iBio Inc美国招股说明书（2026年3月6日版）

PROSPECTUS Up to $100,000,000 Common Stock We have entered into an Open Market Sale AgreementSM(the “Sales Agreement”) with Jefferies LLC (“Jefferies”), dated February27,2026, relating to the sale of shares of our common stock, par value $0.001 per share (the “Common Stock”), offered by this prospectus. Inaccordance with the terms of the Sales Agreement, pursuant to this prospectus, we may offer and sell shares of our Common Stock havingan aggregate offering price of up to $100,000,000 from time to time through or to Jefferies acting as sales agent. Our Common Stock is listed on the Nasdaq Capital Market under the symbol “IBIO.” On March 4, 2026, the last reported sale price of ourCommon Stock on the Nasdaq Capital Market was $2.83 per share. Sales of our Common Stock, if any, under this prospectus will be made in sales deemed to be an “at the market offering” as defined inRule415(a)(4)promulgated under the Securities Act of 1933, as amended (the “Securities Act”). Jefferies is not required to sell any specificnumber or dollar amount of securities, but will act as a sales agent using commercially reasonable efforts consistent with its normal trading The compensation to Jefferies for sales of shares of our Common Stock sold pursuant to the Sale Agreement will be at a commission rate ofup to 3.0% of the aggregate gross proceeds of any shares of our Common Stock sold under the Sales Agreement. In connection with the saleof the Common Stock hereunder on our behalf, Jefferies will be deemed to be an “underwriter” within the meaning of the Securities Act andthe compensation of Jefferies will be deemed to be underwriting commissions or discounts. We have also agreed to provide indemnification We are a “smaller reporting company” as defined under U.S. federal securities laws and as such, we have elected to comply with certainreduced public company reporting requirements for this prospectus and may elect to do so for future filings. See “Prospectus Summary— Investing in our Common Stock involves a high degree of risk. Before making an investment decision, please read the informationunder the heading “Risk Factors” beginning on page 5 of this prospectus and in the documents incorporated by reference into thisprospectus. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of thesesecurities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense. Jefferies The date of this prospectus is March 6, 2026 TABLE OF CONTENTS ABOUT THIS PROSPECTUS This prospectus relates to part of a registration statement on FormS-3 that we have filed with the Securities and Exchange Commission (the“SEC”) under the Securities Act utilizing a “shelf” registration process. Under this shelf registration process, we may sell any combinationof the securities described in our base prospectus included in the shelf registration statement in one or more offerings up to a total aggregate Before buying any of our shares of Common Stock that we are offering, we urge you to carefully read this prospectus, together with theinformation incorporated by reference as described under the headings “Where You Can Find More Information” and “Incorporation of This prospectus describes the terms of this offering of our shares of Common Stock and also adds to and updates information contained inthe documents incorporated by reference into this prospectus. To the extent there is a conflict between the information contained in thisprospectus, on the one hand, and the information contained in any document incorporated by reference into this prospectus that was filedwith the SEC before the date of this prospectus, on the other hand, you should rely on the information in this prospectus. If any statement in You should rely only on the information contained in or incorporated by reference in this prospectus and in any free writing prospectus thatwe have authorized for use in connection with this offering. We have not, and Jefferies has not, authorized anyone to provide you withdifferent information. If anyone provides you with different or inconsistent information, you should not rely on it. We are not, and Jefferiesis not, making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that theinformation appearing in this prospectus, the documents incorporated by reference in this prospectus, and in any free writing prospectus thatwe have authorized for use in connection with this offering, is accurate only as of the date of those respective documents. Our business, We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to the registrationstatement of which this prospectus forms a part or any document that is incorporated by reference in this prospectus were made solely forthe benefit of the parties to such agre