Aptevo Therapeutics Inc美股招股说明书(2026-09-03版)

This prospectus relates to the resale from time to time by certain selling stockholders named herein (the “SellingStockholders”) of up to 6,444,858 shares of Common Stock, par value $0.001 per share (“Common Stock”), of AptevoTherapeutics Inc. (the “Company,” “us” or “we”), issuable upon exercise of (i) pre-funded common stock purchase warrants topurchase up to 861,708 shares of Common Stock (the “Pre-Funded Warrants,” and the shares of Common Stock issuable uponexercise thereof, the “Pre-Funded Warrant Shares”), (ii) common stock purchase warrants to purchase up to 4,308,540 shares ofCommon Stock (the “Common Warrants,” and the shares of Common Stock issuable upon exercise thereof, the “Common WarrantShares”) and (iii) common stock purchase warrants issued to certain holders of the Company’s existing warrants to purchase up to1,274,610 shares of Common Stock (the “Inducement Warrants,” and the shares of Common Stock issuable upon exercise thereof,the “Inducement Warrant Shares” and together with the Pre-Funded Warrant Shares and the Common Warrant Shares, the “WarrantShares”). The Pre-Funded Warrants, Common Warrants and Inducement Warrants are collectively referred to herein as the“Warrants.” The Pre-Funded Warrants and Common Warrants were issued in a private placement pursuant to the SecuritiesPurchase Agreement, dated August 12, 2026 (the “Purchase Agreement”), and the Inducement Warrants were issued pursuant toWarrant Inducement and Reload Letters, dated August 12, 2026 (the “Inducement Letters”). The Pre-Funded Warrant Shares,Common Warrant Shares and Inducement Warrant Shares are collectively referred to herein as the “Resale Shares.” The Selling Stockholders may resell or dispose of the Resale Shares to or through underwriters, broker-dealers, agents orthrough any other means described in the section of this prospectus entitled “Plan of Distribution.” The Selling Stockholders willbear the costs of commissions and discounts, if any, attributable to the sale or disposition of the Resale Shares. We will bear allcosts, expenses and fees in connection with the registration of the Resale Shares. We will not receive any of the proceeds from thesale of the Resale Shares by the Selling Stockholders. Our Common Stock is listed on the Nasdaq Capital Market under the symbol “APVO.” On September 2, 2026, the lastreported sale price of our Common Stock on the Nasdaq Capital Market was $2.60 per share. Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertaintiesdescribed under the heading “Risk Factors” on page 11 of this prospectus and under similar headings in the applicableprospectus supplement, any free writing prospectuses we have authorized for use in connection with a specific offering andin the documents incorporated by reference herein and therein. Neitherthe Securities and Exchange Commission nor any state securities commission has approved ordisapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contraryis a criminal offense. The date of this prospectus is September 3, 2026. TABLE OF CONTENTS ABOUT THIS PROSPECTUSFORWARD-LOOKING STATEMENTSPROSPECTUS SUMMARYTHE OFFERINGDESCRIPTION OF CAPITAL STOCKRISK FACTORSUSE OF PROCEEDSSELLING STOCKHOLDERSPLAN OF DISTRIBUTIONLEGAL MATTERSEXPERTSWHERE YOU CAN FIND MORE INFORMATION INCORPORATION OF CERTAIN INFORMATION BY REFERENCE ABOUT THIS PROSPECTUS This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission (the "SEC")using a "shelf" registration process pursuant to Rule 415 under the Securities Act of 1933, as amended (the “Securities Act”). Underthis shelf registration process, the Selling Stockholders may, from time to time, sell or otherwise dispose the securities described inthis prospectus in one or more offerings. We will not receive any proceeds from the sale by the Selling Stockholders of thesecurities offered by them described in this prospectus. If information in this prospectus is inconsistent with any document incorporated by reference that was filed with the SECbefore the date of this prospectus, you should rely on this prospectus. This prospectus and the documents incorporated by referenceinclude important information about us, the securities being offered and other information you should know before investing in oursecurities. You should also read and consider information in the documents we have referred you to in the sections of thisprospectus entitled “Where You Can Find Additional Information” and “Incorporation of Certain Information by Reference.” You should rely only on the information contained in, or incorporated by reference into, this prospectus (as supplementedand amended), along with the information contained in any free writing prospectuses. We have not authorized anyone to provideyou with different information. We take no responsibility for and can provide no