RICHARDSON ELECTRONICS, LTD.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 10-K

☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended May 30,2026

OR

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from__________ to

Commission File Number:0-12906

(Exact name of registrant as specified in its charter)

40W267 Keslinger Road, P.O. Box 393, LaFox, Illinois 60147-0393

(Address of principal executive offices)

Registrant’s telephone number, including area code: (630)208-2200

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.☐ Yes☒ No

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act☐ Yes☒ No

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.☒ Yes ☐ No

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).☒ Yes ☐ No

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.☒

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements.☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b). ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).☐ Yes☒ No

The aggregate market value of the registrant’s common stock held by non-affiliates of the registrant as of November 29, 2025 was approximately $126.2 million.

As of July 27, 2026, there were outstanding 12,656,822 shares of Common Stock, $0.05 par value and 2,035,671 shares of Class B Common Stock, $0.05 par value, which are convertible into Common Stock of the registrant on a one-for-one basis.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant’s Proxy Statement for the Annual Meeting of Stockholders scheduled to be held October 6, 2026, which will be filed pursuant to Regulation 14A, are incorporated by reference in Part III of this report. Except as specifically incorporated herein by reference, the above mentioned Proxy Statement is not deemed filed as part of this report.

Auditor Firm ID: 00243 Auditor Name: BDO USA, P.C. Auditor Location: Chicago, IL, USA

TABLE OF CONTENTS

Forward Looking Statements

Certain statements in this report may constitute “forward-looking” statements within the meaning of the Private Securities Litigation Reform Act of 1995. The terms “may,” “should,” “could,” “anticipate,” “believe,” “continues,” “estimate,” “expect,” “intend,” “objective,” “plan,” “potential,” “project,” and similar expressions are intended to identify forward-looking statements. These statements are not guarantees of future performance and involve risks, uncertainties and assumptions that are difficult to predict. These statements are based on management’s current expectations, intentions or beliefs and are subject to a number of factors, assumptions and uncertainties that could cause actual results to differ materially from those described in the forward-looking statements. Factors that could cause or contribute to such differences or that might otherwise impact the business include the risk factors set forth in Item 1A of this Form 10-K. We undertake no obligation to update any such factor or to publicly announce the results of any revisions to any forward-looking statements contained herein, whether as a result of new information, future events or otherwise.

In addition, while we do, from time to time, communicate with securities analysts, it is against our policy to disclose to them any material non-public information or other confidential commercial information. Accordingly, stockholders should not assume that we agree with any statement or report issued by any analyst irrespective of the content of the statement or report. Thus, to the extent that reports issued by securities analysts contain any projections, forecasts or opinions, such reports are not our responsibility.