Phio Pharmaceuticals Corp美股招股说明书(2026-04-08版)

We have entered into an At The Market Offering Agreement dated April 8, 2026, or the sales agreement, with H.C.Wainwright & Co., LLC (“Wainwright” or the “Sales Agent”), relating to shares of our common stock, par value $0.0001 per share,offered by this prospectus supplement and the accompanying prospectus. In accordance with the terms of the sales agreement, we mayoffer and sell shares of our common stock having an aggregate offering price of up to $6,360,000 from time to time through or toWainwright, acting as sales agent or principal, pursuant to this prospectus supplement and the accompanying prospectus. Sales of our common stock, if any, under this prospectus supplement and the accompanying prospectus may be made in salesdeemed to be “at the market offerings” as defined in Rule415(a)(4)promulgated under theSecurities Act of 1933, as amended, ortheSecurities Act, including sales made directly on or through the Nasdaq Capital Market or any other existing trading market for theshares of our common stock, sales made to or through a market maker other than on an exchange or otherwise, directly to Wainwrightas principal, in negotiated transactions at market prices prevailing at the time of sale or at prices related to such prevailing marketprices, and/or in any other method permitted by law. Subject to terms of the sales agreement, the Sales Agent is not required to sell anyspecific number or dollar amounts of common stock but will act as our sales agent using commercially reasonable efforts consistentwith its normal trading and sales practices, on mutually agreed terms between the Sales Agent and us. There is no arrangement forfunds to be received in any escrow, trust or similar arrangement. Our common stock is listed on the Nasdaq Capital Market under the symbol “PHIO.” On April 2, 2026, the last reported saleprice of our common stock on The Nasdaq Capital Market was $1.28 per share. We are subject to General Instruction I.B.6 of Form S-3, which limits the amounts that we may sell under the registration statement of which this prospectus supplement is a part. In no eventmay we sell shares pursuant to this prospectus supplement with a value of more than one-third of the aggregate market value of ourcommon stock held by non-affiliates in any 12-month period, so long as the aggregate market value of our common stock held by non-affiliates is less than $75,000,000. The aggregate market value of our outstanding common stock held by non-affiliates pursuant toGeneral Instruction I.B.6 of Form S-3, or the public float, is $19,080,217, which was calculated based on 11,563,768 shares of ouroutstanding common stock held by non-affiliates at a price of $1.65 per share, the closing price of our common stock on February 13,2026, a date that is within 60 days of filing this prospectus supplement. As of the date hereof, we have not sold any shares of ourcommon stock pursuant to General Instruction I.B.6 of Form S-3 during the prior 12 calendar month period that ends on and includesthe date hereof. As a result of these limitations and the current public float of our common stock, and in accordance with the terms ofthe sales agreement, we may offer and sell shares of our common stock having an aggregate offering price of up to $6,360,072.40under the sales agreement. If our public float increases such that we may sell additional shares under the sales agreement and theregistration statement of which this prospectus supplement is a part, we will file another prospectus supplement prior to makingadditional sales. The Sales Agent will be entitled to compensation under the terms of the sales agreement at a commission rate of 3.0% of thegross sales price per share sold. In connection with the sale of shares of our common stock on our behalf, the Sales Agent will bedeemed to be an “underwriter” within the meaning of theSecurities Actand the compensation of the Sales Agent will be deemed to beunderwriting commissions or discounts. We have also agreed to provide indemnification and contributions to the Sales Agent againstcertain liabilities, including liabilities under theSecurities Act. See “Plan of Distribution” beginning on page S-10 for additionalinformation regarding the compensation to be paid to the Sales Agent. This offering pursuant to this prospectus supplement and theaccompanying prospectus will terminate upon the earlier of (a) the sale of shares of our common stock pursuant to this prospectussupplement and the accompanying prospectus having an aggregate sales price of $6,360,000, and (b) the termination of the salesagreement pursuant to its terms. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of thesesecurities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Anyrepresentation to the contrary is a criminal offense. H.C. Wainwright & Co. The date of this prospectus supplement is April 8, 2026 TABLE O