Dear Shareholders of atai Life Sciences N.V.:

On behalf of the Board of Directors of atai Life Sciences N.V. (“atai,” “we,” “us”, “our” or “the Company”), we are pleased to enclose the accompanying proxy statement/prospectus relating to our proposed acquisition of Beckley Psytech Limited (“Beckley Psytech”) and our proposed redomiciliation transaction, pursuant to which (i) atai will merge with and into atai Life Sciences Luxembourg S.A. (“atai LuxCo”), with atai LuxCo surviving the merger (the “LuxCo Merger”), and (ii) atai LuxCo will subsequently convert (the “Delaware Conversion”) from a Luxembourg public limited liability company (société anonyme) into a corporation incorporated under the laws of the State of Delaware (such corporation, “atai Delaware” and the transactions described under clauses (i) and (ii) collectively, the “Redomiciliation”). We are requesting that you take certain actions as an atai shareholder.

On June 2, 2025, atai entered into a Share Purchase Agreement (as may be amended from time to time, the “Share Purchase Agreement”), providing that atai will acquire from the shareholders of Beckley Psytech (the “Sellers”) the entire issued share capital of Beckley Psytech not already owned by atai (the “Acquisition”), as described in further detail under “The Share Purchase Agreement—Structure of the Acquisition”. As consideration to be paid to the Sellers and, if applicable, certain optionholders of Beckley Psytech, atai will issue an aggregate of 105,044,902 ordinary shares in the capital of atai with a nominal value of €0.10 per share (“Ordinary Shares”), subject to certain adjustments.

Our Ordinary Shares are listed on the Nasdaq Global Market (“Nasdaq”) under the symbol “ATAI.” As a result, we are subject to Rule 5635(a) of the Nasdaq Stock Market Rules, pursuant to which shareholder approval is required prior to the issuance of securities in connection with certain acquisitions of stock or assets of another company where the issuance equals 20% or more of the ordinary shares or voting power outstanding before such issuance. We expect that the Ordinary Shares to be issued pursuant to the Share Purchase Agreement will represent approximately 49.5% of the outstanding Ordinary Shares prior to giving effect to the Acquisition. This percentage exceeds the applicable 20% threshold and therefore shareholder approval of the issuance of Ordinary Shares (the “Share Issuance”) pursuant to the Share Purchase Agreement is required under the Nasdaq Stock Market Rules.

atai is pursuing the Redomiciliation for a number of reasons. In 2024 and 2025, our board of directors (the “Board”) and management team undertook a review of our existing structure and operations, and particularly the jurisdiction of incorporation of the Company. We believe the Redomiciliation will enhance shareholder value over the long-term by simplifying the corporate structure to gain operational and cost efficiencies. See “The Redomiciliation—Background and Reasons for the Redomiciliation.”

To effect the Redomiciliation, (i) atai and atai LuxCo intend to effect the LuxCo Merger and (ii) atai LuxCo will subsequently effect the Delaware Conversion. As a result of the Redomiciliation, a holder of Ordinary Shares will receive in the LuxCo Merger the same number of atai LuxCo Ordinary Shares that it held in atai prior to the LuxCo Merger (except to the extent such atai shareholder validly exercises its withdrawal rights under Dutch law), and, as a result of the Delaware Conversion, such shareholder will subsequently become the holder of the same number of shares of atai Delaware Common Stock.

In connection with the Acquisition and the Redomiciliation, and subject to the consummation of each of the Redomiciliation and the Acquisition, atai LuxCo expects to change its name to “Atai Beckley Inc.” upon consummation of the Delaware Conversion. If the Acquisition is not consummated, but the Redomiciliation is consummated, atai LuxCo expects to change its name to “Atai Life Sciences Inc.” upon consummation of the Delaware Conversion.

Before the Acquisition and the Redomiciliation can be completed, atai shareholders must vote to approve, among other things, the Acquisition and the other transactions contemplated by the Share Purchase Agreement, including the Share Issuance, and resolve to enter into the LuxCo Merger. atai is sending you this proxy statement/prospectus to ask you to vote in favor of these matters. The Redomiciliation is not contingent on the approval of, or the consummation of, the Acquisition, nor is the consummation of the Acquisition contingent on the approval of, or the consummation of, the Redomiciliation.

Specifically, at the Extraordinary General Meeting, holders of Ordinary Shares will be asked to vote on the following proposals:

Each proposal is more fully described in the accompanying proxy statement/prospectus, which you are encouraged to read carefully.

atai shareholders are entitled to one vote per Ordinary Share held on October 7, 2025 (the “Record Date”) on all matters to be presented at the Extraordinary General Meeting.

The Extraordinary General Meeting will be held at the offices of NautaDutilh N.V., Beethovenstraat 400, 1082 PR Amsterdam, the Netherlands, at 6:00 p.m. (Central European Time) on November 4, 2025. Our Extraordinary General Meeting will be a “hybrid” meeting of shareholders, meaning that you may attend the Extraordinary General Meeting either via the Internet at www.virtualshareholdermeeting.com/ATAI2025SM by following the instructions set forth below or in person. The Board recommends that atai shareholders vote “FOR” each of the Acquisition Proposal, the Share Issuance Proposal, the Director Nominee Proposals, the Governing Documents Proposal, the Redomiciliation Proposal, the Redomiciliation Withdrawal Rights Proposal and the Redomiciliation Share Conversion Proposal.

The adoption of each of the Acquisition Proposal, the Share Issuance Proposal, the Director Nominee Proposals and the Governing Documents Proposal is a condition to completion of the Acquisition and the Acquisition cannot be completed unless such approvals are obtained. In the event atai shareholders do not approve each of these proposals, atai will be required to pay a termination fee as described in further detail under “The Share Purchase Agreement—Termination; Notice of Termination.” The obligations of the parties to complete the Acquisition are subject to the satisfaction or waiver of a number of conditions set forth in the Share Purchase Agreement, a copy of which is attached as Annex A to the accompanying proxy statement/prospectus.

The adoption of each of the Redomiciliation Proposal and the Redomiciliation Withdrawal Rights Proposal is a condition to completion of the Redomiciliation and the Redomiciliation cannot be completed unless such approval is obtained.

The accompanying proxy statement/prospectus describes the Extraordinary General Meeting, the proposals to be considered thereat, the Acquisition (including the Share Issuance), the Share Purchase Agreement, the Redomiciliation and the other transactions, documents and agreements related to the Acquisition (including the Share Issuance) and the Redomiciliation. It also contains or references information about atai and Beckley Psytech and certain related agreements and matters. Please carefully read the entire accompanying proxy statement/prospectus (and the documents incorporated herein by reference), including the section

entitled “Risk Factors” beginning on page 23, for a discussion of the risks relating to the Acquisition, the Combined Group, atai and Beckley Psytech, and the Redomiciliation. You also can obtain information about atai from documents filed with the SEC. Please see the section entitled “Where You Can Find More Information” beginning on page 213 of the accompanying proxy statement/prospectus for how you may obtain such information.

Neither the SEC nor any state securities commission has approved or disapproved of the securities to be issued in connection with the Acquisition or the Redomiciliation described in the accompanying proxy statement/prospectus or determined if the accompanying proxy statement/prospectus is accurate or complete. Any representation to the contrary is a criminal offense.

Our Ordinary Shares are listed on Nasdaq under the symbol “ATAI”. We will seek, and expect to receive, approval from Nasdaq to list the atai Delaware Common Stock under the same symbol after the Redomiciliation.

The accompanying proxy statement/prospectus is dated September 24, 2025 and is first being mailed to atai shareholders of record on or about such date.

The Extraordinary General Meeting of Shareholders (the “Extraordinary General Meeting”) of atai Life Sciences N.V., a public limited liability company (naamloze vennootschap) incorporated under the laws of the Netherlands (the “Company” or “atai”), will be held at the offices of NautaDutilh N.V., Beethovenstraat 400, 1082 PR Amsterdam, the Netherlands, at 6:00 p.m. (Central European Time) on November 4, 2025. Our Extraordinary General Meeting will be a “hybrid” meeting of shareholders, meaning that you may attend the Extraordinary General Meeting either via the Internet at www.virtualshareholdermeeting.com/ATAI2025SM by following the instructions set forth below or in person. We believe this virtual attendance alternative enables increased shareholder participation from locations around the world. We recommend that you log in a few minutes before the Extraordinary General Meeting to ensure you are logged in when the Extraordinary General Meeting starts.

Shareholders may attend the Extraordinary General Meeting either virtually, by visiting www.virtualshareholdermeeting.com/ATAI2025SM and entering your 16-digit control number, or in person.

The agenda for the Extraordinary General Meeting is as follows:

No business shall be voted on at the Extraordinary General Meeting, except such items as included in the above mentioned agenda. These items of business are described in the enclosed proxy statement/prospectus.

The Board has unanimously approved the Share Purchase Agreement, the Acquisition and the issuance of Ordinary Shares pursuant to the Share Purchase Agreement, and the Redomiciliation. The Board unanimously recommends that atai shareholders vote “FOR” the Acquisition Proposal, the Share Issuance Proposal, the Director Nominee Proposals, the Governing Documents Proposal, the Redomiciliation Proposal, the Redomiciliation Withdrawal Rights Proposal and the Redomiciliation Share Conversion Proposal.

The record date for the Extraordinary General Meeting in respect of our Ordinary Shares is October 7, 2025 (the “Record Date”). Those who are holders of our Ordinary Shares, or who otherwise have voting rights and/or meeting rights with respect to our Ordinary Shares, on the Record Date, provided that they are recorded as such in our shareholders’ register or in the register maintained by our U.S. transfer agent, may attend and, if relevant, vote at the Extraordinary General Meeting (the “Persons with Meeting Rights”).

