Item 4. Controls and Procedures

Evaluation of Disclosure Controls and Procedures

Our management, with the participation of our Chief Executive Officer and Interim Chief Financial Officer, evaluated the effectiveness of our disclosure controls and procedures pursuant to Rule 13a-15(e) and Rule 15d-15(e) under the Securities Exchange Act of 1934 as of the end of the period covered by this Quarterly Report on Form 10-Q.

Based on this evaluation, and due to the finding of the material weakness described below, our Chief Executive Officer and Interim Chief Financial Officer concluded that, as of June 30, 2026, our disclosure controls and procedures were not effective to provide reasonable assurance that information we are required to disclose in reports that 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.

As previously reported in our Annual Report on Form 10-K for the year ended December 31, 2025, during the year-end financial reporting process for fiscal year 2025, a material weakness was identified in internal control over financial reporting related to the accounting for deferred income taxes. We engaged third-party tax service providers in connection with the original determination of the accounting for deferred income taxes associated with a one-time tax incentive granted by a certain foreign jurisdiction. Nevertheless, the internal controls in place with respect to the review of the calculation of deferred income taxes and the related income tax expense (benefit) were not designed appropriately or operating effectively as of December 31, 2025. The material weakness in internal control over financial reporting was not remediated as of June 30, 2026.

Notwithstanding the material weakness in internal control over financial reporting, management believes and has concluded that the condensed consolidated financial statements included in this Quarterly Report on Form 10-Q fairly present, in all material respects, our financial position, results of operations and cash flows for the periods presented in conformity with U.S. GAAP.

Ongoing Remediation of Previously Identified Material Weakness

With respect to the material weakness described above, management, under the oversight of the Audit Committee, has implemented measures designed to ensure that control deficiencies contributing to the material weakness are remediated, such that these controls are designed, implemented, and operating effectively. However, the material weakness will not be considered remediated until the applicable controls operate for a sufficient period of time and management has concluded, through testing, that these controls are operating effectively. Management expects to remediate the material weakness by the end of fiscal year 2026 and is monitoring the effectiveness of its remediation plan and will refine the plan as appropriate. However, there is no assurance as to when such remediation will be completed.

Changes in Internal Control over Financial Reporting

Except for the ongoing remediation measures related to the material weakness described above, there were no changes in our internal control over financial reporting that occurred during the quarter ended June 30, 2026, that would have materially affected, or were reasonably likely to materially affect, our internal control over financial reporting.

Limitations on Effectiveness of Controls and Procedures

In designing and evaluating the disclosure controls and procedures, management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving the desired control objectives. In addition, the design of disclosure controls and procedures must reflect the fact that there are resource constraints, and that management is required to apply its judgment in evaluating the benefits of possible controls and procedures relative to their costs.

PART II. OTHER INFORMATION

Item 1. Legal Proceedings

We are a party to actions and proceedings in the ordinary course of business, including challenges to the enforceability or validity of our intellectual property, claims that our products infringe on the intellectual property rights of others, and employment matters. We are also subject to litigation initiated by our stockholders. These proceedings often involve complex questions of fact and law and may require the expenditure of significant funds and the diversion of other resources to prosecute and defend. We defend ourselves vigorously against any such claims. Based on current information and management assessment, we do not believe that a material loss from known matters is probable as of June 30, 2026.

On February 4, 2025, a class action lawsuit was filed against us and certain of our executives. The lawsuit is captioned Waterford Twp. Gen. Emps. Ret. Sys. v. Monolithic Power Systems, Inc., et al., No. 25-cv-220 (W.D. Wash.) (the “Securities Action”) and alleges that we violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, and Rule 10b-5 promulgated thereunder, by making material misstatements or omissions relating to our business. We believe the lawsuit is meritless and currently intend to defend against it vigorously. Related to the Securities Action, shareholder derivative suits were also filed, against certain current – and former – directors and executives, alleging breaches of their fiduciary duties. One shareholder derivative suit has been filed under the caption Moore v. Hsing, et al., No. 26-cv-80720 (S.D. Fla.), filed on June 16, 2026, and the two other shareholder derivative suits have been consolidated under the caption Miller v. Hsing, et al., No. 25-cv-527 (W.D. Wash.), filed on March 26, 2025 (collectively, the “Derivative Litigation”). The Securities Action and Derivative Litigation seek unspecified amounts of damages and/or attorneys’ fees and other relief. The Derivative Litigation is stayed pending developments in the Securities Action.