Harbor Diversified misses 10-K deadline after asset sale

Harbor Diversified, Inc. filed a Form 12b-25 notifying the SEC it cannot timely file its Annual Report on Form 10-K for the year ended December 31, 2025 because it requires additional time to finalize audited financial statements.

Rhea-AI Filing Summary

Harbor Diversified, Inc. filed a Form 12b-25 notifying the SEC it cannot timely file its Annual Report on Form 10-K for the year ended December 31, 2025 because it requires additional time to finalize audited financial statements. The delay reflects extended audit work tied to prior-period financial statement matters and the company’s sale of aviation assets, including membership interests in Air Wisconsin, completed on January 9, 2026. The company states it no longer has material operating assets or operating revenue following that disposition and anticipates significant changes in its financial condition and results of operations. The notification was signed April 1, 2026.

Positive

• None.

Negative

• Post-disposition non‑operating status: the company "does not have any material operating assets" and "is not engaged in any operating business," indicating a major change to the business model.
• Material financial impact expected: the company anticipates "significant changes in its financial condition and results of operations" for the period ended December 31, 2025.

Insights

Corporate Restructuring Advisor

Company reports post-disposition transition to non-operating status.

Harbor Diversified states it completed the Aviation Disposition on January 9, 2026 and "does not have any material operating assets" thereafter. That change transforms the company from an operating airline-related lessor/operator into an entity without operating revenue.

Key dependencies include completion of audited financials and outcomes of strategic-alternatives processes referenced in its filings. Subsequent filings should show how proceeds, liabilities, and any remaining cash are classified; timing is not specified in the provided excerpt.

Audit & SEC Reporting Specialist

Extended audit work and prior-period restatements/adjustments delayed the 10-K.

The company attributes the late filing to time spent finalizing financial statements and audit review related to prior Form 10-K (2023) and quarterly 10-Qs for 2024. Rule 12b-25 was used to request more time because the company cannot file "without unreasonable effort or expense."

Watch for the next filing to include finalized audited statements, disclosures on the Aviation Disposition, and reconciliations of prior-period adjustments or any going-concern or liquidity disclosures.

Key Figures

Form period end: December 31, 2025 Aviation Disposition completion: January 9, 2026 Form 8-K reference: January 16, 2026 +3 more

6 metrics

Form period end December 31, 2025 Annual Report on Form 10-K for the year ended

Aviation Disposition completion January 9, 2026 Date the sale and disposition of aviation assets was completed

Form 8-K reference January 16, 2026 Form 8-K filed with additional information on the Aviation Disposition

Form 12b-25 signature date April 1, 2026 Date notification was signed by CEO Christine R. Deister

Capacity Purchase Agreement date August 19, 2022 Date of the capacity purchase agreement previously terminated with American Airlines

Form 12b-25 expiry line September 30, 2028 Expires (document header)

Key Terms

Form 12b-25, Aviation Disposition, capacity purchase agreement, Form 8-K, +1 more

5 terms

Form 12b-25 regulatory

"This Form 12b-25 (Notification of Late Filing) is being filed by Harbor Diversified, Inc."

Form 12b-25 is a notice a publicly traded company files with the U.S. Securities and Exchange Commission when it cannot deliver a required periodic report (like a quarterly or annual financial report) on time. It explains the reason for the delay and gives the company a short, temporary window to finish the report without being marked as delinquent; investors watch it because late filings can signal accounting, operational, or control issues that may affect a company’s reliability and stock risk, much like a missed homework deadline can raise concerns about a student’s preparedness.

Aviation Disposition transactional

"the sale and disposition of the Company’s aviation assets, including its membership interests in Air Wisconsin"

capacity purchase agreement contractual

"termination of the capacity purchase agreement, dated August 19, 2022, previously entered into by and between the Company and American Airlines, Inc."

Form 8-K regulatory

"refer to Item 2.01 of the Company’s Current Report on Form 8-K filed with the Commission on January 16, 2026"

A Form 8-K is a report that companies file with the government to share important news quickly, such as changes in leadership, major business deals, or financial updates. It matters because it helps investors stay informed about significant events that could affect the company's value or stock price.