Persons with Meeting Rights who wish to attend the Extraordinary General Meeting, virtually or in person, or be represented by proxy, must notify us of their identity and intention to attend the Extraordinary General Meeting by e-mail (addressed to shareholdermeeting@atai.com) or in writing (addressed to atai Life Sciences N.V., Corporate Secretary, Prof. J.H. Bavincklaan 7, 1183 AT Amstelveen, the Netherlands). This notice must be received by us no later than 5:00 p.m. (Central European Time) on October 31, 2025. Persons with Meeting Rights who have not complied with this requirement may be refused attendance at the Extraordinary General Meeting. Persons with Meeting Rights may be represented at the Extraordinary General Meeting through the use of a written or electronically recorded proxy. Holders who hold Ordinary Shares in “street name” who wish to attend the Extraordinary General Meeting should present a copy of their “legal proxy” or “instrument of proxy” obtained from your broker, bank, or other holder of record upon entry to the Extraordinary General Meeting, failing which such holder concerned may be refused entry to the Extraordinary General Meeting. We have also provided information regarding how shareholders can engage during the Extraordinary General Meeting, including how they can vote, ask questions, request technical support and access information following the Extraordinary General Meeting within the enclosed proxy statement/prospectus.

If you have questions concerning the Acquisition Proposal, the Share Issuance Proposal, the Director Nominee Proposals, the Governing Documents Proposal, the Redomiciliation Proposal, the Redomiciliation Withdrawal Rights Proposal, the Redomiciliation Share Conversion Proposal, the Extraordinary General Meeting or the proxy statement/prospectus, would like additional copies or need help voting your Ordinary Shares, please contact Innisfree M&A Incorporated, atai’s proxy solicitor, by calling 877-750-0926 (U.S. and Canada toll-free), 412-232-3651 (international) or 212-750-5833 (banks and brokers).

The accompanying proxy statement/prospectus provides you with more specific information concerning the Acquisition Proposal, the Share Issuance Proposal, the Director Nominee Proposals, the Governing Documents Proposal, the Redomiciliation Proposal, the Redomiciliation Withdrawal Rights Proposal and the terms of the Share Purchase Agreement, the Acquisition and the Redomiciliation. We encourage you to carefully read the accompanying proxy statement/prospectus and accompanying annexes.

It is important that your shares be represented, regardless of the number of shares you may hold and whether you plan to attend in person. The Acquisition cannot be completed unless atai’s shareholders adopt the Acquisition Proposal, the Share Issuance Proposal, the Director Nominee Proposals, and the Governing Documents Proposal, and the Redomiciliation cannot be completed unless atai’s shareholders adopt the Redomiciliation Proposal and the Redomiciliation Withdrawal Rights Proposal. We urge you to vote your

shares or to submit your proxy. Proxies may be submitted up until 5:59 a.m. Central European Time on November 4, 2025 (the “Cut-off Time”) via a toll-free telephone number (call +1-800-690-6903) or over the Internet (visit www.proxyvote.com), as described in further detail in the enclosed materials, or by signing, dating and mailing the proxy card in the enclosed return envelope. Voting your shares or submitting your proxy, as applicable, will be important for the presence of a quorum at the Extraordinary General Meeting and will save us the expense of further solicitation. Submitting a proxy will not prevent you from voting your shares at the Extraordinary General Meeting if you desire to do so, as your proxy is revocable at your option.

If you own Ordinary Shares at the close of business on October 7, 2025, you are entitled to one vote per share upon each matter presented at our Extraordinary General Meeting to be held on November 4, 2025. In order for shareholders whose shares are held in an account at a brokerage firm, bank or other nominee (i.e., in “street name”) as of October 7, 2025 to vote their shares at the Extraordinary General Meeting, they will need to obtain a legal proxy from the broker, bank or other nominee that holds their shares authorizing them to vote at the Extraordinary General Meeting.

If you hold shares in “street name,” unless you provide specific instructions by completing and returning the voting instruction form or following the instructions provided to you to vote your shares via telephone or the Internet, your broker may not vote on the matters to be considered at the Extraordinary General Meeting. For your vote to be recognized, you will need to communicate your voting decisions to your broker, bank or other nominee at least one business day prior to the date of the Extraordinary General Meeting.

Your vote is important. The Board strongly encourages you to exercise your right to vote. Voting early helps ensure that we receive a quorum of shares necessary to hold the Extraordinary General Meeting.

If you have any questions about the proxy voting process, please contact Innisfree M&A Incorporated, atai’s proxy solicitor, by calling 877-750-0926 (U.S. and Canada toll-free), 412-232-3651 (international) or 212-750-5833 (banks and brokers).

This proxy statement/prospectus incorporates by reference important business and financial information about atai from other documents that are not included in or delivered with this proxy statement/prospectus. For a listing of the documents incorporated by reference into this proxy statement/prospectus, see the section entitled “Where You Can Find More Information” beginning on page 213.

You may request copies of this proxy statement/prospectus and any of the documents incorporated by reference herein, exclusive of exhibits, without charge, upon written or oral request to atai’s principal executive offices. A reasonable fee will be charged for copies of exhibits. The address of our principal executive office is listed below.

If you would like to request any of the atai documents that are incorporated by reference into this proxy statement/prospectus, please do so by October 28, 2025 in order to receive them before the Extraordinary General Meeting.

You may also obtain any of the documents incorporated by reference into this proxy statement/prospectus without charge through the SEC’s website at www.sec.gov. You also may access this proxy statement/prospectus and our Annual Report on Form 10-K for the year ended December 31, 2024 and Quarterly Reports on Form 10-Q for any subsequent interim period at www.proxyvote.com. In addition, you may access our Annual Report on Form 10-K for the year ended December 31, 2024 and Quarterly Reports on Form 10-Q for any subsequent interim period at www.atai.com.

We are not incorporating the contents of the websites of the SEC, atai or any other entity into this proxy statement/prospectus. We are providing the information about how you can obtain certain documents that are incorporated by reference into this proxy statement/prospectus at these websites only for your convenience.

In this proxy statement/prospectus, unless otherwise specified or the context otherwise requires: “$,” “USD” and “U.S. dollar” each refer to the United States dollar and “£,” and “GBP” each refer to the British pound sterling.

atai’s financial statements incorporated by reference or included, as applicable, in this proxy statement/prospectus have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) for financial information and pursuant to the rules and regulations of the SEC.

Beckley Psytech’s financial statements included in this proxy statement/prospectus have been prepared in accordance with International Financial Reporting Standards as issued by the International Accounting Standards Board (the “IFRS”).

This proxy statement/prospectus include certain references to financial measures that were not prepared in accordance with GAAP or IFRS. atai believes that the presentation of non-GAAP or non-IFRS results, as applicable, is useful to investors for analyzing atai and Beckley Psytech’s respective business and business trends and comparing performance to prior periods, along with enhancing investors’ ability to view the atai or Beckley Psytech results, as applicable, from management’s perspective. The presentation of this additional information should not be considered a substitute for results prepared in accordance with GAAP or IFRS. The presentation of this non-GAAP or non-IFRS information is not meant to be considered in isolation or as a substitute for atai’s or Beckley Psytech’s consolidated financial results prepared in accordance with GAAP or IFRS, respectively.

Solely for convenience, some of the trademarks, service marks, logos and trade names referred to in this proxy statement/prospectus are presented without the ^® and ™ symbols, but such references are not intended to indicate, in any way, that atai or Beckley Psytech, as applicable, will not assert, to the fullest extent under applicable law, atai’s or Beckley Psytech’s rights or the rights of the applicable licensors to these trademarks, service marks and trade names.

“Apeiron” means Apeiron Investment Group Ltd.

“Apeiron Voting Agreement” means the voting agreement entered into by and among Beckley Psytech, atai and Apeiron concurrently with the execution of the Share Purchase Agreement, a copy of which is attached as Annex D-2 to this proxy statement/prospectus.

“Articles of Association” means atai’s articles of association, as amended, dated as of June 25, 2025.

“atai” means atai Life Sciences N.V., a public company with limited liability (naamloze vennootschap) incorporated under Dutch law.

“atai Delaware” means Atai Beckley Inc. or Atai Life Sciences Inc., as applicable, a Delaware corporation.

“atai Delaware Common Stock” means the shares of common stock of atai Delaware.

“atai Delaware Proposed Organizational Documents” means the Proposed Charter and Proposed Bylaws.

“atai LuxCo” means atai Life Sciences Luxembourg S.A., a Luxembourg public limited liability company (société anonyme).

“atai LuxCo Board” means the board of directors of atai LuxCo.

“atai LuxCo Ordinary Share” means an ordinary share in the capital of atai LuxCo.

“Acquisition” means the acquisition by atai from the Sellers of the entire issued share capital of Beckley Psytech not already owned by atai pursuant to and in accordance with the terms of the Share Purchase Agreement.

“Acquisition Proposal” means the approval, subject to the adoption of each of (A) the Share Issuance Proposal, (B) the Governing Documents Proposal and (C) the Director Nominee Proposals (each as defined below), also within the meaning of Section 2:107a of the DCC, of the consummation of the Acquisition by atai in accordance with the terms of the Share Purchase Agreement.

“Beckley Carve-Out Steps Plan” means the steps plan for the Beckley Carve-Out in agreed form pursuant to the Share Purchase Agreement, or such amended version as may be agreed by the Seller Representative and atai from time to time.

“Beckley Carve-Out” means the reorganization involving the carve-out of Eleusis from the Pre-Carve-Out Beckley Group, as described in the Beckley Carve-Out Steps Plan.

“Beckley Group” means Beckley Psytech and its subsidiaries (excluding Eleusis and its subsidiaries).

“Beckley Founders” means Cosmo Feilding-Mellen and Michael Norris.

“Beckley Optionholders” means the holders of Beckley Options.

“Beckley Options” means the options over ordinary shares in Beckley Psytech.

“Beckley Psytech” means Beckley Psytech Limited.

“Beckley Shares” means the entire issued share capital of Beckley Psytech other than the shares held by atai.

“Board” means the board of directors of atai.

“Business Day” means any day other than a Saturday, Sunday or public holiday in the City of London, England; Berlin, Germany; Amsterdam, The Netherlands; or New York, United States of America.

“Buyer Share Price” means the higher of (i) the VWAP for the period commencing January 1, 2025 to the date falling ten Business Days prior to the date of atai’s general meeting where Shareholder Approval is adopted (the “Reference Date”); or (ii) the VWAP for the 30-day period prior to the Reference Date.

“Cash Compensation” has the meaning as set out in “The Redomiciliation—Withdrawal Mechanism.”

“Closing” means the closing of the Acquisition.

