8-K

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): October 1, 2025

MESA AIR GROUP, INC.

(Exact Name of Registrant as specified in its charter)

(602) 685-4000

(Registrant’s telephone number, including area code)

Not Applicable

(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:

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 3.01. Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing.

On October 1, 2025, Mesa Air Group, Inc. (the “Company” or “Mesa”) received a notification letter (the “Notice”) from the Listing Qualifications Department of The Nasdaq Stock Market LLC (“Nasdaq”) indicating that the Company was not in compliance with Listing Rule 5620(a) (the “Annual Shareholders Meeting Rule”), which requires that for continued listing on the Nasdaq Capital Market (“Nasdaq Capital Market”), the Company must hold an annual meeting of shareholders within 12 months of the end of the Company’s fiscal year end (based on the September 30^th^ fiscal year end, prior to Mesa’s recently announced change to a December 31 fiscal year end). The Notice is only a notification of deficiency, not of imminent delisting, and has no current effect on the listing or trading of the Company’s securities on Nasdaq Capital Market. Pursuant to Nasdaq Listing Rule 5810(c)(2)(G), the Notice states that the Company has 45 calendar days, or until November 17, 2025, to submit a plan to regain compliance with the Annual Shareholders Meeting Rule. The Company intends to submit a plan to regain compliance with the Annual Shareholders Meeting Rule within the required timeframe. After considering the Company’s plan, Nasdaq may grant the Company an exception of up to 180 calendar days from the prior fiscal year end, or until March 30, 2026, to regain compliance. There can be no assurance that Nasdaq will accept the Company’s plan or that the Company will be able to regain compliance with the Annual Shareholders Meeting Requirement or maintain compliance with any other Nasdaq requirement in the future.

Mesa has delayed the holding of its annual meeting of stockholders due to the pendency of its previously-announced proposed merger with Republic Airways Holdings Inc. (“Republic Airways”) under the Agreement, Plan of Conversion and Plan of Merger, dated as of April 4, 2025, pursuant to which Republic Airways will merge with and into Mesa (the “Merger”), with Mesa continuing as the surviving corporation following the Merger (and subsequently renamed “Republic Airways Holdings Inc.”). The Company expects the Merger to close in the fourth quarter of 2025, subject to approval by Mesa’s stockholders and the satisfaction of other customary closing conditions. Mesa has called a special meeting of its stockholders for the purpose of voting on the adoption of the merger agreement and certain other proposals to be held on November 17, 2025.

No Offer or Solicitation

This Current Report on Form 8-K is for informational purposes only and is not intended to and does not constitute, or form a part of, a proxy statement or solicitation of a proxy, consent or authorization with respect to any securities or in respect of the proposed transaction and is not intended to and does not constitute an offer to sell or the solicitation of an offer to buy, sell or solicit any securities or any proxy, vote or approval, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. No offering of securities shall be made, except by means of a prospectus meeting the requirements of Section 10 of the Securities Act of 1933, as amended (the “Securities Act”).

Additional Information and Where to Find It

This Current Report on Form 8-K relates to the proposed merger involving Mesa and Republic Airways. In connection with the proposed transaction, Mesa has filed with the Securities and Exchange Commission (“SEC”) a Form S-4/S-1 Registration Statement, which has been declared effective by the SEC and includes a proxy statement on Schedule 14A and prospectus (the “proxy statement/prospectus”). Promptly after filing the proxy statement/prospectus with the SEC on October 2, 2025, Mesa has commenced mailing of the definitive proxy statement/prospectus and a proxy card to each stockholder entitled to vote at the special meeting relating to the proposed transaction. INVESTORS AND SECURITY HOLDERS OF MESA ARE URGED TO READ THE PROXY STATEMENT/PROSPECTUS (INCLUDING ANY AMENDMENTS OR SUPPLEMENTS THERETO) AND ANY OTHER RELEVANT DOCUMENTS IN CONNECTION WITH THE TRANSACTION THAT MESA FILES WITH THE SEC WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT THE PROPOSED TRANSACTION. The proxy statement/prospectus and any other documents filed by Mesa with the SEC (when available) may be obtained free of charge at the SEC’s website at www.sec.gov or by accessing the Investor Relations section of Mesa’s website at https://investor.mesa-air.com/.

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 hereunto duly authorized.