Rule 12b-25 regulatory

"to seek an extension of the filing deadline for its Annual Report pursuant to Rule 12b-25 under the Securities Exchange Act of 1934"

Rule 12b-25 is an SEC filing provision that lets a company notify regulators and the public that it cannot file a required periodic report (like a quarterly or annual report) on time and explains the reason for the delay. For investors, the notice is a formal heads-up that financial information will arrive late—similar to a company calling to say it will be late turning in homework—so it signals increased uncertainty and may affect trading and risk assessments until the filing is available.

FAQ

Why did Harbor Diversified (HRBR) file a Form 12b-25?

They could not timely complete audited financials. The company needs additional time to finalize the financial statements and complete the audit for the year ended December 31, 2025, citing extended audit work and related prior-period matters.

What major transaction affected HRBR’s ability to file its 2025 10-K?

Sale of aviation assets, including Air Wisconsin interests. Harbor Diversified completed the Aviation Disposition on January 9, 2026, which the company cites as a factor in the delayed 10-K.

Does Harbor Diversified still have operating revenue after the disposition?

No—company reports no operating revenue. The filing states after the Aviation Disposition the company "does not have any material operating assets" and "is not engaged in any operating business."

When was the Form 12b-25 signed for HRBR?

The notification was signed on April 1, 2026. The document is submitted to request additional time to file the Annual Report on Form 10-K for the year ended December 31, 2025.

Will HRBR’s financial condition meaningfully change for 2025 results?

Yes, the company anticipates significant changes. Harbor Diversified explicitly states it expects significant changes in financial condition and results for the period ended December 31, 2025 relative to 2024 due to the disposition and other actions.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 04/01/2026 - 05:10 PM Learn about SEC filing dates

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SEC FILE NUMBER
001-34584
CUSIP NUMBER
41150R102

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 12b-25

NOTIFICATION OF LATE FILING

(Check one):		☒ Form 10-K  ☐ Form 20-F  ☐ Form 11-K  ☐ Form 10-Q ☐ Form 10-D  ☐ Form N-CEN  ☐ Form N-CSR
		For Period Ended:  December 31, 2025
		☐ Transition Report on Form 10-K
		☐ Transition Report on Form 20-F
		☐ Transition Report on Form 11-K
		☐ Transition Report on Form 10-Q
		For the Transition Period Ended:

Read Instruction (on back page) Before Preparing Form. Please Print or Type.

Nothing in this form shall be construed to imply that the Commission has verified any information contained herein.

If the notification relates to a portion of the filing checked above, identify the Item(s) to which the notification relates:

Not applicable.

PART I — REGISTRANT INFORMATION

Harbor Diversified, Inc.

Full Name of Registrant

Former Name if Applicable

5601 W. Grande Market Drive, Suite C

Address of Principal Executive Office (Street and Number)

Appleton, WI 54913

City, State and Zip Code

PART II — RULES 12b-25(b) AND (c)

If the subject report could not be filed without unreasonable effort or expense and the registrant seeks relief pursuant to Rule 12b-25(b), the following should be completed. (Check box if appropriate)

☐		(a)		The reason described in reasonable detail in Part III of this form could not be eliminated without unreasonable effort or expense;
		(b)		The subject annual report, semi-annual report, transition report on Form 10-K, Form 20-F, Form 11-K, Form N-CEN or Form N-CSR, or portion thereof, will be filed on or before the fifteenth calendar day following the prescribed due date; or the subject quarterly report or transition report on Form 10-Q or subject distribution report on Form 10-D, or portion thereof, will be filed on or before the fifth calendar day following the prescribed due date; and
		(c)		The accountant’s statement or other exhibit required by Rule 12b-25(c) has been attached if applicable.

SEC 1344 (06-19) Persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.

PART III — NARRATIVE

State below in reasonable detail why Forms 10-K, 20-F, 11-K, 10-Q, 10-D, N-CEN, N-CSR, or the transition report or portion thereof, could not be filed within the prescribed time period.

This Form 12b-25 (Notification of Late Filing) is being filed by Harbor Diversified, Inc. (the “Company”) to seek an extension of the filing deadline for its Annual Report on Form 10-K for the year ended December 31, 2025 (the “Annual Report”) pursuant to Rule 12b-25 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”).

The Company has determined that it is unable to file the Annual Report by the prescribed due date without unreasonable effort or expense. The Company requires additional time to finalize the financial statements and complete the audit for the year ended December 31, 2025.

