Outlook Therapeutics Inc. IPO招股说明书（2025年5月14日版本）

21,720,655 shares of Common Stock This Prospectus Supplement No. 1, or the Prospectus Supplement, is being filed to update and supplement the informationcontained in the “Selling Stockholders” section of our prospectus, dated March 28, 2025, which forms a part of our RegistrationStatement on Form S-3 (Registration No. 333-285973), as may be amended and supplemented from time to time, or the Prospectus.The Prospectus, as supplemented by this Prospectus Supplement, relates to the offer and resale from time to time by certain sellingstockholders named in the Prospectus of up to an aggregate of 21,720,655 shares of our common stock, which consists of (i) 7,074,637shares of our common stock issuable upon the exercise of outstanding Tranche B warrants to purchase shares of our common stock, orthe Tranche B Warrants, held by the selling stockholders, all of which were issued by us at the closing of a warrant inducementtransaction on January 17, 2025, or the Warrant Inducement Transaction and (ii) 14,646,018 shares of our common stock issuable This Prospectus Supplement is being filed to amend the selling stockholder information set forth in the Prospectus as set forth onAnnex Aattached hereto. This Prospectus Supplement should be read in conjunction with the Prospectus, and if there is anyinconsistency in the information in the Prospectus and this Prospectus Supplement, you should rely on the information in this Our common stock is listed on The Nasdaq Capital Market under the symbol “OTLK.” On May 13, 2025, the last reported saleprice of our common stock was $2.03 per share. Investing in our common stock involves a high degree of risk. Before making an investment decision, please read theinformation under “Risk Factors” on page 7 of the Prospectus and under similar headings in any amendment or supplement to Neither the SEC nor any state securities commission has approved or disapproved of these securities or determined if theProspectus or the Prospectus Supplement is truthful or complete. Any representation to the contrary is a criminal offense. The date of this Prospectus Supplement is May 14, 2025. ANNEX A AMENDMENT TO SELLING STOCKHOLDER INFORMATION This Prospectus Supplement is being filed in connection with certain changes to the selling stockholder information as set forth inthe Prospectus resulting from the transfer by Altium Healthcare Long Short Onshore Fund LP, or Altium, of 857,142 Tranche BWarrants to funds managed by Empery Asset Management, LP, or Empery. Concurrently with the transfer of the Tranche B Warrants,Altium also transferred 857,142 Tranche A Warrants to funds managed by Empery, which we collectively refer to as the WarrantTransfer. Consequently, the selling stockholder table appearing under the heading “Selling Stockholders” in the Prospectus is hereby The shares of common stock being offered by the selling stockholders are those (i) issuable to the selling stockholders uponexercise of the Tranche B Warrants issued in the Warrant Inducement Transaction and (ii) issuable to one of the selling stockholdersupon conversion of the Note pursuant to the SPA. For additional information regarding the issuance of Tranche B Warrants, Note andSPA, see the sections “Prospectus Summary—Warrant Inducement Transaction” and “Prospectus Summary—The Convertible Note”in the Prospectus. We are registering the resale of shares of common stock issuable upon exercise of the Tranche B Warrants and Beneficial ownership is determined in accordance with the rules of the SEC and includes voting or investment power with respectto our common stock. Generally, a person “beneficially owns” shares of our common stock if the person has or shares with others the The table below lists the selling stockholders and other information regarding the beneficial ownership of the shares of commonstock by each of the selling stockholders. This information has been obtained from the selling stockholders or in Schedules 13G or13D and other public documents filed with the SEC. The second column lists the number of shares of common stock beneficiallyowned by each selling stockholder, as of March 13, 2025, assuming (i) exercise of the Tranche B Warrants held by the sellingstockholders on that date and (ii) the conversion of the Note held by one of the selling stockholders on that date at a conversion priceof $2.26, as applicable, except with respect to the number of shares of common stock beneficially owned by Empery, which reflectsthe Warrant Transfer subsequent to March 13, 2025, each without regard to any limitations on exercises, unless otherwise indicated.The Tranche B Warrants are exercisable only for cash, except in limited circumstances, at any time and expire on March 11, 2030. TheNote is convertible on the earlier of (i) six months following the issuance of the Note and (ii) the date on which the registration In accordance with the terms of the Inducement Letters and SPA, the Prospectus generally covers the resale o