Atai Beckley NV美股招股说明书(2025-12-05版)

123,134,069 Common SharesRegistered for the Securityholders Named Herein Pursuant to the Registration Rights Agreement This prospectus supplement relates to an aggregate 123,134,069 of our common shares, nominal value €0.10 per share(“common shares”) that are already issued and outstanding and are now being registered to satisfy certain registration rightspursuant to that certain registration rights agreement, dated June2, 2025 (the “Registration Rights Agreement”) and the relatedjoinder agreements thereto. These common shares may be offered from time to time by the selling securityholders identified in the The registration of 123,134,069 of our common shares relates to (i) 81,266,384 common shares received by certain of theselling securityholders in connection with the Share Purchase Agreement, dated June2, 2025, among us, Beckley Psytech Limited(“Beckley Psytech”) and certain other parties thereto (as amended by the Side Letter Deed to the Share Purchase Agreement, datedOctober23, 2025, the “SPA”), relating to our acquisition of the entire issued share capital of Beckley Psytech not already owned by The selling securityholders may offer and sell from time to time, together or separately, the common shares described in thisprospectus supplement and the accompanying prospectus through one or more underwriters, dealers and agents, or directly topurchasers, or through a combination of these methods. If any underwriters, dealers or agents are involved in the sale of any of thecommon shares, their names and any applicable purchase price, fee, commission or discount arrangement between or among themwill be set forth, or will be calculable from the information set forth, in the applicable prospectus supplement. See the sections of Our common shares are listed on the Nasdaq Global Market under the symbol “ATAI.” On December4, 2025, the last reportedsale price of our common shares on the Nasdaq Global Market was $4.40 per share. Investing in our securities involves risks. See the “Risk Factors” on page S-6of this prospectus supplement, in thesimilar section contained in the accompanying prospectus and in the documents incorporated by reference in thisprospectus supplement concerning factors you should consider before investing in our securities. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved ofthese securities or passed upon the adequacy or accuracy of this prospectus supplement or the accompanying prospectus.Any representation to the contrary is a criminal offense. TABLE OF CONTENTS TABLE OF CONTENTS ABOUT THIS PROSPECTUS1CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS2TRADEMARKS4WHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCE5THE COMPANY7RISK FACTORS8 TABLE OF CONTENTS ABOUT THIS PROSPECTUS SUPPLEMENT This prospectus supplement is part of a registration statement that we have filed with the Securities andExchange Commission, or SEC, which became automatically effective upon filing, utilizing a “shelf” registrationprocess, and relates to the offering of our common shares. Before buying any of the common shares that the sellingsecurityholders are offering, we urge you to carefully read this prospectus supplement, the accompanying prospectus We and the selling securityholders provide information to you about this offering of our common shares in twoseparate documents that are bound together: (1) this prospectus supplement, which describes the specific detailsregarding this offering and also adds to and updates information contained in the documents incorporated byreferenceinto this prospectus supplement;and(2)the accompanying prospectus,which provides generalinformation, some of which may not apply to this offering. Generally, when we refer to this “prospectus,” we arereferring to both documents combined. If information in this prospectus supplement is inconsistent with theaccompanying prospectus, you should rely on this prospectus supplement. To the extent there is a conflict betweenthe information contained in this prospectus supplement, on the one hand, and the information contained in any You should rely only on the information contained in or incorporated by reference in this prospectussupplement, the accompanying prospectus and any free writing prospectus that we may authorize for use inconnection with this offering. We have not, and the selling securityholders have not, authorized anyone to provideyou with different information. If anyone provides you with different or inconsistent information, you should notrely on it. We are not, and the selling securityholders are not, making an offer to sell these securities in anyjurisdiction where the offer or sale is not permitted or in which the person making that offer or solicitation is notqualified to do so or to anyone to whom it is unlawful to make an offer or solicitation. You should assume that theinformation appearing in this prospectus supplement, the accompanyi