X0609 4 2026-08-20 0001680062 ACM Research, Inc. ACMR 0001775007 McKechnie Mark false C/O ACM RESEARCH, INC. 42307 OSGOOD ROAD, SUITE I FREMONT CA 94539 true See Remarks true Class A Common Stock 2026-08-20 4 M 0 30199 19.49 A 31099 D Class A Common Stock 2026-08-20 4 M 0 25000 13.89 A 56099 D Class A Common Stock 2026-08-20 4 S 0 13625 76.34 D 42474 D Class A Common Stock 2026-08-20 4 S 0 30365 77.45 D 12109 D Class A Common Stock 2026-08-20 4 S 0 11209 77.89 D 900 D Stock Option 19.49 2026-08-20 4 M 0 30199 0 D 2032-08-11 Class A Common Stock 30199 31250 D Stock Option 13.89 2026-08-20 4 M 0 25000 0 D 2033-08-09 Class A Common Stock 25000 215000 D The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on May 21, 2026. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $75.76 to $76.68, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (2), (3), and (4) to this Form 4. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $76.81 to $77.79, inclusive. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $77.84 to $78.4, inclusive. The option is fully vested and exercisable. Chief Financial Officer and Treasurer /s/ Mark McKechnie 2026-08-21