“CMS” means CMS Cameron McKenna Nabarro Olswang LLP, counsel to Beckley Psytech.

“Combined Group” means atai (prior to the LuxCo Merger) or atai LuxCo (following the LuxCo Merger) or atai Delaware (following the Delaware Conversion), as applicable, and its subsidiaries, including the Beckley Group following Closing.

“Consideration Shares” means 105,044,902 newly issued, unregistered Ordinary Shares to be issued to the Sellers and, if applicable, certain optionholders of Beckley Psytech, subject to certain adjustments, pursuant to and in accordance with the Share Purchase Agreement.

“Deed of Amendment I” means the deed of amendment to the Articles of Association in the form attached to this proxy statement/prospectus as Annex G-1 (English translation attached as Annex G-2).

“Deed of Amendment II” means the deed of amendment to the Articles of Association in the form attached to this proxy statement/prospectus as Annex H-1 (English translation attached as Annex H-2).

“Deed of Amendment III” means the deed of amendment to the Articles of Association in the form attached to this proxy statement/prospectus as Annex I-1 (English translation attached as Annex I-2).

“DCC” means the Dutch Civil Code (Burgerlijk Wetboek), as amended from time to time.

“Delaware Conversion” has the meaning as set out in “The Redomiciliation—Steps of the Redomiciliation”.

“Delaware Conversion Effective Time” has the meaning as set out in “The Redomiciliation—Steps of the Redomiciliation”.

“Director Nominee Proposals” means the appointment, subject to the adoption of each of (A) the Acquisition Proposal, (B) the Governing Documents Proposal and (C) the Share Issuance Proposal, of each of Mr. Cosmo Feilding-Mellen and Dr. Robert Hershberg as non-executive directors of atai.

“Eleusis” means Eleusis Holdings Limited, a wholly-owned subsidiary of Beckley Psytech.

“Exchange Act” means the Securities Exchange Act of 1934, as amended.

“Extraordinary General Meeting” means the extraordinary meeting of atai shareholders to be held at the offices of NautaDutilh N.V., Beethovenstraat 400, 1082 PR Amsterdam, the Netherlands, at 6:00 p.m. (Central European Time) on November 4, 2025 to which this proxy statement/prospectus relates.

“Fairness Opinion” means the opinion letter delivered by Guggenheim Securities, dated June 2, 2025, a copy of which is attached as Annex B of this proxy statement/prospectus.

“Formula” has the meaning as set out in “The Redomiciliation—Withdrawal Mechanism”.

“GAAP” means United States generally accepted accounting principles.

“Governing Documents Proposal” means the amendment, subject to the adoption of each of (A) the Acquisition Proposal, (B) the Director Nominee Proposals and (C) the Share Issuance Proposal, of the Articles of Association to change atai’s name pursuant to and as contemplated by the Deed of Amendment I.

“Guggenheim Securities” means Guggenheim Securities, LLC.

“HMRC” means HM Revenue & Customs.

“Innisfree” means Innisfree M&A Incorporated.

“June PIPE Financing” means the purchase, pursuant to certain subscription agreements dated as of June 2, 2025, by the June PIPE Investors of 9,993,341 Ordinary Shares for a purchase price of $1.84 per share and a pre-funded warrant to purchase 6,311,006 Ordinary Shares with an exercise price of $0.01, for a purchase price of $1.84 per Ordinary Share underlying the pre-funded warrant less the exercise price for the pre-funded warrant of $0.01 per share.

“June PIPE Investors” means Adage Capital Partners LP and Ferring Ventures S.A.

“July PIPE Financing” means the purchase, pursuant to certain subscription agreements dated as of July 1, 2025, by the July PIPE Investors of 18,264,840 Ordinary Shares for a purchase price of $2.19 per share and a pre-funded warrant to purchase 4,566,210 Ordinary Shares with an exercise price of $0.01, for a purchase price of $2.19 per Ordinary Share underlying the pre-funded warrant less the exercise price for the pre-funded warrant of $0.01 per share.

“July PIPE Investors” means Ferring Ventures S.A., Apeiron and certain other investors.

“Latham & Watkins” means Latham & Watkins LLP, counsel to atai.

“Lock-Up Agreement” means the Lock-Up Agreement, dated June 2, 2025, by and between atai and Apeiron, a copy of which is attached as Annex E to this proxy statement/prospectus.

“Lock-up Period” means the period that commences from the date of execution of the Share Purchase Agreement and terminates on the date that is the later of (i) sixty days following the public announcement of the results of Beckley Psytech’s Phase 2b Clinical Trial (as defined in the Share Purchase Agreement) in respect of BPL-003, (ii) the Closing or (iii) the date on which the Share Purchase Agreement is terminated.

“Longstop Date” means 5:30 p.m. (British Summer Time) on December 2, 2025 or such later time and date as may be agreed in writing between the Seller Representative and atai; provided, that if the Shareholder Approval has not been satisfied as of the Longstop Date, but all other conditions set forth have been satisfied or waived (except for those conditions that by their nature are to be satisfied at the Closing), then the Longstop Date shall be automatically extended by 90 days on up to two occasions.

“LuxCo Extraordinary General Meeting” means the extraordinary general meeting of shareholders of atai LuxCo, to take place in front of a Luxembourg notary, at which atai, as sole shareholder of atai LuxCo, will vote to approve the LuxCo Merger and the Delaware Conversion.

“LuxCo Merger” means the merger of atai with and into atai LuxCo, with atai LuxCo surviving the merger.

“Luxembourg Articles of Association” means atai LuxCo’s articles of association dated as of August 6, 2025.

“Luxembourg Companies Act” means the Luxembourg act on commercial companies dated August 10, 1915, as amended from time to time.

“Mayer Brown” means Mayer Brown LLP, U.S. counsel to Beckley Psytech.

“Merger Effective Time” has the meaning as set out in “The Redomiciliation—Steps of the Redomiciliation.”

“Merger Plan” means the merger plan prepared by the Board and the board of directors of atai LuxCo, dated September 18, 2025, a copy of which is attached as Annex K to this proxy statement/prospectus.

“Milestone Condition” means the achievement of statistical significance on the primary endpoint (MADRS) change at week four of the Phase 2B clinical trial in respect of BPL-003 with a p<0.05, with (i) fewer than or equal to 3 individual cases of drug-related serious adverse events observed in the 8 mg arm, and (ii) less than a total of 6% drug-related serious adverse events observed in the 12mg arm respectively during the Phase 2B clinical trial. “serious adverse events” shall have the same meaning as given in the Phase 2B clinical trial protocol, and the drug relatedness assessment shall be determined by the primary investigator of the Phase 2B clinical trial in its sole discretion.

“Nasdaq” means the Nasdaq Global Market LLC.

“Nasdaq Rules” means the rules and regulations of Nasdaq.

“Ordinary Shares” means the ordinary shares in the capital of atai with a nominal value of €0.10 per share.

“PIPE Financings” means the June PIPE Financing and the July PIPE Financing.

“PIPE Investors” means the June PIPE Investors and the July PIPE Investors.

“Pre-Carve-Out Beckley Group” means Beckley Psytech and its subsidiaries prior to the Beckley Carve-Out (including Eleusis and its subsidiaries).

“Proposed Bylaws” means the bylaws of atai Delaware as they will read upon completion of the Redomiciliation, the form of which is included as Annex J-2 to this proxy statement/prospectus.

“Proposed Charter” means the certificate of incorporation of atai Delaware as it will read upon completion of the Redomiciliation, the form of which is included as Annex J-1 to this proxy statement/prospectus.

“Record Date” means October 7, 2025.

“Redomiciliation” means, collectively, (i) the LuxCo Merger and (ii) the subsequent Delaware Conversion.

“Redomiciliation Proposal” means the entering into of the LuxCo Merger in accordance with the Merger Plan.

“Redomiciliation Withdrawal Rights Proposal” means the amendment to the Articles of Association to include a formula on the basis of which cash compensation to atai shareholders who validly exercise their withdrawal right in connection with the LuxCo Merger, pursuant to and as contemplated by the Deed of Amendment II.

“Redomiciliation Share Conversion Proposal” means the amendment to the Articles of Association to convert Ordinary Shares into a separate class of B shares if and to the extent atai shareholders exercise their withdrawal right under Dutch law in connection with the LuxCo Merger, pursuant to and as contemplated by the Deed of Amendment III.

“Registration Rights Agreement” means the Registration Rights Agreement, dated June 2, 2025, by and between atai, Apeiron, Christian Angermayer, Ferring Ventures S.A., Adage Capital Partners LP and certain other parties thereto or who may subsequently become party thereto, a copy of which is attached as Annex C to this proxy statement/prospectus.

“Replacement Awards” has the meaning as set out in “The Share Purchase Agreement—Treatment of Outstanding Beckley Options in the Acquisition.”

“Restricted Business” has the meaning set out in “The Share Purchase Agreement—Restrictive Covenants.”

“S&C” means Sullivan & Cromwell LLP, counsel to Apeiron.

“SEC” means the U.S. Securities and Exchange Commission.

“Securities Act” means the Securities Act of 1933, as amended.

“Seller Representative” means Michael Norris.

“Sellers” means the shareholders of Beckley Psytech, excluding atai.

“Selling Shareholders” has the meaning set out in “The Share Purchase Agreement—Seller Drag-Along.”

“Series C Shares” has the meaning set out in “The Acquisition—Background of the Acquisition.”

“Series C Investment” has the meaning set out in “The Acquisition—Background of the Acquisition.”

“Shareholder Approval” means the adoption by atai shareholders of each of the Acquisition Proposal, the Share Issuance Proposal, the Director Nominee Proposals, and the Governing Documents Proposal.

“Shareholders Rights Agreement” means the Shareholders Rights Agreement, dated June 2, 2025, by and between atai and Apeiron, a copy of which is attached as Annex F to this proxy statement/prospectus.

“Share Purchase Agreement” means the Share Purchase Agreement, dated June 2, 2025, by and among atai, certain selling shareholders of Beckley Psytech and Beckley Psytech, a copy of which is attached as Annex A to this proxy statement/prospectus.

“Share Issuance” means an issuance of the Consideration Shares pursuant to the Share Purchase Agreement.

