BigBear.ai Holdings Inc. American Stock Offering Prospectus (Version as of June 2, 2025)

BigBear.ai Holdings, Inc. Common Stock We have entered into a Controlled Equity OfferingSMSales Agreement (the “Sales Agreement”) with Cantor Fitzgerald& Co. (“Cantor”) relatingto the sale of shares of our common stock, par value $0.0001 per share (“common stock”), offered by this prospectus supplement and the accompanyingprospectus. In accordance with the terms of the Sales Agreement, we may offer and sell shares of common stock having an aggregate offering price of Our common stock is listed on the New York Stock Exchange (“NYSE”) under the symbol “BBAI.” On May30, 2025, the last sale price of ourcommon stock as reported on the NYSE was $4.16 per share. Sales of our common stock, if any, under this prospectus supplement and the accompanying prospectus will be made in sales deemed to be an “atthe market offering” as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended (the “Securities Act”). Cantor is notrequired to sell any specific number or dollar amount of common stock, but will act as our sales agent using commercially reasonable efforts consistent The compensation to Cantor as sales agent will be an amount equal to up to 3.0% of the gross proceeds of any common stock sold under the SalesAgreement. In connection with the sale of the common stock on our behalf, Cantor will be deemed to be an “underwriter” within the meaning of theSecurities Act and the compensation to Cantor will be deemed to be underwriting commissions or discounts. We have also agreed to provide We are an “emerging growth company” under applicable federal securities laws and therefore subject to reduced public companyreporting requirements. An investment in our commonstockinvolves significant risks.These risks are described in the section titled“RiskFactors” beginning on pageS-5of this prospectus supplement and under similar headings in the documents Neither the Securities and Exchange Commission (the “SEC”) nor any state securities commission has approved or disapproved of thesesecurities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the Cantor The date of this prospectus supplement is June2, 2025. TABLE OF CONTENTS ABOUT THIS PROSPECTUS SUPPLEMENTCAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTSPROSPECTUS SUPPLEMENT SUMMARYRISK FACTORSUSE OF PROCEEDSDILUTIONPLAN OF DISTRIBUTIONLEGAL MATTERSEXPERTSWHERE YOU CAN FIND MORE INFORMATIONINCORPORATION OF CERTAIN INFORMATION BY REFERENCE Prospectus ABOUT THIS PROSPECTUS INCORPORATION OF DOCUMENTS BY REFERENCE CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTSSUMMARY OF THE PROSPECTUSRISK FACTORSUSE OF PROCEEDSDESCRIPTION OF CAPITAL STOCK You should rely only on the information contained or incorporated by reference in this prospectus supplement, the accompanyingprospectus or any free writing prospectus that we may provide to you in connection with this offering. We have not, and Cantor has not,authorized anyone to provide you with different information, and you should not rely on any information not contained in or incorporated byreference into this prospectus supplement, the accompanying prospectus or any free writing prospectus that we may provide you. Thisprospectus supplement does not constitute an offer to sell or a solicitation of an offer to buy any securities other than our common stock. We arenot, and Cantor is not, offering to sell shares of our common stock or seeking offers to buy shares of our common stock in any jurisdictions Table of Contents ABOUT THIS PROSPECTUS SUPPLEMENT This document is in two parts. The first part is this prospectus supplement, which contains specific information about the terms on which we areoffering and selling our common stock pursuant to this prospectus supplement and important business information about us and also adds to and updatesinformation contained in the accompanying prospectus and the documents incorporated herein and therein by reference. The second part is theaccompanying prospectus, which provides more general information, some of which may not apply to the offering being made pursuant to this This prospectus supplement and the accompanying prospectus do not contain all of the information included in the Registration Statement, aspermitted by the rules and regulations of the SEC. For further information, we refer you to our Registration Statement,includingits exhibits, of whichthis prospectus supplement and the accompanying prospectus form a part. We are subject to the informational requirements of the Exchange Act, andtherefore file reports and other information with the SEC. Statements contained in this prospectus supplement and the accompanying prospectus about You should read both this prospectus supplement and the accompanying prospectus as well as additional information incorporated by referenceherein and described in the sections titled “Where You Can Find Additional Information” and “Incorpo