Dianthus Therapeutics Inc美股招股说明书(2026-03-09版)

Common Stock Pre-funded Warrants to Purchase Shares of Common Stock We are offering $400,000,000 of shares of our common stock and, in lieu of common stock to certain investors that so choose, pre-funded warrantsto purchaseshares of our common stock. The purchase price of each pre-funded warrant will equal the price per share at which shares ofour common stock are being sold to the public in this offering, minus $0.001 per share of common stock, the exercise price of each pre-fundedwarrant. The public offering price for each share of common stock is $. We are also offering the shares of our common stock that areissuable from time to time upon exercise of the pre-funded warrants. Our common stock trades on the Nasdaq Capital Market (Nasdaq) under thesymbol “DNTH.” On March6, 2026, the last reported sale price for our common stock on Nasdaq was $65.20 per share. There is no established public trading market for the pre-funded warrants, and we do not expect a market to develop. We do not intend to apply forlisting of the pre-funded warrants on Nasdaq or any securities exchange or nationally recognized trading system. Without an active trading market,the liquidity of the pre-funded warrants will be limited. Investing in our securities involves risks. See the section titled “Risk Factors” beginning on page S-7 of this prospectus supplement andpage 6 of the accompanying prospectus, as well as in the documents incorporated by reference herein and therein, to read about factors youshould consider before buying our securities. Neither the Securities and Exchange Commission nor any other regulatory body have approved or disapproved these securities, or passedupon the accuracy or adequacy of this prospectus supplement or the accompanying prospectus. Any representation to the contrary is acriminal offense. (1)See the section titled “Underwriting” for additional information regarding underwriting compensation. Delivery of the shares of common stock and pre-funded warrants is expected to be made on or about, 2026. The information in this preliminary prospectus supplement is not complete and may be changed. This preliminary prospectussupplement and the accompanying prospectus are not an offer to sell and are not soliciting an offer to buy these securities in anyjurisdiction where the offer or sale is not permitted.We have granted the underwriters an option for a period of 30 days to purchase up to an additional $60,000,000 of shares of our common stock. Ifthe underwriters exercise the option in full, the total underwriting discounts and commissions payable by us will be $and the totalproceeds to us, before expenses, will be $. WilliamBlair Table of Contents TABLE OF CONTENTS PROSPECTUS SUPPLEMENT ABOUT THIS PROSPECTUS SUPPLEMENTPROSPECTUS SUPPLEMENT SUMMARYTHE OFFERINGRISK FACTORSSPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTSUSE OF PROCEEDSDILUTIONDESCRIPTION OF SECURITIES WE ARE OFFERINGU.S. FEDERAL INCOME TAX CONSIDERATIONSUNDERWRITINGLEGAL MATTERSEXPERTSWHERE YOU CAN FIND ADDITIONAL INFORMATIONINCORPORATION OF CERTAIN INFORMATION BY REFERENCE PROSPECTUS ABOUT THIS PROSPECTUSSPECIAL NOTE REGARDING FORWARD LOOKING STATEMENTSTHE COMPANYRISK FACTORSUSE OF PROCEEDSSECURITIES WE MAY OFFERDESCRIPTION OF SECURITIES PLAN OF DISTRIBUTION LEGAL MATTERS Table of Contents ABOUT THIS PROSPECTUS SUPPLEMENT This prospectus supplement is part of a registration statement on Form S-3 that we filed with the Securities and Exchange Commission (“SEC”)pursuant to the Securities Act of 1933, as amended (the “Securities Act”), utilizing a “shelf” registration process. We provide information to you aboutthis offering of our securities in two separate documents that are bound together: (1)this prospectus supplement, which describes the specific detailsregarding this offering; and (2)the accompanying prospectus, which provides general information, some of which may not apply to this offering.Generally, when we refer to this “prospectus,” we are referring to both documents combined. If information in this prospectus supplement is inconsistentwith the accompanying prospectus, you should rely on this prospectus supplement. However, if any statement in one of these documents is inconsistentwith a statement in another document having a later date — for example, a document incorporated by reference in this prospectus supplement — thestatement in the document having the later date modifies or supersedes the earlier statement as our business, financial condition, results of operationsand prospects may have changed since the earlier dates. We have not, and the underwriters have not, authorized anyone to provide you with information other than in this prospectus supplement, theaccompanying prospectus or any free writing prospectus we may authorize to be delivered or made available to you. We take no responsibility for andcannot provide any assurance as to the reliability of any other information others may give you. We are not, and