堡垒生物科技股份有限美国存托凭证招股说明书(2025-12-18版)

This prospectus relates to the resale by the selling stockholders (the “Selling Stockholders”) identified in this prospectus under thesection “The Selling Stockholders,” or their pledgees, donees, transferees or other successors in interest, from time to time, of up to600,000 shares (the “Resale Shares”) of our common stock, par value $0.001 per share (“Common Stock”), issuable upon exercise ofthe warrants (the “Warrants”) granted to Oaktree Fund Administration, LLC (“Oaktree”) and certain of its affiliates (the “SellingStockholders”), pursuant to that certain First Amendment to Credit Agreement dated as of December12, 2025 (the “Amendment”) by The Selling Stockholders may resell or dispose of the Resale Shares, or interests therein, at fixed prices, at prevailing market prices atthe time of sale or at prices negotiated with purchasers, to or through underwriters, broker-dealers, agents, or through any other meansdescribed in the section of this prospectus titled “Plan of Distribution”. The Selling Stockholders will each bear their respectivecommissions and discounts, if any, attributable to the sale or disposition of the Resale Shares, or interests therein, held by such Selling Our Common Stock is listed on The Nasdaq Capital Market, or Nasdaq, under the symbol “FBIO.” On December11, 2025 the lastreported sale price of our Common Stock was $2.94 per share. You are urged to obtain current market quotations for our Common Investing in our securities involves risks. You should review carefully the risks and uncertainties described under the heading“Risk Factors” contained in this prospectus and under similar headings in the other documents that are incorporated by Neither the Securities and Exchange Commission (the “SEC”) nor any state securities commission has approved ordisapproved of these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary The date of this Prospectus is December 17, 2025 TABLE OF CONTENTS ABOUT THIS PROSPECTUS This prospectus provides you with a general description of the shares of Common Stock that may be resold by the SellingStockholders. In certain circumstances, we may provide a prospectus supplement that will contain specific information about the termsof a particular offering by the Selling Stockholders. We also may provide a prospectus supplement to add information to, or update orchange information contained in, this prospectus. To the extent there is a conflict between the information contained in this prospectusand any prospectus supplement, you should rely on the information in the prospectus supplement, provided that if any statement in one You should read both this prospectus and any applicable prospectus supplement together with the additional information about ourcompany to which we refer you in the sections of this prospectus titled “Where You Can Find More Information” and “Incorporationof Certain Documents by Reference.” You should rely only on the information contained in or incorporated by reference into thisprospectus and any prospectus supplement. Neither we nor the Selling Stockholders have authorized any dealer, salesperson or otherperson to provide you with different information. You should not assume that the information in this prospectus or any prospectussupplement is accurate as of any date other than the date on the front of those documents or that any document incorporated by Unless the context indicates otherwise, when we refer to “Fortress,” “we,” “our,” “us” and the “Company” in this prospectus, we meanFortress Biotech,Inc., unless otherwise specified. When we refer to “you,” we mean the potential purchasers of the Resale Shares. FORWARD-LOOKING STATEMENTS This prospectus, including the documents that we incorporate by reference, contains predictive or “forward-lookingstatements” within the meaning of the Private Securities Litigation Reform Act of 1995. All statements other than statements of currentor historical fact contained in this prospectus, including statements that express our intentions, plans, objectives, beliefs, expectations,strategies, predictions or any other statements relating to our future activities or other future events or conditions are forward-looking These statements are based on current expectations, estimates and projections made by management about our business, ourindustry and other conditions affecting our financial condition, results of operations or business prospects. These statements are notguarantees of future performance and involve risks, uncertainties and assumptions that are difficult to predict. Therefore, actualoutcomes and results may differ materially from what is expressed or forecasted in, or implied by, the forward-looking statements due our growth strategy;financing and strategic agreements and relationships;our need for substantial additional funds and uncertainties relating to financings;uncertainty related to the timing and amounts expe