What changed in this filing

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Item 9A. Controls and Procedures

2026-02-27 compared with 2025-03-03 · 49 added, 24 removed, 159 unchanged (31% of the section changed)

2 unchanged sentences

Our management, with the participation of our Chief Executive Officer and 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 Annual Report on Form 10-K.

Based on this evaluation, our Chief Executive Officer and Chief Financial Officer concluded that, as of December 31, 2024, our disclosure controls and procedures are designed at a reasonable assurance level and are 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, and that such information is accumulated and communicated to our management, including our Chief Executive Officer and Chief Financial Officer, as appropriate, to allow timely decisions regarding required disclosure.

Based on this evaluation, and due to the finding of the material weakness described below, our Chief Executive Officer and Chief Financial Officer concluded that, as of December 31, 2025, 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.

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

Management ’ s Report on Internal Control over Financial Reporting

1 unchanged sentence

Our management conducted an evaluation of the effectiveness of our internal control over financial reporting based on the framework in Internal Control—Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission.

Based on this evaluation, management concluded that our internal control over financial reporting was effective as of December 31, 2024.

Management reviewed the results of its assessment with our Audit Committee.

A material weakness is a deficiency, or a combination of deficiencies, in internal control over financial reporting, such that there is a reasonable possibility that a material misstatement of our annual or interim consolidated financial statements will not be prevented or detected on a timely basis.

As of December 31, 2025, we identified a material weakness in our internal control over financial reporting.

During the year-end financial reporting process for fiscal year 2025, the 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 and 2024.

We have developed a remediation plan for this material weakness, which is described below.

As further described in Note 2 and Note 17 to the Consolidated Financial Statements, the identified material weakness resulted in the misstatement of deferred income taxes and income tax benefit, net for the fiscal year ended December 31, 2024.

Ernst & Young LLP independently assessed the effectiveness of our internal control over financial reporting, as stated in the firm’s attestation report, which appears in Part II, Item 8 of this Annual Report on Form 10-K.

Remediation of Previously Disclosed Material Weakness

As disclosed in Item 9A Controls and Procedures in our Annual Report on Form 10-K for the year ended December 31, 2023, a material weakness was identified in internal control over financial reporting within the Company’s demand forecast process regarding excess and obsolete inventory.

During 2024, management completed the implementation of measures designed to ensure the remediation of control deficiencies contributing to the material weakness, including:

Improved the documentation of our review procedures, forecast analysis and management judgments;

Amended inventory provision spreadsheet formats to include procedural checklists, additional columns and color coding to delineate specific parts and products before and after review, set dollar thresholds for reserve requirements, and added a worksheet for management review comments;

Expanded review procedures for inventory reserve calculations and improved reconciliations between the inventory demand forecast and our financial system.

Management has determined, through testing of our internal controls and procedures, that the remediation measures discussed above were effectively designed and operated effectively for a sufficient period of time to allow us to conclude that the material weakness had been remediated as of December 31, 2024.

Management has been implementing and continues to implement measures designed to ensure that control deficiencies contributing to the material weakness are remediated, such that these controls are designed, implemented, and operating effectively.

These remediation actions are ongoing and include or are expected to include:

incorporation of a comprehensive local tax computation process, for material subsidiaries, into the worldwide tax computation process;

incorporation of documentation to monitor ongoing international tax developments, inclusive of involving the correct level of technical expertise;

improved documentation of the deferred tax review checklist including key aspects of local taxation.

As we continue to evaluate and work to improve our internal control over financial reporting, we may decide to take additional measures to address this identified deficiency or modify the remediation plans described above.

We believe that these actions will remediate the material weakness, 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 believes the foregoing plans will effectively remediate the deficiency constituting the material weakness and believes that the remediation of this material weakness (including necessary testing) will be completed during 2026.

However, there can be no assurance as to when such remediation will be completed.

As the remediation plan is implemented, management may take additional measures or modify the remediation plan elements described above.

Changes in Internal Control over Financial Reporting

Other than the remediation of the previously disclosed material weakness as described above, there were no changes in our internal control over financial reporting that occurred during the quarter ended December 31, 2024, that would have materially affected, or were reasonably likely to materially affect, our internal control over financial reporting.

Except for the 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 December 31, 2025, 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

10 unchanged sentences

Plan Duration

Intended Sale Amount (in shares)

Carintia Martinez , Director

Intended Sale Amount

Deming Xiao , Executive Vice President, Global Operations

November 13, 2025

Through November 13, 2026

During the three months ended December 31, 2024, no trading plans intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) were modified or terminated, and no other written trading arrangements that are not intended to qualify for the Rule 10b5-1(c) affirmative defense were adopted, modified, or terminated.

