UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 27, 2026 ACM Research, Inc. (Exact Name of Registrant as Specified in its Charter) (State or Other Jurisdiction of Delaware 001-38273 94-3290283 (Commission File Number) (IRS Employer Identification No.) 42307 Osgood Road, Suite I Fremont, California 94539 (Address of Principal Executive ...