 S 0 22500 15 D 50001 D Stock Option 1.77 2023-07-03 4 M 0 22500 0 D 2028-01-24 Class A Common Stock 22500 0 D The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person. The option was fully vested and exercisable. Due to an administrative error, the reporting person's previous Form 4 filed on March 13, 2023 reflected an incorrect amount of zero for number of derivative securities beneficially owned following reported transaction(s) in Column 9 rather than 22,500. This filing corrects that error. Chief Financial Officer of ACM Research (Shanghai), Inc., a subsidiary of the Issuer /s/ Mark McKechnie, Attorney-in-Fact for Lisa Feng 2023-07-05