X0508 4 2026-03-05 0001680062 ACM Research, Inc. ACMR 0001779777 Feng Lisa C/O ACM RESEARCH, INC. 42307 OSGOOD ROAD, SUITE I FREMONT CA 94539 true See remarks true Class A Common Stock 2026-03-05 4 M 0 15000 4.55 A 65001 D Class A Common Stock 2026-03-05 4 S 0 8050 49.81 D 56951 D Class A Common Stock 2026-03-05 4 S 0 6950 50.24 D 50001 D Class A Common Stock 2026-03-06 4 M 0 15000 4.55 A 65001 D Class A Common Stock 2026-03-06 4 S 0 14800 46.07 D 50201 D Class A Common Stock 2026-03-06 4 S 0 200 46.58 D 50001 D Stock Option 4.55 2026-03-05 4 M 0 15000 0 D 2029-11-03 Class A Common Stock 15000 0 D Stock Option 4.55 2026-03-06 4 M 0 15000 0 D 2029-11-03 Class A Common Stock 15000 0 D The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 2, 2025. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $49.16 to $50.06, 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), (4) and (5) 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 $50.16 to $50.54, inclusive. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $45.51 to $46.48, inclusive. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $46.52 to $46.63, inclusive. The option is fully vested and exercisable. Chief Financial Officer of ACM Research (Shanghai), Inc., a subsidiary of the Issuer /s/ Mark McKechnie, Attorney-in-Fact for Lisa Feng 2026-03-09