Firefly Aerospace美国招股说明书（2026年6月1日版）

We are offering 4,000,000 shares and the selling securityholders named in this prospectus (the “Selling Securityholders”) are offering 8,000,000 sharesof Common Stock, par value $0.0001 per share (the “Common Stock”) of Firefly Aerospace Inc. (“Firefly Aerospace”). We intend to use net proceeds received by us from this offering for general corporate and working capital purposes. See “Use of Proceeds.” We will not receive any proceeds from the sale of shares of Common Stock by the Selling Securityholders pursuant to this prospectus. However, we willpay the expenses, other than underwriting discounts and commissions and certain other expenses incurred by the Selling Securityholders in connectionwith the registration of the Common Stock. You should read this prospectus and any prospectus supplement or amendment carefully before you invest in our securities. Our Common Stock is listed on the Nasdaq Global Market under the symbol “FLY.” On May28, 2026, the closing price of our Common Stock was$49.37 per share. Pursuant to the Director Nomination Agreement, AE Industrial Partners, as representative of the Investor Group (as defined below), and as a result of thereceipt of certain voting proxies, controls a majority of the voting power of our outstanding Common Stock with respect to the election of our directors, We are an “emerging growth company” as that term is used in the Jumpstart Our Business Startups Act of 2012 (the“JOBS Act”) and have elected tocomply with certain reduced public company reporting requirements. See “Risk Factors” and “Prospectus Summary—Implications of Being an Investing in our Common Stock involves risks. See “Risk Factors” beginning on page8 of this prospectus and the riskfactors in the documents incorporated by reference in this prospectus to read about factors you should consider beforebuying shares of our Common Stock. Neither the Securities and Exchange Commission (the “SEC”) nor any state securities commission has approved or disapproved of thesesecurities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense. (1)See “Underwriting” for a description of the compensation payable to the underwriters. The Selling Securityholders have granted the underwriters an option for a period of 30 days after this prospectus to purchase up to an additional1,800,000 shares of Common Stock at the public offering price less the underwriting discount. The underwriters expect to deliver the shares of Common Stock to purchasers on June1, 2026. TABLE OF CONTENTS MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES TO NON-U.S. HOLDERS INCORPORATION OF CERTAIN INFORMATION BY REFERENCE WHERE YOU CAN FIND ADDITIONAL INFORMATION We, the Selling Securityholders and the underwriters have not authorized anyone to provide any information or to make any representations other thanthose contained in this prospectus or in any free writing prospectuses we have prepared. We, the Selling Securityholders and the underwriters take noresponsibility for, and can provide no assurance as to the reliability of, any other information that others may provide you. This prospectus is not an offerto sell nor is it seeking an offer to buy these securities in any jurisdiction where the offer or sale is not permitted. We and the Selling Securityholders areoffering to sell, and seeking offers to buy, shares of our Common Stock only under circumstances and in jurisdictions where it is lawful to do so. The For investors outside the United States: neither we, the Selling Securityholders nor any of the underwriters have done anything that would permit thisoffering or the possession or distribution of this prospectus in any jurisdiction where action for those purposes is required, other than in the UnitedStates. Persons outside the United States who come into possession of this prospectus must inform themselves about, and observe any restrictions TRADEMARKS AND TRADE NAMES “Firefly Aerospace,” “Firefly,” “Blue Ghost,” “Elytra,” and other trademarks or service marks of Firefly Aerospace and its direct and indirectsubsidiaries appearing in this prospectus are the property of Firefly Aerospace. This prospectus contains additional trade names, trademarks, and servicemarks of others, which are the property of their respective owners. Solely for convenience, trademarks and trade names referred to in this prospectusgenerally appear without the®or™symbols. Other trademarks, trade names, service marks or copyrights of any other company appearing in this PROSPECTUS SUMMARY The following summary contains selected information contained elsewhere in this prospectus and the documents we incorporate by reference.It does not contain all of the information that is important to you and your investment decision. Before you make an investment decision, you shouldreview this prospectus and the documents incorporated by reference in their entirety, including matters set forth under the hea