“Share Issuance Proposal” means the approval, subject to the adoption of each of (A) the Acquisition Proposal, (B) the Governing Documents Proposal and (C) the Director Nominee Proposals, for the purposes of complying with the applicable provisions of Nasdaq Listing Rule 5635(a), of the Share Issuance.

“Voting Agreements” means the Apeiron Voting Agreement and the voting agreements entered into by atai, its directors and the members of its executive team and Beckley Psytech, concurrently with the execution of the Share Purchase Agreement, the form of which is attached as Annex D-1 to this proxy statement/prospectus.

“VWAP” means the volume-weighted average price per share of the Ordinary Shares.

“Withdrawal Period” has the meaning as set out in “The Redomiciliation—Withdrawal Mechanism”.

“Withdrawal Request” has the meaning as set out in “The Redomiciliation — Withdrawal Mechanism”.

“Withdrawal Request Form” has the meaning as set out in “The Redomiciliation—Withdrawal Mechanism”.

“Withdrawing Shareholders” has the meaning as set out in “The Redomiciliation—Withdrawal Mechanism”.

“Warranty Condition” means, as at Closing: (a) the warranty given by the Beckley Founders to atai that those Sellers that executed the Share Purchase Agreement on June 2, 2025 are either an “accredited investor” as defined in Rule 501(a) of Regulation D of the Securities Act or not a U.S person as such term is defined under Regulation S of the Securities Act, and that each such Seller has delivered a certification of such “accredited investor” status to atai, being true and accurate as if repeated immediately prior to Closing; and (b) each business warranty given by the Beckley Founders to atai and each warranty given by the Sellers to atai being true and accurate as if repeated immediately prior to Closing, except where the inaccuracies (i) would not impede the Closing, or (ii) would not (save for matters related to the BPL-003 Phase 2B clinical trial that have arisen between the top line read out of the results of such clinical trial and Closing, other than matters relating to the clinical validity of such trial), individually or in aggregate, have a material adverse effect on the Beckley Group (such material adverse effect having a value in excess of £25,000,000).

This proxy statement/prospectus contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. We intend such forward-looking statements to be covered by the safe harbor provisions for forward-looking statements contained in Section 27A of the Securities Act, and Section 21E of the Exchange Act. All statements contained in this proxy statement/prospectus, other than statements of historical fact, should be considered forward-looking statements, including without limitation statements regarding expectations regarding the Closing, including timing and approvals; expectations regarding operations of the Combined Group, including strategic value of the clinical development programs for patients and shareholders as well as expectations regarding financial synergies; timing and results of Beckley Psytech’s BPL-003 Phase 2b trial and related data readouts (results of such Phase 2b trial have now been made available, as previously reported by atai); expectations regarding Beckley’s other clinical assets, including ELE-101; our business strategy and plans; and the potential, success, cost and timing of development of our product candidates, and the product candidates of those companies we invest in; potential future changes to jurisdiction of tax residency or jurisdiction of incorporation and the effects of those changes on us and the effect of the approval of certain proposals contained in this proxy statement/prospectus on the structure and composition of our Board. The words “believe,” “may,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “expect,” “could,” “would,” “project,” “plan,” “potentially,” “preliminary,” “likely,” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these words.

We have based these forward-looking statements largely on our current expectations and projections about future events and trends that we believe may affect our financial condition, results of operations, business strategy, short-term and long-term business operations and objectives, and financial needs. These forward-looking statements are neither promises nor guarantees, and are subject to a number of important factors that could cause actual results to differ materially from any future results, performance or achievements express or implied by the forward-looking statements, including without limitation: (i) the proposed Acquisition may not be completed in a timely manner or at all, including the risk that any required shareholder approvals are not obtained; (ii) the failure to realize the anticipated benefits of the proposed transaction; (iii) the possibility that any or all of the various conditions to the consummation of the Acquisition may not be satisfied or waived; (iv) the occurrence of any event, change or other circumstance that could give rise to the termination of the Share Purchase Agreement; (v) the effect of the announcement or pendency of the business combination on our ability to retain and hire key personnel, or our operating results and business generally; (vi) the effects of the Redomiciliation on trading, liquidity and the price of atai securities; and (vii) other important factors described in the section titled “Risk Factors” in our most recent Annual Report on Form 10-K filed with the SEC, as such factors may be updated from time to time in our other filings with the SEC.

Any forward-looking statements made herein speak only as of the date of this proxy statement/prospectus, and you should not rely on forward-looking statements as predictions of future events. Although we believe that the expectations reflected in the forward-looking statements are reasonable, we cannot guarantee that the future results, performance or achievements reflected in the forward-looking statements will be achieved or will occur. Except as required by applicable law, we undertake no obligation to update any of these forward-looking statements for any reason after the date of this proxy statement/prospectus or to conform these statements to actual results or revised expectations. Additionally, certain information we may disclose (either herein or elsewhere) is informed by the expectations of various stakeholders or third-party frameworks and, as such, may not necessarily be material for purposes of our filings under U.S. federal securities laws, even if we use “material” or similar language in discussing such matters.

You should read and consider risk factors specific to atai’s business that will also affect the Combined Group after the Acquisition. These risks are described in the sections entitled “Risk Factors” in atai’s Annual Report on Form 10-K for the fiscal year ended December 31, 2024 and in other documents incorporated by reference into this proxy statement/prospectus. Please see the section entitled “Where You Can Find More Information” beginning on page 213 of this proxy statement/prospectus for the location of information incorporated by reference into this proxy statement/prospectus.

The market price of Ordinary Shares has fluctuated since the date of the announcement of the parties’ entry into the Share Purchase Agreement and will continue to fluctuate from the date of this proxy statement/prospectus to the date of the Extraordinary General Meeting, the date the Acquisition is completed and thereafter. However, the number of Ordinary Shares to be issued by atai pursuant to the Share Purchase Agreement will not be changed to reflect changes in the trading price of the Ordinary Shares between now and the time the Acquisition is completed. Therefore, even if the trading price of Ordinary Shares increases, existing atai shareholders will not benefit from less dilution because this change in trading price will not impact the number of shares issuable pursuant to the Share Purchase Agreement.

The issuance of Ordinary Shares pursuant to the Share Purchase Agreement could have the effect of depressing the market price of Ordinary Shares, through dilution of earnings per share or otherwise. Any dilution of, or delay of any accretion to, atai’s earnings per share could cause the price of Ordinary Shares to decline or increase at a reduced rate.

Based on the number of Ordinary Shares issued and outstanding as of June 30, 2025, the number of Ordinary Shares issuable as the Share Consideration would represent approximately 28.2% of our outstanding Ordinary Shares, after giving effect to the Acquisition and certain other transactions described therein, including the consummation of the July PIPE Financing, and assuming conversion of all warrants, convertible securities and equity awards using the treasury stock method.

The respective obligations of atai, the Sellers, the Beckley Optionholders and Beckley Psytech to complete the Acquisition are subject to the satisfaction at or prior to the Closing of numerous conditions, including obtaining the Shareholder Approval.

Certain of the conditions to completion of the Acquisition are not within atai’s control, and atai cannot predict when, or if, these conditions will be satisfied. If any of these conditions are not satisfied or waived prior to the Longstop Date, it is possible that the Share Purchase Agreement may be terminated. Although atai, the Sellers, the Beckley Optionholders and Beckley Psytech have agreed in the Share Purchase Agreement to use all reasonable endeavors and fully cooperate in all actions and omissions to ensure the shareholder approval condition is satisfied as soon as practicable, these and other conditions to the Closing may fail to be satisfied. In addition, satisfying the conditions to and completion of the Acquisition may take longer, and could cost more, than atai expects. atai cannot predict whether and when these other conditions will be satisfied. Furthermore, the requirements for obtaining the required approvals could delay the Closing for a significant period of time or prevent it from occurring. Any delay in completing the Acquisition may adversely affect the benefits that atai expects to achieve if the Acquisition and the integration of atai’s and Beckley Psytech’s respective businesses are not completed within the expected timeframe. There can be no assurance that all required approvals will be obtained or obtained prior to the Longstop Date.

If the Acquisition is not completed for any reason, atai would be subject to a number of risks, including the following:

If the Acquisition is not completed, the risks described above may materialize and cause atai’s share price to be negatively impacted.

The completion of the Acquisition may trigger a change in control or other provisions in certain agreements to which Beckley Psytech is a party. If atai and Beckley Psytech are unable to negotiate waivers of those provisions, the counterparties may exercise their rights and remedies under the agreements, potentially terminating the agreements, or seeking monetary damages. Even if atai and Beckley Psytech are able to negotiate waivers, the counterparties may require a fee for such waivers or seek to renegotiate the agreements on terms less favorable to the Combined Group.

atai and Beckley Psytech have incurred and are expected to continue to incur a number of non-recurring costs associated with negotiating and completing the Acquisition, combining the operations of the companies and achieving desired synergies. These costs have been, and will continue to be, substantial and, in many cases, will be borne by atai whether or not the Acquisition is completed. A substantial majority of non-recurring expenses will consist of transaction costs and include, among others, fees paid to advisors, employee retention, severance and benefit costs, financing costs, and other transaction expenses. atai will also incur costs related to formulating and implementing integration plans, including facilities and systems consolidation costs and other employment-related costs. atai will continue to assess the magnitude of these costs and additional unanticipated costs may be incurred in connection with the Acquisition and the integration of the two companies’ businesses. While atai has assumed that a certain level of expenses would be incurred, there are many factors beyond atai’s control that could affect the total amount or the timing of the expenses. The costs described above and any unanticipated costs and expenses, many of which will be borne by atai even if the Acquisition is not completed, could have an adverse effect on atai’s financial condition and operating results.

The Combined Group may never become profitable, even if the Combined Group is able to complete clinical development for one or more product candidates and eventually commercialize such product candidates. The Combined Group will need to successfully complete significant research, development, testing and regulatory compliance activities that, together with projected general and administrative expenses, is expected to result in substantial increased operating losses for at least the next several years. Even if the Combined Group does achieve profitability, it may not be able to sustain or increase profitability on a quarterly or annual basis.

