GT Biopharma Inc美股招股说明书(2026-01-30版)

This prospectus relates to the offering from time to time by the selling stockholders named in this prospectus (the “SellingStockholders”) of up to an aggregate 22,686,349 shares of common stock, par value $0.001 per share (the “Common Stock”), of GTBiopharma, Inc., a Delaware corporation (the “Company”), consisting of (i) 11,257,949 shares of Common Stock issuable upon theconversion of 5,111.1108 shares of Series L 10% Convertible Preferred Stock, par value $0.001 per share (the “Series L PreferredStock” or the “Preferred Shares,” and the shares of Common Stock issuable upon conversion of the Preferred Shares, the “ConversionShares”) issued upon the exercise of certain of the Greenshoe Rights (as defined below) issued in connection with our privateplacement in May 2025, (ii) 11,257,949 shares of Common Stock issuable upon the exercise of vested warrants (the “VestingWarrants,” and the shares of Common Stock issuable upon the exercise of the Vesting Warrants, the “Vesting Warrant Shares”) issuedin connection with our private placement in May 2025, and (iii) 170,451 shares of Common Stock issued to the holders of Series LPreferred Stock of record as of December 18, 2025 as a dividend, which represents 10% of the outstanding stated value of the Series LPreferred Stock, payable on January 1, 2026 (the “Dividend Shares”). The Conversion Shares, the Vesting Warrant Shares and theDividend Shares are collectively referred to as the “Shares.” We are registering the Shares on behalf of the Selling Stockholders, to beoffered and sold by them from time to time. We will not receive any proceeds from the sale of the Shares offered by this prospectus. We have agreed to bear all of the expenses incurred in connection with the registration of the Shares. The SellingStockholders will pay or assume discounts, commissions, fees of underwriters, selling brokers or dealer managers and similarexpenses, if any, incurred for the sale of the Shares of our Common Stock. The Selling Stockholders, or their respective donees, pledgees, transferees or other successors-in-interest, may sell orotherwise dispose of the Shares covered by this prospectus in a number of different ways. We provide more information about how theSelling Stockholders may sell or otherwise dispose of their Shares in the section entitled “Plan of Distribution.” For a list of theSelling Stockholders, see the section entitled “Selling Stockholders.” Our Common Stock is presently listed on the Nasdaq Capital Market (“Nasdaq”) under the trading symbol “GTBP.” OnJanuary 29, 2026, the closing sale price for our Common Stock was $0.68 per share. Investing in our securities involves a high degree of risk. See the section entitled “Risk Factors” beginning on page 6 ofthis prospectus and in the documents incorporated by reference into this prospectus for a discussion of risks that should beconsidered in connection with an investment in our securities. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved ofthese securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminaloffense. The date of this prospectus is January 30, 2026. TABLE OF CONTENTS PageABOUT THIS PROSPECTUS1CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS2PROSPECTUS SUMMARY3THE OFFERING5RISK FACTORS6USE OF PROCEEDS10MARKET INFORMATION FOR SECURITIES AND DIVIDEND POLICY11DESCRIPTION OF CAPITAL STOCK12SELLING STOCKHOLDERS18MATERIAL TAX CONSIDERATIONS21PLAN OF DISTRIBUTION25INCORPORATION OF CERTAIN INFORMATION BY REFERENCE27WHERE YOU CAN FIND MORE INFORMATION28LEGAL MATTERS28EXPERTS28 ABOUT THIS PROSPECTUS This prospectus is part of a registration statement filed with the U.S. Securities and Exchange Commission (the “SEC”) usinga “shelf” registration process. By using a shelf registration statement, the Selling Stockholders may sell up to 22,686,349 shares ofCommon Stock from time to time in one or more offerings as described in this prospectus. We will not receive any proceeds from thesale by the Selling Stockholders of the shares of Common Stock offered pursuant to this prospectus. We may also file a prospectus supplement or post-effective amendment to the registration statement of which this prospectusforms a part that may contain material information relating to these offerings. The prospectus supplement or post-effective amendmentmay also add, update or change information contained in this prospectus with respect to that offering. If there is any inconsistencybetween the information in this prospectus and the applicable prospectus supplement or post-effective amendment, you should rely onthe prospectus supplement or post-effective amendment, as applicable. Before purchasing any securities, you should carefully read thisprospectus, any post-effective amendment, and any applicable prospectus supplement, together with the additional informationdescribed under the heading “Where You C