Ultra Clean Holdings, Inc.

Evaluation of Disclosure Controls and Procedures

Under the supervision and with the participation of our management, including our chief executive officer and chief financial officer, we conducted an evaluation of the Company’s disclosure controls and procedures, as such term is defined in Rule 13a-15(e) under the Exchange Act. Disclosure controls and procedures are designed to ensure that information required to be disclosed by us in the reports we file or submit under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in the SEC’s rules and forms and that such information is accumulated and communicated to management, including the chief executive officer and chief financial officer, as appropriate, to allow timely decisions regarding required disclosure. Based upon this evaluation, our chief executive officer and our chief financial officer concluded the Company’s disclosure controls and procedures were effective as of December 26, 2025, the end of the period covered by this Annual Report on Form 10-K.

Management’s Report on Internal Control Over Financial Reporting

Management is responsible for establishing and maintaining adequate internal control over financial reporting. Internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external reporting purposes in accordance with generally accepted accounting principles.

Management of the Company has assessed the effectiveness of the Company’s internal control over financial reporting as of December 26, 2025 using the criteria described in Internal Control – Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). Based on this evaluation, management concluded that the Company’s internal control over financial reporting was effective as of December 26, 2025.

The effectiveness of the Company’s internal control over financial reporting as of December 26, 2025 has been audited by PricewaterhouseCoopers LLP, an independent registered public accounting firm, as stated in their report which appears under Item 8.

Remediation of Previously Reported Material Weaknesses

We previously disclosed material weaknesses in our internal control over financial reporting related to the following:

•The Company did not design and maintain effective controls relating to the: (i) sufficiency of processes related to identifying and analyzing risks to the achievement of objectives across the Company, (ii) sufficiency of competent personnel to analyze risks of material misstatement and develop internal control activities to support the achievement of the Company’s internal control objectives; and (iii) monitoring of control activities in accordance with established policies in a timely manner.

•These material weaknesses contributed to the following additional material weaknesses:

(a) The Company did not design and maintain effective information technology (“IT”) general controls for certain information systems that are relevant to the preparation of its consolidated financial statements. Specifically, for certain of the Fluid Solutions operating subsidiaries in the Products segment which have not been migrated to the Company’s primary ERP system, the Company did not design and maintain (i) program change management controls to ensure that IT program and data changes are identified, tested, authorized and implemented appropriately, and (ii) user access controls to ensure appropriate segregation of duties and to adequately restrict user and privileged access to appropriate company personnel.

(b) The Company did not design and maintain effective controls for certain other international operating subsidiaries in the Products segment. Specifically, the Company did not design and maintain effective segregation of duties controls across various business processes, including journal entries.

During the quarter ended December 26, 2025, we completed the following activities as part of remediating the material weaknesses:

•Hired additional compliance personnel to support our remediation efforts.

•Monitored the effective performance of internal controls under remediation.

•Delivered training programs designed to support our internal controls.

In response to the material weakness “(a)” management has taken the following actions:

•We migrated the Fluid Solutions operating subsidiaries to our primary ERP system in the third quarter of 2025, including the utilization of existing IT general controls of our primary ERP system leveraging standard user access controls to ensure appropriate segregation of duties that adequately restrict user access to our financial applications and data to appropriate company personnel.

In response to the material weakness “(b)” management has taken the following actions:

•During the third quarter of 2025, we began operating the previously designed and implemented controls over segregation of duties assessment to identify key conflicts, established policies and procedures to maintain effective segregation of duties, and identified and implemented mitigating controls for key conflicts identified for certain other international operating subsidiaries in the Products segment which have not been migrated to the Company’s primary ERP system.

During the quarter ended December 26, 2025, we completed our testing of both the design and operating effectiveness of these controls and have determined that controls operated for a sufficient period of time for management to conclude that these material weaknesses have been remediated as of December 26, 2025.

Changes in Internal Control Over Financial Reporting

There were no changes in our internal control over financial reporting during the fiscal fourth quarter ended December 26, 2025 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.