Beckley Psytech is an early-stage company with no revenues to date and it has incurred net losses in each year since its inception and has a limited operating history, which makes it difficult to evaluate its current business and prospects. These historical losses and uncertainties in the Beckley Psytech business could continue to affect the Combined Group following the Closing.

The Combined Group will require substantial additional funds to conduct the costly and time-consuming clinical efficacy trials necessary to pursue regulatory approval of each potential product candidate and to continue the development of future product candidates. The Combined Group’s future capital requirements will depend upon a number of factors, including: the number and timing of future product candidates in the pipeline; progress with and results from preclinical testing and clinical trials; the ability to manufacture sufficient drug supplies to complete preclinical and clinical trials; success in preparing, filing, acquiring, prosecuting, maintaining and enforcing patent and other intellectual property claims; progress with and results from obtaining regulatory approvals and favorable reimbursement or formulary acceptance; and the success in scaling up its commercial operations and organizational infrastructure.

Raising additional capital may be costly or difficult to obtain and could significantly dilute shareholders’ ownership interests or inhibit the Combined Group’s ability to achieve its business objectives. If the Combined Group raises additional funds through public or private equity offerings, the terms of these securities may include liquidation or other preferences that adversely affect the rights of its shareholders. Further, to the extent that the Combined Group raises additional capital through the sale of Ordinary Shares or securities convertible or exchangeable into Ordinary Shares, its shareholders’ ownership interest in the Combined Group will be diluted. In addition, any debt financing may subject the Combined Group to fixed payment obligations and covenants limiting or restricting its ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. If the Combined Group raises additional capital through marketing and distribution arrangements or other collaborations, strategic alliances or licensing arrangements with third parties, the Combined Group may have to relinquish certain valuable intellectual property or other rights to its product candidates, technologies, future revenue streams or research programs or grant licenses on terms that may not be favorable to it. Even if the Combined Group were to obtain sufficient funding, there can be no assurance that it will be available on terms acceptable to the Combined Group or its shareholders.

The success of the Acquisition will depend on, among other things, the Combined Group’s ability to combine each of atai’s and Beckley Psytech’s businesses in a manner that realizes anticipated synergies and benefits and meets or exceeds the forecasted stand-alone cost savings anticipated by the Combined Group. Over time, atai anticipates that the Combined Group will benefit from significant synergies, based on, among other things, increased scale. If the Combined Group is not able to successfully achieve these synergies, or the cost to achieve these synergies is greater than expected, then the anticipated benefits of the Acquisition may not be realized fully or at all or may take longer to realize than expected.

The success of the Acquisition will also depend on the ability of the product candidates to achieve anticipated clinical, regulatory and commercial outcomes. Clinical trials are inherently uncertain, and preliminary or early-stage results may not be predictive of final outcomes or lead to regulatory approval. Furthermore, even if regulatory approval is obtained, the Combined Group may face significant commercialization challenges or encounter competition sooner than expected. If Beckley Psytech’s product candidates do not demonstrate safety or efficacy in later-stage trials, fail to receive regulatory approvals, encounter intellectual property challenges or face unforeseen commercial or competitive obstacles, the Combined Group may not realize the expected benefits of the Acquisition.

atai and Beckley Psytech have operated and, until the Closing, will continue to operate independently. Upon completion of the Acquisition, their respective businesses may not be integrated successfully. It is possible that the integration process could result in the loss of suppliers, vendors, landlords, joint venture partners or other business partners, the disruption of either company’s or both companies’ ongoing businesses, inconsistencies in standards,

controls, procedures and policies, potential unknown liabilities and unforeseen expenses or delays associated with and following completion of the Acquisition or higher than expected integration costs and an overall post-completion integration process that takes longer than originally anticipated. The following considerations, among others, may need to be addressed in integrating the operations of atai and Beckley Psytech in order to realize the anticipated benefits of the Acquisition:

In addition, at times the attention of certain members of either company’s or both companies’ management and resources may be focused on completion of the Acquisition and the integration of the businesses of the two companies and diverted from day-to-day business operations or other opportunities that may have been beneficial to each such company, which may disrupt each company’s ongoing business and ultimately the business of the Combined Group following the Closing.

This proxy statement/prospectus includes unaudited pro forma condensed combined financial information for the Combined Group, which gives effect to the Acquisition, the July PIPE Financing, the Beckley Carve-Out, the Redomiciliation, the Promissory Note, and certain other related transactions and should be read in conjunction with the financial statements and accompanying notes of atai and Beckley Psytech which are incorporated by reference or included in this proxy statement/prospectus. The unaudited pro forma condensed combined financial information contained in this proxy statement/prospectus is being presented for illustrative purposes only and should not be considered to be indicative of the Combined Group’s results of operations or financial condition following the Closing. The unaudited pro forma condensed combined financial information has been derived from the historical financial statements of atai and Beckley Psytech and adjustments, assumptions and preliminary estimates have been made in connection with the preparation of this information. The information upon which these adjustments and assumptions have been made is preliminary, and these kinds of adjustments, assumptions and estimates are difficult to make with accuracy.

Moreover, the unaudited pro forma condensed combined financial information does not reflect all costs that are expected to be incurred by the Combined Group in connection with the Acquisition. For example, the impact of any incremental costs incurred in coordinating the operations of atai and Beckley Psytech are not reflected in the unaudited pro forma condensed combined financial information. In addition, the unaudited pro forma condensed combined financial information does not include, among other things, estimated cost synergies, adjustments related to restructuring or integration activities, future acquisitions, dispositions and other expenses not yet known or probable, or impacts of change in control provisions that are currently not factually supportable or probable of occurring.

As a result, the actual results of operations and financial condition of the Combined Group following the Closing may not be consistent with, or evident from, the unaudited pro forma condensed combined financial information. The assumptions used in preparing the unaudited pro forma condensed combined financial information may not prove to be accurate, and other factors may affect the Combined Group’s results of operations or financial condition following the Closing. Given Beckley Psytech’s limited operating history, current net losses, and inherent business

uncertainties, there is an increased risk that the Combined Group’s future financial performance may deviate significantly from the pro forma estimates. Any potential decline in the Combined Group’s financial condition or results of operations may cause significant variations in the price of Ordinary Shares following the Closing.

The unaudited pro forma condensed combined financial information in this proxy statement/prospectus is based on the best information available, which in part includes a number of estimates and assumptions. These estimates and assumptions may prove not to be accurate, and accordingly, the pro forma financial information included herein does not necessarily reflect the financial condition or results of operations that the Combined Group would have achieved during the periods presented or those that it will achieve in the future, and such information should not be relied upon as an indicator of future performance, financial condition or liquidity.

This proxy statement/prospectus includes certain financial forecasts considered by atai in connection with the Acquisition. None of the financial forecasts prepared by atai were prepared with a view towards public disclosure or compliance with the published guidelines of the SEC, GAAP or the guidelines established by the American Institute of Certified Public Accountants for preparation and presentation of financial forecasts. These forecasts are inherently based on various estimates and assumptions that are subject to the judgment of those preparing them. These forecasts are also subject to significant economic, competitive, industry and other uncertainties and contingencies, all of which are difficult or impossible to predict and many of which are beyond the control of atai. Important factors that may affect the actual results of atai and Beckley Psytech and cause the internal financial forecasts to not be achieved include risks and uncertainties relating to atai’s and Beckley Psytech’s businesses, industry performance, the regulatory environment, general business and economic conditions and other factors described under the section entitled “Cautionary Note Regarding Forward-Looking Statements” in this proxy statement/prospectus.

In addition, the financial forecasts also reflect assumptions that are subject to change and do not reflect revised prospects for atai’s and Beckley Psytech’s businesses, changes in general business or economic conditions or any other transaction or event that has occurred or that may occur and that was not anticipated at the time the financial forecasts were prepared. In addition, since such financial forecasts cover multiple years, the information by its nature becomes less predictive with each successive year. There can be no assurance that atai’s, Beckley Psytech’s or the Combined Group’s financial condition or results of operations will be consistent with those set forth in such forecasts.

The market price of the Combined Group’s ordinary shares following the Acquisition could be subject to significant fluctuations. Market prices for securities of early-stage pharmaceutical, biotechnology, and other life sciences companies have historically been particularly volatile. Some of the factors that may cause the market price of the Combined Group’s ordinary shares to fluctuate following the Acquisition include:

Moreover, the stock markets in general have experienced substantial volatility that has often been unrelated to the operating performance of individual companies or the biotechnology sector. These broad market fluctuations may also adversely affect the trading price of the Combined Group’s ordinary shares.

In the past, following periods of volatility in the market price of a company’s securities, shareholders have often instituted class action securities litigation against those companies. Regardless of the merits or the ultimate results of such litigation, if instituted, such litigation could result in substantial costs and diversion of management’s attention and resources, which could significantly harm the Combined Group’s profitability and reputation.

Additionally, a decrease in the share price of the Combined Group may cause the Combined Group’s ordinary shares to no longer satisfy the continued listing standards of Nasdaq. If the Combined Group is not able to maintain the requirements for listing on Nasdaq, it could be delisted, which could have a materially adverse effect on its ability to raise additional funds as well as the price and liquidity of its Ordinary Shares.

The Combined Group is expected to continue to be an “emerging growth company,” as defined in the Jumpstart Our Business Startups Act of 2012 (“JOBS Act”), and therefore will be able to take advantage of certain exemptions from various reporting requirements that are applicable to other companies that are not “emerging growth companies” including not being required to comply with the auditor attestation requirements of Section 404(b) of the Sarbanes-Oxley Act of 2002 (the “Sarbanes-Oxley Act”).

The Combined Group must maintain effective internal control over financial reporting in order to accurately and timely report its results of operations and financial condition. In addition, as a public company, the Sarbanes-Oxley Act requires, among other things, that the Combined Group assess the effectiveness of its disclosure controls and procedures quarterly and the effectiveness of the Combined Group’s internal control over financial reporting at the end of each fiscal year. Beckley Psytech, being a privately held company, has not previously been subject to the requirements of the Sarbanes-Oxley Act or similar public company regulatory standards, which may result in additional challenges in integrating and aligning internal controls and compliance processes following the Acquisition.

