MoonLake Immunotherapeutics-A美股招股说明书(2026-06-22版)

Filed Pursuant to Rule 424(b)(5)Registration No. 333-274286 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 these securities, and are not soliciting an offer to buythese securities, in any jurisdiction where the offer or sale is not permitted. Subject to Completion Preliminary Prospectus Supplement dated June 22, 2026 PRELIMINARY PROSPECTUS SUPPLEMENT(To prospectus dated September 11, 2023) $150,000,000 MOONLAKE IMMUNOTHERAPEUTICS Class A Ordinary SharesPre-funded Warrants to Purchase Class A Ordinary Shares We are offering Class A Ordinary Shares, par value $0.0001 per share, and, in lieu of Class A Ordinary Shares to certain investors thatso choose, pre-funded warrants to purchase up toClass A Ordinary Shares, pursuant to this prospectus supplement and theaccompanying prospectus. The purchase price of each pre-funded warrant will equal the price per share at which our Class A OrdinaryShares are being sold to the public in this offering, minus $0.0001, the exercise price of each pre-funded warrant. The public offeringprice for each Class A Ordinary Share is $. We are also offering the Class A Ordinary Shares that are issuable from time totime upon exercise of the pre-funded warrants. There is no established public trading market for the pre-funded warrants, and we do not expect a market to develop. We do not intendto apply for listing of the pre-funded warrants on the Nasdaq Capital Market or any securities exchange or nationally recognizedtrading system. Without an active trading market, the liquidity of the pre-funded warrants will be limited. Our Class A Ordinary Shares are listed on the Nasdaq Capital Market under the symbol “MLTX.” On June 22, 2026, the last reportedsale price of our Class A Ordinary Shares as reported on the Nasdaq Capital Market was $22.16 per share. Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties describedunder the heading “Risk Factors” on page S-4 of this prospectus supplement, and under similar headings in the documentsthat are incorporated by reference into this prospectus supplement and the accompanying prospectus. Per sharePerPre-fundedwarrantTotalPublic offering price$$$Underwriting discounts and commissions(1)$$$Proceeds to MoonLake Immunotherapeutics, before expenses$$$ (1)See the section of this prospectus supplement entitled “Underwriting” for a description of the compensation payable to theunderwriters. We have granted the underwriters an option to purchase up to $22,500,000 of additional Class A Ordinary Shares, at the publicoffering price, less the underwriting discount, for 30 days after the date of this prospectus supplement. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of thesesecurities or determined if this prospectus supplement and the accompanying prospectus are truthful or complete. Anyrepresentation to the contrary is a criminal offense. Delivery of the Class A Ordinary Shares and pre-funded warrants being offered hereby is expected to be made on or about,2026. TABLE OF CONTENTS Prospectus Supplement ABOUT THIS PROSPECTUS SUPPLEMENTS-iiPROSPECTUS SUPPLEMENT SUMMARYS-1THE OFFERINGS-3RISK FACTORSS-4SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTSS-8USE OF PROCEEDSS-10DILUTIONS-11U.S. FEDERAL INCOME TAX CONSIDERATIONSS-12DESCRIPTION OF SECURITIES WE ARE OFFERINGS-18UNDERWRITINGS-20LEGAL MATTERSS-26EXPERTSS-26WHERE YOU CAN FIND MORE INFORMATIONS-27INCORPORATION OF CERTAIN INFORMATION BY REFERENCES-28 Prospectus ABOUT THIS PROSPECTUSiiCAUTIONARY STATEMENT CONCERNING FORWARD-LOOKING STATEMENTSiiiTHE COMPANY1RISK FACTORS2USE OF PROCEEDS3SECURITIES WE MAY OFFER4DESCRIPTION OF SHARES5DESCRIPTION OF DEBT SECURITIES11DESCRIPTION OF WARRANTS23DESCRIPTION OF UNITS24PLAN OF DISTRIBUTION27LEGAL MATTERS29EXPERTS29WHERE YOU CAN FIND MORE INFORMATION30INCORPORATION OF CERTAIN INFORMATION BY REFERENCE31 We are responsible for the information contained and incorporated by reference in this prospectus supplement, the accompanyingprospectus and in any free writing prospectus that we have authorized for use in connection with this offering. We and the underwritershave not authorized anyone to give you any other information, and we and the underwriters take no responsibility for any otherinformation that others may give you. We and the underwriters are not making offers to sell the securities in any jurisdiction in whichan offer or solicitation is not authorized or permitted or in which the person making such offer or solicitation is not qualified to do soor to anyone to whom it is unlawful to make an offer or solicitation. The information contained and incorporated by reference in thisprospectus supplement, the accompanying prospectus and any free writing prospectus that we and the underwr