UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the
Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): March 31, 2026

Capstone Green Energy Holdings, Inc.

(Exact name of registrant as specified in its charter)

(818) 734-5300

(Registrant’s telephone number, including area code)

N/A 

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

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

Indicate by check mark whether the Registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ¨

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. ¨

Item 5.03 Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year. 

 On March 31, 2026, Capstone Green Energy Holdings, Inc (the “Company”) filed the Certificate of Designation, Preferences and Rights for the purpose of designating and establishing the Series A Convertible Preferred Stock of the Company (the “Preferred Stock”) with the Secretary of State of the State of Delaware, which became effective upon filing. The terms and conditions of the Preferred Stock were described in the Company’s Current Report on Form 8-K filed on March 31, 2026, which description is incorporated herein by reference. A copy of the Certificate of Designation is attached hereto as Exhibit 3.1 and is incorporated herein by reference.

Item 7.01 Regulation FD.

On March 31, 2026, the Company issued a press release announcing the closing of its previously announced strategic investment, a copy of which is attached hereto as Exhibit 99.1 and is incorporated by reference herein. The information furnished in Exhibit 99.1 hereto shall not be considered “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be incorporated by reference into future filings by the Company under the Securities Act or under the Exchange Act, unless the Company expressly sets forth in such future filings that such information is to be considered “filed” or incorporated by reference therein.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits Index

Signatures

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.