The rules governing the standards that must be met for the Combined Group management to assess the Combined Group’s internal control over financial reporting pursuant to Section 404 of the Sarbanes-Oxley Act are complex and require significant documentation, testing and possible remediation. These stringent standards require that the Combined Group’s audit committee be advised and regularly updated on management’s review of internal control over financial reporting. The Combined Group’s management may not be able to effectively and timely implement controls and procedures that adequately respond to the increased regulatory compliance and reporting requirements that are applicable to the Combined Group as a public company. If the Combined Group fails to staff the Combined Group’s accounting, finance and information technology functions adequately or maintain internal control over financial reporting adequate to meet the demands that will be placed upon the Combined Group as a public company, including the requirements of the Sarbanes-Oxley Act, the Combined Group’s business and reputation may be harmed and its share price may decline. Furthermore, investor perceptions of the Combined Group may be adversely affected, which could cause a decline in the market price of its ordinary shares.

The current expectation is the Combined Group will retain its future earnings, if any, to fund the development and growth of the Combined Group’s business. As a result, capital appreciation, if any, of the Combined Group’s ordinary shares will be shareholders’ sole source of gain, if any, for the foreseeable future.

The Combined Group’s ability to compete in the highly competitive pharmaceuticals industry depends on its ability to attract and retain highly qualified managerial, scientific, medical, legal, sales and marketing and other personnel. The Combined Group will be highly dependent on its management and scientific personnel. Following the Acquisition, there is a risk that key personnel of Beckley Psytech may leave the Combined Group, which could disrupt operations and negatively impact integration efforts. The loss of the services of any of these individuals could impede, delay or prevent the successful development of the Combined Group’s product pipeline, completion of its planned clinical trials, commercialization of its product candidates or in-licensing or acquisition of new assets and could negatively impact its ability to implement successfully its business plan. If the Combined Group loses the services of any of these individuals, it might not be able to find suitable replacements on a timely basis or at all, and its business could be harmed as a result. The Combined Group might not be able to attract or retain qualified management and other key personnel in the future due to the intense competition for qualified personnel among biotechnology, pharmaceutical and other businesses.

On June 2, 2025, atai entered into the Registration Rights Agreement providing for certain registration rights with respect to Ordinary Shares held by such holders from time to time. It is expected that Beckley Psytech shareholders and, if applicable, certain Beckley Optionholders that receive Share Consideration will enter into joinders to become parties to the Registration Rights Agreement at the Closing.

The Registration Rights Agreement requires atai to file a registration statement under the Securities Act providing for the resale of all or part of the registrable securities held by the parties thereto as promptly as practicable, and in any event within 30 calendar days following the earlier of (i) the closing of the transactions contemplated by the Share Purchase Agreement and (ii) the termination of the Share Purchase Agreement, and use reasonable best efforts to cause such registration statement to be declared effective within the timelines specified therein, and thereafter to keep such registration statement effective for the periods specified therein. Apeiron will have customary demand rights that will require atai to file registration statements registering its registrable securities.

It is possible that some or all of the Beckley Psytech shareholders and optionholders, if applicable, will decide to sell some or all of the Share Consideration after the expiration of applicable lock-up obligations. Any disposition of shares by a significant shareholder, or the perception in the market that such dispositions could occur, may cause the price of Ordinary Shares to fall. Any such decline could impair atai’s ability to raise capital through future sales of Ordinary Shares.

There can be no assurance that any or all of the anticipated benefits of the Redomiciliation will be achieved. Achieving the anticipated benefits of the Redomiciliation is subject to a number of risks and uncertainties, including factors that we do not and cannot control. In addition, if the expected benefits of the Redomiciliation do not meet expectations of investors or securities analysts, the price of the atai Delaware Common Stock following completion of the Redomiciliation may decline. For a description of the potential strategic opportunities and other benefits the Board believes are afforded by the Redomiciliation, see “The Redomiciliation—Background and Reasons for the Redomiciliation.”

Completion of the Redomiciliation is conditional, among other things, upon the adoption of the Redomiciliation Proposal and the Redomiciliation Withdrawal Rights Proposal by atai shareholders at the Extraordinary General Meeting. Although atai is diligently applying its efforts to take, or cause to be taken, all actions to do, or cause to be done, all things necessary, proper or advisable to obtain the requisite approvals, there can be no assurance that these conditions will be fulfilled or that the Redomiciliation will be completed. In addition, a creditor opposition period will have to be observed in connection with the LuxCo Merger that may cause delays in the implementation of the LuxCo Merger.

Furthermore, the Board has reserved the right to delay or abandon the Redomiciliation at any time prior to the LuxCo Merger if it determines for any reason that the consummation of the Redomiciliation, or any part thereof, would be inadvisable or not in the best interests of our shareholders.

Under Dutch law, any atai shareholder who voted against the Redomiciliation Proposal at the Extraordinary General Meeting and who does not wish to receive shares in the capital of atai LuxCo pursuant to the LuxCo Merger may exercise a withdrawal right by filing a request with atai for cash compensation within one month after the date of the Extraordinary General Meeting. Depending on the aggregate amount of cash compensation that atai would have to pay pursuant to the valid exercise of these withdrawal rights, this may have a significant impact on our cash position and may cause our Board to determine that the consummation of the Redomiciliation, or any part thereof, is inadvisable and to abandon the Redomiciliation.

atai and its management have allocated and will continue to be required to allocate time and resources to effect the completion of the Redomiciliation and related and incidental activities. There is a risk that the challenges associated with managing these various initiatives as described in this proxy statement/prospectus may have a business impact and that consequently the underlying businesses will not perform in line with expectations. This could have an adverse effect on the business, financial condition and reputation of our Company before and after the Redomiciliation.

In addition, atai expects to incur a number of significant non-recurring costs associated with the Redomiciliation, including legal fees, accountants’ fees, proxy solicitor fees, filing fees, mailing expenses and financial printing expenses. There can be no assurance that the actual costs will not exceed those estimated and the actual completion of the Redomiciliation may result in additional and unforeseen expenses. The substantial majority of these costs will be incurred regardless of whether the Redomiciliation is completed and prior to your vote to adopt the Redomiciliation Proposal, the Redomiciliation Withdrawal Rights Proposal and the Redomiciliation Share Conversion Proposal at the Extraordinary General Meeting. While it is expected that benefits of the Redomiciliation

achieved by atai Delaware will offset these transaction costs over time, this net benefit may not be achieved in the short-term or at all, particularly if the domestication is delayed or does not happen at all. The Board may decide to defer or abandon the Redomiciliation at any time prior to the LuxCo Merger. In addition, even if each of the Redomiciliation Proposal and the Redomiciliation Withdrawal Rights Proposal is adopted by the shareholders of atai, we will not effect the Redomiciliation if any of the conditions to the Redomiciliation fails to be satisfied (unless waived by the Board).

As discussed more fully under “U.S. Federal Income Tax Considerations,” it is intended that each of the LuxCo Merger and the Delaware Conversion qualify as an F reorganization for U.S. federal income tax purposes. However, atai has not sought, and does not intend to seek, any ruling from the IRS with respect to the qualification of each of the LuxCo Merger and the Delaware Conversion as an F Reorganization. No assurance can be given that the IRS will agree with the views expressed herein, or that a court will not sustain any challenge by the IRS in the event of litigation. If the LuxCo Merger or the Delaware Conversion fails to qualify as an F Reorganization, a U.S. Holder (as defined in “U.S. Federal Income Tax Considerations—U.S. Holders”) of Ordinary Shares or the atai LuxCo Ordinary Shares, as applicable, generally would recognize gain or loss with respect to its Ordinary Shares or atai LuxCo Ordinary Shares, as applicable, in an amount equal to the difference, if any, between the fair market value of the corresponding atai LuxCo Ordinary Shares or shares of atai Delaware Common Stock, as applicable, received in the LuxCo Merger and the Delaware Conversion, as applicable, and the U.S. Holder’s adjusted tax basis in its Ordinary Shares or atai LuxCo Ordinary Shares, as applicable, surrendered.

Assuming that each of the LuxCo Merger and the Delaware Conversion qualifies as an F Reorganization, subject to the PFIC rules discussed under “U.S. Federal Income Tax Considerations—U.S. Holders—Tax Effects of the Redomiciliation to U.S. Holders—PFIC Considerations”, U.S. Holders generally will be subject to Section 367(b) of the Code. A U.S. Holder whose Ordinary Shares, on the date of the Redomiciliation, have a fair market value of less than $50,000 and who, on the date of the Redomiciliation, beneficially owns (actually or constructively) less than 10% of the total combined voting power of all classes of atai stock entitled to vote and less than 10% of the total value of all classes of atai stock generally will not recognize any gain or loss and will not be required to include any part of atai’s earnings and profits in income as a result of the Redomiciliation. A U.S. Holder whose Ordinary Shares, on the date of the Redomiciliation, have a fair market value of $50,000 or more and, who on the date of the Redomiciliation, beneficially owns (actually or constructively) less than 10% of the total combined voting power of all classes of atai stock entitled to vote and less than 10% of the total value of all classes of atai stock, generally will recognize gain (but not loss) in respect of the Redomiciliation as if such U.S. Holder exchanged its Ordinary Shares for shares of atai Delaware Common Stock in a taxable transaction, unless such U.S. Holder elects in accordance with applicable Treasury Regulations to include in income as a deemed dividend deemed paid by atai the “all earnings and profits amount” (as defined in the Treasury Regulations under Section 367 of the Code) attributable to the Ordinary Shares held directly by such U.S. Holder. A U.S. Holder who, on the day of the Redomiciliation, beneficially owns (actually or constructively) 10% or more of the total combined voting power of all classes of atai stock entitled to vote or 10% or more of the total value of all classes of atai stock, generally will be required to include in income as a deemed dividend deemed paid by atai LuxCo the “all earnings and profits amount” (as defined in the Treasury Regulations under Section 367 of the Code) attributable to the existing shares held directly by such U.S. Holder as a result of the Redomiciliation. atai does not expect to have a material amount of earnings and profits on the date of the Redomiciliation. However, it is possible that, notwithstanding atai’s expectations, the amount of atai’s cumulative net earnings and profits could be positive through the date of the Redomiciliation. Therefore, there can be no assurance that atai will not have a material amount of earnings and profits on the date of the Redomiciliation.