Maurice Sciammas , Executive Vice President, Worldwide Sales and Marketing

November 24, 2025

Through December 31, 2026

Saria Tseng , Executive Vice President, Strategic Corporate Development, General Counsel and Corporate Secretary

November 28, 2025

Through November 27, 2026

The following table summarizes the termination of trading plans intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) during the three months ended December 31, 2025:

Name and Title

Termination Date

Original Plan Duration

Intended Sale Amount

Saria Tseng , Executive Vice President, Strategic Corporate Development, General Counsel and Corporate Secretary

November 17, 2025

Through December 31, 2025

During the three months ended December 31, 2025, no trading plans intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) were modified, and no other written trading arrangements that are not intended to qualify for the Rule 10b5-1(c) affirmative defense were adopted, modified, or terminated.

Disclosure Regarding Foreign Jurisdictions that Prevent Inspections

4 unchanged sentences

Executive Compensation

The information required by this item will be set forth under the caption “Executive Officer Compensation” in the Company’s Proxy Statement for the 2025 Annual Meeting, and is incorporated herein by reference.

The information required by this item will be set forth under the caption “Named Executive Officer Compensation” in the Company’s Proxy Statement for the 2026 Annual Meeting, and is incorporated herein by reference.

Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

1 unchanged sentence

Certain Relationships and Related Transactions, and Director Independence

The information required by this item will be set forth under the captions “Certain Relationships and Related Transactions” and “Election of Directors” in the Company’s Proxy Statement for the 2025 Annual Meeting, and is incorporated herein by reference.

The information required by this item will be set forth under the captions “Certain Relationships and Related Transactions” and “Proposal One - Election of Directors” in the Company’s Proxy Statement for the 2026 Annual Meeting, and is incorporated herein by reference.

Principal Accountant Fees and Services

12 unchanged sentences

All schedules have been omitted because they are not required, not applicable, or the information required is otherwise included in the consolidated financial statements or notes thereto.

Amended and Restated Certificate of Incorporation.

Amended and Restated Bylaws of Monolithic Power Systems, Inc., effective April 26, 2022.

Amended and Restated Certificate of Incorporation of Monolithic Power Systems, Inc., effective June 12, 2025.

Amended and Restated Bylaws of Monolithic Power Systems, Inc., effective November 19, 2025.

Description of the Registrant ’ s Securities Registered Pursuant to Section 12 of the Securities Exchange Act of 1934.

43 unchanged sentences

This exhibit shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 or otherwise subject to the liabilities of that Section, nor shall it be deemed incorporated by reference in any filings under the Securities Act of 1933 or the Securities Exchange Act of 1934, whether made before or after the date hereof and irrespective of any general incorporation language in any filings.

Incorporated by reference to Exhibit 3.2 of the Registrant’s Registration Statement on Form S-1/A (Registration No.

333-117327), filed with the Securities and Exchange Commission on November 15, 2004.

Incorporated by reference to Exhibit 3.1 of the Registrant’s current report on Form 8-K (File No.

000-51026), filed with the Securities and Exchange Commission on April 27, 2022.

000-51026), filed with the Securities and Exchange Commission on June 16, 2025.

Incorporated by reference to Exhibit 3.1 of the Registrant’s current report on Form 8-K (File No.

000-51026), filed with the Securities and Exchange Commission on November 21, 2025.

Incorporated by reference to Exhibit 4.1 of the Registrant’s annual report on Form 10-K (File No.

42 unchanged sentences

Incorporated by reference to Exhibit 19.1 of the Registrant’s annual report on Form 10-K (File No.

000-51026), filed with the Securities and Exchange Commission on March 3, 2025.

Incorporated by reference to Exhibit 97.1 of the Registrant’s annual report on Form 10-K (File No.

000-51026), filed with the Securities and Exchange Commission on February 29, 2024.

2 unchanged sentences

MONOLITHIC POWER SYSTEMS, INC.

March 3, 2025

February 27, 2026

/s/ Michael Hsing

4 unchanged sentences

Bernie Blegen, jointly and severally, his or her attorneys-in-fact, each with the power of substitution, for him or her in any and all capacities, to sign any amendments to this report, and to file the same, with exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact, or his or her substitute or substitutes, may do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below on March 3, 2025 by the following persons on behalf of the registrant and in the capacities indicated:

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below on February 27, 2026 by the following persons on behalf of the registrant and in the capacities indicated:

/s/ Michael Hsing

2 unchanged sentences

Bernie Blegen

Chief Financial Officer (Principal Financial and Accounting Officer)

Executive Vice President and Chief Financial Officer (Principal Financial and Accounting Officer)

BERNIE BLEGEN

9 unchanged sentences

Compared sentence by sentence after normalising whitespace, quotation marks, case and digits, so re-formatting and restated figures do not read as changed language. Wording changes appear as one removal and one addition. The current filing and the prior one are authoritative.

What changed 10-K

Item 9A. Controls and Procedures