Phathom Pharmaceuticals Inc美股招股说明书(2026-01-08版)

6,875,000 Shares of Common StockPre-Funded Warrants to Purchase 1,250,078 Shares of Common Stock We are offering 6,875,000shares of our common stock, $0.0001 par value per share, in this offering. We are also offering, in lieu of shares of commonstock to certain investors that so choose, pre-funded warrants to purchase 1,250,078shares of our common stock. The purchase price of each pre-fundedwarrant equals the price per share at which the shares of our common stock are being sold in this offering, minus $0.001, which is the exercise price ofeach pre-funded warrant per share. Each pre-funded warrant will be exercisable at any time after the date of issuance of such pre-funded warrant, subjectto an ownership limitation. This prospectus supplement also relates to the offering of the shares of our common stock issuable upon the exercise of suchpre-funded warrants. Our common stock is listed on the Nasdaq Global Select Market under the symbol “PHAT.” On January6, 2026, the last reported sale price of ourcommon stock on the Nasdaq Global Select Market was $16.37 per share. There is no established public trading market for the pre-funded warrants, andwe do not expect a market to develop. We do not intend to list the pre-funded warrants on the Nasdaq Global Select Market or any other nationalsecurities exchange or nationally recognized trading system. Investing in our securities involves a high degree of risk. Please read “Risk Factors” beginning on page S-5 of thisprospectus supplement, on page 5 of the accompanying prospectus and the documents incorporated by reference intothis prospectus supplement and the accompanying prospectus. Neither the Securities and Exchange Commission nor any state of securities commission has approved or disapproved of these securities ordetermined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is acriminal offense. Delivery of the shares of common stock and pre-funded warrants to purchasers is expected to be made on or about January9, 2026. We have granted the underwriters an option for a period of 30 days to purchase an additional 1,218,761shares of our common stock. If the underwritersexercise the option in full, the total underwriting discounts and commissions payable by us will be $8,970,085, and total net proceeds to us, beforeexpenses, will be $140,530,089. Joint Book-Running Managers Guggenheim Securities Cantor Co-Managers Table of Contents TABLE OF CONTENTSPageProspectus SupplementABOUT THIS PROSPECTUS SUPPLEMENTS-iiPROSPECTUS SUPPLEMENT SUMMARYS-1RISK FACTORSS-5CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTSS-8USE OF PROCEEDSS-9DILUTIONS-10DESCRIPTION OF PRE-FUNDED WARRANTSS-12MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES OF OUR COMMON STOCK AND PRE-FUNDED WARRANTSS-14UNDERWRITINGS-21LEGAL MATTERSS-30EXPERTSS-30WHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCES-31ProspectusABOUT THIS PROSPECTUS1WHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCE2THE COMPANY4RISK FACTORS5CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS6USE OF PROCEEDS7DIVIDEND POLICY7DESCRIPTION OF CAPITAL STOCK8DESCRIPTION OF DEBT SECURITIES13GLOBAL SECURITIES22PLAN OF DISTRIBUTION26LEGAL MATTERS27EXPERTS27 Table of Contents ABOUT THIS PROSPECTUS SUPPLEMENT This prospectus supplement and the accompanying prospectus dated January7, 2026 are part of a registration statement that we filed with the Securitiesand Exchange Commission, or SEC, as a “well-known seasoned issuer” as defined in Rule 405 under the Securities Act of 1933, as amended, or theSecurities Act, utilizing a “shelf” registration process. This prospectus supplement and the accompanying prospectus relate to the offer by us of shares ofour common stock and pre-funded warrants to certain investors. We provide information to you about this offering of shares of our common stock andpre-funded warrants in two separate documents that are bound together: (1)this prospectus supplement, which describes the specific details regardingthis offering; and (2)the accompanying prospectus, which provides general information, some of which may not apply to this offering. Generally, whenwe refer to this “prospectus,” we are referring to both documents combined. If information in this prospectus supplement is inconsistent with theaccompanying prospectus, you should rely on this prospectus supplement. However, if any statement in one of these documents is inconsistent with astatement in another document having a later date—for example, a document incorporated by reference in this prospectus supplement or theaccompanying prospectus—the statement in the document having the later date modifies or supersedes the earlier statement as our business, financialcondition, results of operations and prospects may have changed since the earlier dates. You should read this prospectus supplement, the accompanyingprospectus, the documents and information incorpo