Additionally, following the Redomiciliation, dividends paid to a Non-U.S. Holder (as defined in “U.S. Federal Income Tax Considerations—Non-U.S. Holders”) in respect of its shares of atai Delaware Common Stock may be subject to U.S. federal withholding taxes.

The tax consequences of the Redomiciliation are complex and will depend on a holder’s particular circumstances. All holders are urged to consult their tax advisor regarding the tax consequences to them of the Redomiciliation, including the applicability and effect of U.S. federal, state, local and non-U.S. tax laws. For a more complete discussion tax considerations of the Redomiciliation, see “Netherlands Tax Considerations” and “U.S. Federal Income Tax Considerations”.

With respect to the Luxembourg direct tax consequences of the holders, such consequences will also depend on a holder’s particular circumstances. However, no Luxembourg adverse tax consequences should arise provided that

the holders: i) do not hold a participation representing more than 10% of atai LuxCo’s share capital, and ii) holders have not been Luxembourg tax resident for more than fifteen years while becoming non-resident less than five year before atai LuxCo’s re-domiciliation.

As further described under “Netherlands Tax Considerations—Material Dutch Tax Consequences of the LuxCo Merger”, atai’s shareholders who are not residents of the Netherlands should generally not be subject to Dutch income tax in connection with the Redomiciliation, subject to certain exceptions. atai’s shareholders who are residents of the Netherlands may be subject to Dutch income tax in connection with the Redomiciliation, depending on the specific tax regime applicable to such holders.

Shareholders should generally not be subject to Dutch dividend withholding tax as a result of the LuxCo Merger, except where a shareholder exercises its withdrawal right and receives Cash Compensation. If a shareholder receives Cash Compensation, Dutch dividend withholding tax should be withheld at a rate of 15% by atai from the Cash Compensation amount that such shareholder is entitled to receive if, and to the extent that, such amount exceeds the average paid-up capital recognized as paid-up capital on the Ordinary Shares for Dutch dividend withholding tax purposes.

For a more detailed discussion of the Dutch tax considerations relating to the Redomiciliation for atai’s shareholders, please refer to the section entitled “Netherlands Tax Considerations—Material Dutch Tax Consequences of the LuxCo Merger.”

Following the Redomiciliation, the Proposed Charter and the Proposed Bylaws will be the constitutive documents of atai Delaware. These new constitutive documents and Delaware law will contain provisions that differ from those included in the Articles of Association and the laws of the Netherlands and, therefore, certain rights as a shareholder of atai Delaware may differ materially from the rights currently possessed as a shareholder of atai. For example, under Dutch law, shareholders have pre-emptive rights with respect to the issuance of shares of the same class (subject to certain statutory exceptions and unless such pre-emptive rights have been excluded or limited), which is not the case under Delaware law, unless such pre-emptive rights are granted pursuant to the Proposed Bylaws. Also, under Dutch law, the general meeting decides on the issuance of shares (unless the Board has been authorized by the general meeting to do so), whereas, under Delaware law, subject to the Nasdaq Rules, the Board may decide on share issuances without shareholder approval, subject to there being sufficient unissued authorized share capital. Furthermore, the Dutch Corporate Governance Code will no longer apply to atai. See “Comparison of Shareholders Rights between Netherlands Law and Delaware Law” for a description of the material differences between the governance of atai under the Articles of Association and the laws of the Netherlands, compared to the governance of atai Delaware under the Proposed Charter and Proposed Bylaws and the Delaware law. Such differences and other changes in the applicable law and atai’s constitutive documents may adversely affect the rights of atai’s shareholders.

Completion of the Redomiciliation is contingent on factors and circumstances of which some are not, or not completely, within the control of atai. As a result, the Redomiciliation may not be implemented or may not be implemented according to the timeline as currently foreseen by atai, including as a result of the following factors and circumstances:

Certain aspects of the tax treatment of the Redomiciliation and atai Delaware going forward depend on determinations of facts and interpretations of applicable tax laws for which no clear precedent or authority is available. Relevant tax laws, and case law, policies and practices on their application and interpretation are continuously under review and are subject to change, which may result in new or revised interpretation or application of relevant statutory provisions, statutory changes, revisions to regulations, policies and decrees, including the Dutch tax Decree on the conversion of legal entities (Besluit omzetting rechtspersonen) dated March 30, 2022, and other modifications. The expected tax treatment of the Redomiciliation and atai Delaware going forward may be modified by administrative, legislative or judicial interpretation or changes at any time, and any such action may apply on a retroactive or retrospective basis. This could lead to additional taxes to be paid by atai Delaware and consequently, atai Delaware may have to engage in tax litigation to defend or achieve results reflected in prior estimates, declarations or assessments which may be time-consuming and expensive.

For a discussion of the Dutch tax and U.S. federal income tax considerations of the Redomiciliation, see “U.S. Federal Income Tax Considerations” and “Netherlands Tax Considerations”.

As a result of the Redomiciliation, atai will be domiciled in the State of Delaware. Certain shareholders of atai may pursuant to their investment policies not be able to, or otherwise wish not to, hold or invest in shares of a Delaware issuer. In addition, some shareholders may sell their Ordinary Shares upon the completion of the Redomiciliation, all of which may, as a result, have an adverse effect on trading, liquidity and the price of the Ordinary Shares and/or shares of atai Delaware Common Stock.

Reference is made to the sections of this proxy statement/prospectus entitled “The Share Purchase Agreement,” and “The Acquisition–Opinion of Guggenheim Securities” beginning on pages 74 and 58 for a detailed description of the Acquisition and the risks associated with the Acquisition.

Because the consummation of the Acquisition requires shareholder approval under Dutch law, it is proposed that, subject to the adoption of each of the Share Issuance Proposal, the Director Nominee Proposals and the Governing Documents Proposal, also within the meaning of Section 2:107a of the DCC, the Extraordinary General Meeting approves the consummation of the Acquisition by atai in accordance with the terms of the Share Purchase Agreement.

The Acquisition Proposal is conditioned on the adoption of each of the Share Issuance Proposal, the Director Nominee Proposals and the Governing Documents Proposal. Therefore, if any of the Share Issuance Proposal, the Director Nominee Proposals and the Governing Documents Proposal is not adopted, the Acquisition Proposal will have no effect, even if adopted by atai’s shareholders.

The Board unanimously recommends a vote “FOR” the Acquisition Proposal as set forth in this Proposal 1.

In addition to the Acquisition Proposal, atai’s shareholders are being asked to approve, for purposes of complying with the applicable provisions of Nasdaq Listing Rule 5635(a), the issuance of Consideration Shares in connection with the Acquisition pursuant to the terms of the Share Purchase Agreement.

Rule 5635(a) requires shareholder approval with respect to issuances of ordinary shares, among other instances, when the shares to be issued are being issued in connection with the acquisition of the stock or assets of another company and are equal to 20% or more of the outstanding shares of ordinary shares of the acquiror before the issuance.

The Share Issuance Proposal is conditioned on the adoption of each of the Acquisition Proposal, the Director Nominee Proposals and the Governing Documents Proposal. Therefore, if any of the Acquisition Proposal, the Director Nominee Proposals and Governing Documents Proposal is not adopted, the Share Issuance Proposal will have no effect, even if adopted by atai’s shareholders.

The Board unanimously recommends a vote FOR the Share Issuance Proposal as set forth in this Proposal 2.

The Board (at that time functioning as a supervisory board) has made a binding nomination to appoint Mr. Cosmo Feilding-Mellen, subject to the consummation of the Acquisition, as a non-executive director of the Company to serve in such capacity for a period ending at the end of the Annual General Meeting of shareholders of the Company (or atai Delaware, as applicable) to be held in 2028 or until his earlier death, resignation or removal, as applicable.

Mr. Cosmo Feilding-Mellen, 40, is the Co-Founder and Chief Executive Officer of Beckley Psytech since December 2019 and also serves on its board of directors. Mr. Feilding-Mellen is a drug development entrepreneur and, in 2016, co-founded Beckley Research & Innovations to develop ethical business models focused on scientific research into medical cannabis and psychedelics. Mr. Feilding-Mellen subsequently served as Co-Founder and Managing Director of Beckley Canopy Therapeutics, a cannabinoid-based drug development company from January 2018 to October 2019, and Spectrum Biomedical UK, a medical cannabis distribution company from January 2019 to March 2020. In 2019, both of these companies were acquired by Canopy Growth Corporation, at the time the world’s largest medical cannabis company. Mr. Feilding-Mellen completed his undergraduate and master’s degrees at the University of Oxford. We believe that Mr. Feilding-Mellen is qualified to serve as a non-executive director because of his experience as a founder of biopharmaceutical companies and his deep institutional knowledge of Beckley Psytech, which we believe would help assess and unlock synergies in the Combined Group. See “Security Ownership of Certain Beneficial Owners and Management” for information about the number of shares in the capital of the Company Mr. Feilding-Mellen beneficially owns.

This Proposal 3A is conditioned on the consummation of the Acquisition and therefore requires the adoption of each of Proposal 1 (the Acquisition Proposal), Proposal 2 (the Share Issuance Proposal) and Proposal 4 (the Governing Documents Proposal). Therefore, if any of the Acquisition Proposal, the Share Issuance Proposal and Governing Documents Proposal is not adopted, this Proposal 3A will have no effect, even if adopted by atai’s shareholders. For the avoidance of doubt, if each of the Acquisition Proposal, the Share Issuance Proposal and the Governing Documents Proposal is adopted, Mr. Feilding-Mellen shall serve as a non-executive director of the Company with effect from the consummation of the Acquisition and until the end of the Annual General Meeting of shareholders of the Company (or atai Delaware, as applicable) to be held in 2028 or until his earlier death, resignation or removal, as applicable.

The Board unanimously recommends a vote “FOR” the appointment of Mr. Cosmo Feilding-Mellen as a non-executive director of the Company as set forth in this Proposal 3A.

The Board (at that time functioning as a supervisory board) has made a binding nomination to appoint Dr. Robert Hershberg, subject to the consummation of the Acquisition, as a non-executive director of the Company to serve in such capacity for a period ending at the end of the Annual General Meeting of shareholders of the Company (or atai Delaware, as applicable) to be held in 2028 or until his earlier death, resignation or removal, as applicable.

