X0609 4 2026-06-03 0001680062 ACM Research, Inc. ACMR 0001721580 Wang David H false C/O ACM RESEARCH, INC. 42307 OSGOOD ROAD, SUITE I FREMONT CA 94539 true true true See Remarks true Class A Common Stock 2026-06-03 4 M 0 60000 1 A 862708 D Class A Common Stock 2026-06-03 4 S 0 4300 87.57 D 858408 D Class A Common Stock 2026-06-03 4 S 0 6295 88.98 D 852113 D Class A Common Stock 2026-06-03 4 S 0 32450 89.84 D 819663 D Class A Common Stock 2026-06-03 4 S 0 9925 90.78 D 809738 D Class A Common Stock 2026-06-03 4 S 0 5843 92.38 D 803895 D Class A Common Stock 2026-06-03 4 S 0 1187 93.04 D 802708 D Class A Common Stock 2026-06-04 4 M 0 40002 1 A 842710 D Class A Common Stock 2026-06-04 4 S 0 2060 83.86 D 840650 D Class A Common Stock 2026-06-04 4 S 0 17543 85.11 D 823107 D Class A Common Stock 2026-06-04 4 S 0 10992 86.07 D 812115 D Class A Common Stock 2026-06-04 4 S 0 8581 87.13 D 803534 D Class A Common Stock 2026-06-04 4 S 0 826 87.91 D 802708 D Class A Common Stock 100002 I By Jing Chen, wife of David H. Wang Class A Common Stock 45837 I By Sophia Wang, daughter of David H. Wang Class A Common Stock 180000 I By David Hui Wang and Jing Chen Family Irrevocable Trust for Wang Children Class A Common Stock 620001 I By Wang-Chen Family Living Trust Stock Option 1 2026-06-03 4 M 0 60000 0 D 2026-12-27 Class A Common Stock 60000 310002 D Stock Option 1 2026-06-04 4 M 0 40002 0 D 2026-12-27 Class A Common Stock 40002 270000 D The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on November 29, 2024. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $87.22 to $88.04, 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), (5), (6), (7), (8), (9), (10), (11), and (12) 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 $88.24 to $89.22, inclusive. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $89.24 to $90.22, inclusive. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $90.24 to $91.22, inclusive. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $92.01 to $92.8, inclusive. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $93.02 to $93.39, inclusive. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $83.61 to $84.24, inclusive. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $84.62 to $85.6, inclusive. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $85.7 to $86.57, inclusive. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $86.73 to $87.66, inclusive. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $87.77 to $88.01, inclusive. The option is fully vested and exercisable. Chief Executive Officer, President and Director /s/ Mark McKechnie, Attorney-in-Fact for David H. Wang 2026-06-05