X0306 4 2022-03-09 0001680062 ACM Research, Inc. ACMR 0001721581 Dun Haiping C/O ACM RESEARCH, INC. 42307 OSGOOD ROAD, SUITE I FREMONT CA 94539 true Class A Common Stock 2022-03-09 4 M 0 12269 1.5 A 309568 D Class A Common Stock 2022-03-09 4 S 0 1200 80.48 D 308368 D Class A Common Stock 2022-03-09 4 S 0 8069 82.11 D 300299 D Class A Common Stock 2022-03-09 4 S 0 3000 82.66 D 297299 D Stock Option 1.5 2022-03-09 4 M 0 12269 0 D 2025-05-01 Class A Common Stock 231 231 D On March 9, 2022, the reporting person exercised a previously issued stock option to purchase 12,269 shares of Class A Common Stock of the Issuer. The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $79.99 to $80.82, 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 footnotes (3), (4), (5) and (6) to this Form 4. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $81.49 to $82.49, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $82.54 to $82.83, inclusive. The option vested and became exercisable as to 41,666 shares on May 1, 2016 and the remaining 125,001 shares vested and became exercisable in equal monthly installments over the following 36 months. /s/ Mark L. Johnson, Attorney-in-Fact for Haiping Dun 2022-03-11