Ultra Clean Holdings, Inc.

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. On September 28, 2026, the Board of Directors (the “Board”) of Ultra Clean Holdings, Inc. (the “Company”) appointed Alexander Davern to serve as a member of the Board, effective September 28, 2026. Mr. Davern, age 60, is a former public-company chief executive officer and has more than 30 years of experience in global industrial technology businesses. He served at National Instruments Corporation from 1994 to 2020, including as Chief Executive Officer from 2017 to 2020, Chief Operating Officer from 2010 to 2016, and Chief Financial Officer from 1998 to 2010. Mr. Davern remained a director of National Instruments through its acquisition by Emerson Electric Co. in 2023. He currently serves as an independent director of Cirrus Logic, Inc., Computer Modelling Group Ltd. and Spectris plc. Mr. Davern holds a Bachelor of Commerce degree from University College Dublin and a diploma in professional accounting. Mr. Davern will receive compensation for his service as a director in accordance with the Company’s non-employee director compensation policy. In connection with his appointment, the Company expects that Mr. Davern and the Company will enter into the Company’s standard form of indemnification agreement, previously filed with the SEC. There are no arrangements or understandings between Mr. Davern and any other person pursuant to which he was selected as a director. Mr. Davern is not a party to any transaction with the Company that would require disclosure under Item 404(a) of Regulation S-K. On September 30, 2026, the Company issued a press release announcing Mr. Davern’s appointment to the Board. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K.