The delay in filing the Annual Report is a consequence of the considerable time and resources dedicated by the Company and its independent registered public accounting firm to complete certain items with respect to the preparation, audit and review of the Company’s financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2023, and the preparation and review of the Company’s financial statements included in its Quarterly Reports on Form 10-Q for the quarters ended March 31, 2024, June 30, 2024, and September 30, 2024. The delay is also the result of the considerable time and resources dedicated to the sale and disposition of the Company’s aviation assets, including its membership interests in Air Wisconsin, in a series of transactions that were completed on January 9, 2026 (the “Aviation Disposition”). For additional information regarding the Aviation Disposition, please refer to Item 2.01 of the Company’s Current Report on Form 8-K filed with the Commission on January 16, 2026 (the “Form 8-K”).

As a result, the Company does not expect to file the Annual Report within the 5-day extension period provided under Rule 12b-25 under the Exchange Act.

Cautionary Note Regarding Forward-Looking Statements

This Form 12b-25 contains forward-looking statements within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995, which statements are subject to considerable risks and uncertainties. These forward-looking statements include statements regarding the expected timing of the filing of the Annual Report. Forward-looking statements include all statements that are not solely historical facts and can be identified by terms such as “believe,” “anticipate,” “could,” “estimate,” “expect,” “may,” “should,” or similar expressions. Investors are cautioned not to place undue reliance on these forward-looking statements, which are subject to numerous risks and uncertainties that could cause actual results to differ materially from those expressed or implied by such statements, including the risks and uncertainties addressed under the heading “Risk Factors” and elsewhere in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023, the Quarterly Report on Form 10-Q for the quarter ended September 30, 2024, and the other filings the Company makes with the Commission from time to time. These forward-looking statements speak only as of the date of this Form 12b-25, and the Company undertakes no obligation to update these forward-looking statements to reflect events or circumstances occurring after the date hereof.

(Attach extra Sheets if Needed)

PART IV — OTHER INFORMATION

(1)

Name and telephone number of person to contact in regard to this notification

Ryan C. Wilkins, Esq.

949

725-4115

(Name)

(Area Code)

(Telephone Number)

(2)

Have all other periodic reports required under Section 13 or 15(d) of the Securities Exchange Act of 1934 or Section 30 of the Investment Company Act of 1940 during the preceding 12 months or for such shorter period that the registrant was required to file such report(s) been filed? If answer is no, identify report(s). Yes ☐ No ☒

Annual Reports on Form 10-K for the years ended December 31, 2024 and December 31, 2025, and the Quarterly Reports on Form 10-Q for the quarters ended March 31, 2025, June 30, 2025 and September 30, 2025

(3)

Is it anticipated that any significant change in results of operations from the corresponding period for the last fiscal year will be reflected by the earnings statements to be included in the subject report or portion thereof?  Yes ☒ No ☐

If so, attach an explanation of the anticipated change, both narratively and quantitatively, and, if appropriate, state the reasons why a reasonable estimate of the results cannot be made.

The Company anticipates significant changes in its financial condition and results of operations for the period ended December 31, 2025 relative to the period ended December 31, 2024, primarily as a result of the previously announced (1) termination of the capacity purchase agreement, dated August 19, 2022, previously entered into by and between the Company and American Airlines, Inc., (2) strategic shift in its operations and consideration of other strategic alternatives, and (3) implementation of a workforce reduction plan.

Following the completion of the Aviation Disposition, the Company does not have any material operating assets, is not engaged in any operating business, and does not have any source of revenue from operations. Accordingly, the Company expects significant changes in its financial condition and results of operations for the periods following the completion of the Aviation Disposition relative to its historical financial condition and results of operations. For additional information regarding the Aviation Disposition and the Company’s consideration of strategic alternatives, please refer to Item 8.01 of the Form 8-K.

Harbor Diversified, Inc.

(Name of Registrant as Specified in Charter)

has caused this notification to be signed on its behalf by the undersigned hereunto duly authorized.

Date: April 1, 2026				By:		/s/ Christine R. Deister
				Its:		Chief Executive Officer and Secretary

INSTRUCTION: The form may be signed by an executive officer of the registrant or by any other duly authorized representative. The name and title of the person signing the form shall be typed or printed beneath the signature. If the statement is signed on behalf of the registrant by an authorized representative (other than an executive officer), evidence of the representative’s authority to sign on behalf of the registrant shall be filed with the form.

ATTENTION

Intentional misstatements or omissions of fact constitute Federal Criminal Violations (See 18 U.S.C. 1001).