Grant Thornton consent added to Firefly (FLY) S-1 post-effective amendment

Rhea-AI Filing Summary

Firefly Aerospace Inc. filed a Post-Effective Amendment No. 1 to its Form S-1 (Registration No. 333-291599) to add as an exhibit the consent of Grant Thornton LLP to use its report dated March 19, 2026.

The amendment references the Company’s Annual Report on Form 10-K for the year ended December 31, 2025 and Prospectus Supplement No. 2 dated March 19, 2026. The registration contemplates sales from time to time after this Registration Statement becomes effective.

As filed with the Securities and Exchange Commission on March 19, 2026.

File No. 333-291599

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

POST-EFFECTIVE AMENDMENT NO. 1 TO

REGISTRATION STATEMENT ON

FORM S-1

UNDER

THE SECURITIES ACT OF 1933

Firefly Aerospace Inc.

(Exact name of Registrant as specified in its charter)

Delaware		3761		81-5194980
(State or other jurisdiction of incorporation or organization)		(Primary Standard Industrial Classification Code Number)		(I.R.S. Employer Identification Number)

1320 Arrow Point Drive #109

Cedar Park, TX 78613

512-893-5570

(Address, including zip code, and telephone number, including area code, of Registrant’s principal executive offices)

Jason Kim

Chief Executive Officer

1320 Arrow Point Drive #109

Cedar Park, TX 78613

512-893-5570

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Robert M. Hayward, P.C.
Kevin M. Frank
Kirkland & Ellis LLP
333 West Wolf Point Plaza
Chicago, IL 60654
(312) 862-2000 David Wheeler
General Counsel
1320 Arrow Point Drive #109
Cedar Park, TX 78613
512-893-5570

Approximate date of commencement of the proposed sale to the public: From time to time after this Registration Statement becomes effective.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act, check the following box. ☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☒

Registration No.: 333-291599

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

Large accelerated filer		☐		Accelerated filer		☐
Non-accelerated filer		☒		Smaller reporting company		☐
				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 7(a)(2)(B) of the Securities Act. ☐

ADDITION OF EXHIBIT

This Post-Effective Amendment No. 1 to the Registration Statement on Form S-1 (File No. 333-291599) is being filed to include as an exhibit Grant Thornton LLP’s consent to the use of its report dated March 19, 2026, with respect to the consolidated financial statements of Firefly Aerospace Inc. and its subsidiaries (the “Company”) included in the Annual Report on Form 10-K of the Company for the year ended December 31, 2025 in such registration statement and the related prospectus. The report of Grant Thornton LLP was filed in the Prospectus Supplement No. 2 dated March 19, 2026 filed pursuant to Rule 424(b)(3).

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PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 16. Exhibits.

Exhibit No.		Description
23.3		Consent of Grant Thornton LLP, independent registered public accounting firm.

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SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in Cedar Park, Texas on March 19, 2026.

FIREFLY AEROSPACE INC.
By:		/s/ Jason Kim
Name:		Jason Kim
Title:		Chief Executive Officer

Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed by the following persons in the capacities and on the dates indicated.

Signature		Title		Date
/s/ Jason Kim Jason Kim		Chief Executive Officer & Director (Principal Executive Officer)		March 19, 2026
/s/ Darren Ma Darren Ma		Chief Financial Officer (Principal Financial Officer)		March 19, 2026
/s/ Remington Wu Remington Wu		Chief Accounting Officer (Principal Accounting Officer)		March 19, 2026
/s/ * Kirk Konert		Director		March 19, 2026
/s/ * Marc Weiser		Director		March 19, 2026
/s/ * Christopher Emerson		Director		March 19, 2026
/s/ * Thomas Zurbuchen		Director		March 19, 2026
/s/ * Pamela Braden		Director		March 19, 2026
/s/ * Kevin McAllister		Director		March 19, 2026
/s/ * Jon Lusczakoski		Director		March 19, 2026
/s/ * Ryan Boland		Director		March 19, 2026

*By: /s/ Darren Ma    Darren Ma, Attorney-in-Fact   

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FAQ

What did Firefly Aerospace (FLY) file in Post‑Effective Amendment No. 1?

Answer: The amendment adds Grant Thornton LLP’s consent to use its auditor’s report dated March 19, 2026 as an exhibit. This consent supports inclusion of the consolidated financial statements in the registration statement and related prospectus.

Does the amendment change the securities offering timing for FLY?

Answer: The filing reiterates that sales may occur from time to time after the Registration Statement becomes effective. The amendment itself does not alter the stated commencement language or provide new timing for specific sales.

Which financial statements does the auditor consent relate to for FLY?

Answer: The consent relates to Grant Thornton LLP’s report on the consolidated financial statements of Firefly Aerospace Inc. and its subsidiaries for the year ended December 31, 2025, included in the Company’s Annual Report on Form 10-K.

What exhibit was added to Firefly’s registration statement (No. 333-291599)?

Answer: Exhibit 23.3 was added: the written consent of Grant Thornton LLP, the Company’s independent registered public accounting firm, permitting use of its March 19, 2026 report in the prospectus.

Does the amendment disclose use of proceeds or new financial terms for FLY?

Answer: The amendment only adds an auditor consent as an exhibit and references Prospectus Supplement No. 2. It does not state any use of proceeds, pricing, or new financial terms within the provided excerpt.