Dr. Robert Hershberg, 62, was appointed to the board of directors at Beckley Psytech in June 2024. He is Co-Founder, President, Chief Executive Officer and Chairman of the Board of Directors at Hillevax Inc. (NASDAQ: HLVX), a biopharmaceutical company focused on the development and commercialization of novel vaccine candidates, since September 2020. He has been a Venture Partner with Frazier Healthcare Partners (“Frazier”) since April 2020 and has been working with Frazier and its portfolio companies as an Entrepreneur-in-Residence, Senior Advisor, and executive for the last 14 years. Dr. Hershberg was formerly Co-Founder, President and Chief Executive Officer of VentiRx Pharmaceuticals, a Frazier-founded company developing a small molecule therapeutic to activate the immune system against solid tumours, from 2006 to 2016. During his time at VentiRx, Dr. Hershberg led the company through its partnership with Celgene, a pharmaceutical company developing cancer and immunology drugs. He joined Celgene in 2014 to lead their efforts in Immuno-Oncology, was promoted to Executive Vice President and Chief Scientific Officer in 2016 and was subsequently Executive Vice President and Head of Business Development and Global Alliances and served as a member of the Executive Committee until the acquisition of Celgene by Bristol-Myers Squibb in 2019. Dr. Hershberg has been on the board of Adaptive Biotechnologies (NASDAQ: ADPT) since June 2013, including as a member of its compensation committee since December 2019 and on the board of Recursion Pharmaceuticals (NASDAQ:RXRX), including as a member of its compensation committee, since June 2021, he was also a member of the board of Fate Therapeutics (NASDAQ: FATE) from April 2021 through June 2024 and of Nanostring Technologies (NASDAQ:NSTG) from June 2019 through June 2023. Dr. Hershberg completed his undergraduate and medical degrees at the University of California, Los Angeles and received his Ph.D. at the Salk Institute for Biological Studies. We believe that Dr. Hershberg is qualified to serve as a non-executive director because of his extensive experience in biopharmaceutical industry. See “Security Ownership of Certain Beneficial Owners and Management” for information about the number of shares in the capital of the Company Dr. Hershberg beneficially owns.

This Proposal 3B is conditioned on the consummation of the Acquisition and therefore requires the adoption of each of Proposal 1 (the Acquisition Proposal), Proposal 2 (the Share Issuance Proposal) and Proposal 4 (the Governing Documents Proposal). Therefore, if any of the Acquisition Proposal, the Share Issuance Proposal and Governing Documents Proposal is not adopted, this Proposal 3B will have no effect, even if adopted by atai’s shareholders. For the avoidance of doubt, if each of the Acquisition Proposal, the Share Issuance Proposal and the Governing Documents Proposal is adopted, Dr. Hershberg shall serve as a non-executive director of the Company with effect from the consummation of the Acquisition and until the end of the Annual General Meeting of shareholders of the Company (or atai Delaware, as applicable) to be held in 2028 or until his earlier death, resignation or removal, as applicable.

The Board unanimously recommends a vote “FOR” the appointment of Dr. Robert Hershberg as a non-executive director of the Company as set forth in this Proposal 3B.

Our Board is currently composed of eight members, consisting of one executive director and seven non-executive directors. As set forth in Proposal 3A and Proposal 3B (together, “Proposal 3”), the Board (at that time functioning as a supervisory board) has made a binding nomination to appoint each of Mr. Cosmo Feilding-Mellen and Dr. Robert Hershberg as a non-executive director, subject to the consummation of the Acquisition, to serve in such capacity for a period ending at the end of the annual general meeting of shareholders of the Company to be held in 2028 or until his earlier death, resignation or removal, as applicable. Our directors do not have a retirement age requirement under the Articles of Association. If Mr. Feilding-Mellen and Dr. Hershberg are appointed as non-executive directors at the Extraordinary General Meeting, it is anticipated that the Board will consist of ten members immediately following the consummation of the Acquisition. Each of Mr. Feilding-Mellen and Dr. Hershberg has consented to being named in this proxy statement/prospectus and serving on the Board if elected. The Board has no reason to believe that either of Mr. Feilding-Mellen and Dr. Hershberg will be unable to serve as a director if elected.

The following table sets forth the names of our current directors and the director nominees, and their respective ages, the year each member has started their current term (including their respective terms served as a supervisory director of atai), or will start their term, if elected, and the year of expiration of their respective current terms as non-executive directors or expected year of expiration, if elected:

Biographical information for Mr. Cosmo Feilding-Mellen and Dr. Robert Hershberg, each a nominee for election at the Extraordinary General Meeting, is set forth under Proposal 3A and Proposal 3B.

Sabrina Martucci Johnson founded Dare Bioscience, Inc., a public biopharmaceutical company engaged in the development of novel therapies that expand treatment options for women, and has served on the board of directors and as Chief Executive Officer since 2015. From January 2018 to April 2022, Ms. Johnson served on the board of directors of Aethlon Medical, Inc., a public company developing immunotherapeutic technologies to combat infectious disease and cancer, and as a member of its Audit Committee, Compensation Committee, and Nominating and Corporate Governance Committee. Ms. Johnson received a Master of International Management degree from the American Graduate School of International Management, an MSc. in biochemical engineering from University College London and a BSc. in biomedical engineering from Tulane University. We believe that Ms. Johnson is qualified to serve on our Board because of her experience in building successful companies and launching innovative products into specialty markets.

Amir Kalali, M.D. is the Co-Chair of the Decentralized Trials and Research Alliance since 2020 and Founding Chairman and Chief Curator of the CNS Summit, a forum focused on the future of life sciences, since 2011. He is also the Founding Chairman and sits on the Executive Committee of the International Society for CNS Drug Development, an independent non-profit focused on improving central nervous system drug development, founded

in 2022. In addition, Dr. Kalali is a Professor of Psychiatry at the University of California San Diego and Editor of the journal, Innovations in Clinical Neuroscience. He previously served as the Global Head of the Neuroscience Center of Excellence at IQVIA (formerly Quintiles and IMS Health, Inc.), a publicly traded health information technology company, from 1997 to 2017. From January 2004 to January 2011, Dr. Kalali served as a member of the board of directors, as well as the Compensation Committee and Nominating Committee, of Cypress Bioscience, a public pharmaceutical company. Dr. Kalali received his M.D. from University College London and his MRCPSych from the Royal College of Psychiatrists. We believe that Dr. Kalali is qualified to serve on our Board because of his more than 20 years of experience in the life sciences and technology fields, as well as his involvement in numerous drug development programs.

Andrea Heslin Smiley has served in various roles at VMS Biomarketing, Inc., or VMS, since 2008, most recently as President and Chief Executive Officer since January 2011. Prior to joining VMS, from 1996 to 2008, Ms. Smiley served in various roles at Eli Lilly and Company, most recently as Vice President, Osteoporosis Business Unit. Ms. Smiley currently serves as a director and member of the Audit Committee of Rockwell Medical, Inc., a public biopharmaceutical company, and as a director of Agent Capital LLC. Ms. Smiley previously served as a director of Assertio Therapeutics, Inc., a public commercial pharmaceutical company, from May 2020 to January 2021, and Zyla Life Sciences, a public specialty commercial pharmaceutical company, from January 2017 to May 2020, where she was also the Chair of the Nominating and Governance Committee and a member of the Audit Committee. We believe that Ms. Smiley is qualified to serve on our Board because of her more than 25 years of commercialization and management experience in the biopharmaceutical industry in both public and private companies.

Christian Angermayer is the founder of Apeiron Investment Group Ltd., which he founded in 2012. Mr. Angermayer is also the founder of Presight Capital Management Company, L.L.C. and has served as General Partner since 2019. Mr. Angermayer also serves on the board of directors of several private companies, including, since 2019, Cambrian Biopharma, Inc. and Rejuveron Life Sciences AG. We believe that Mr. Angermayer is qualified to serve on our Board because of his extensive finance and life sciences industry experience.

Scott Braunstein, M.D. has served as President and Chief Executive Officer of Marinus Pharmaceuticals, Inc. (Nasdaq: MRNS) since August 2019 and has served as a member of the Marinus board of directors (the “Marinus Board”) since September 2018, including as chair of the Marinus Board from November 2022 and as Executive Chair from February 2019 to August 2019. Dr. Braunstein brings over 20 years of knowledge and experience from diverse biotechnology and pharmaceutical industry vantage points. He has served as an operating partner at Aisling Capital since 2015. From 2015 to 2018, he served as Senior Vice President, Strategy and Chief Operating Officer at Pacira Pharmaceuticals, Inc. (Nasdaq: PCRX), a specialty pharmaceutical company focused on the acute care setting. Prior to Pacira, he served as a healthcare portfolio manager at Everpoint Asset Management from 2014 to 2015 and spent 12 years with J.P. Morgan Asset Management as a healthcare analyst and managing director in the U.S. Equity team, and as portfolio manager of the JP Morgan Global Healthcare Fund responsible for managing investments in pharmaceuticals, biotechnology, and medical devices. Dr. Braunstein is currently on the board of directors of Caribou Biosciences, Inc. (Nasdaq: CRBU) and Trevena Inc. (Nasdaq: TRVN). Dr. Braunstein previously served on the boards of directors of Esperion Therapeutics, Inc. (Nasdaq: ESPR) (June 2015 to April 2020), Ziopharm Oncology Inc. (Nasdaq: ZIOP) (September 2018 to November 2020), Protara Therapeutics, Inc. (f/k/a ArTara Therapeutics, Inc.) (Nasdaq: TARA) (May 2018 to July 2020) and Constellation Pharmaceuticals, Inc. (formerly Nasdaq: CNST) (February 2018 to July 2021). Dr. Braunstein began his career as a practicing physician at the Summit Medical Group and as an assistant clinical professor at Albert Einstein College of Medicine and Columbia University Medical Center. He earned his medical degree from the Albert Einstein College of Medicine and his undergraduate degree at Cornell University. We believe Dr. Braunstein is qualified to serve on our Board because of his extensive leadership experience in the pharmaceutical industry and healthcare portfolio management, including his role as the President and Chief Executive Officer of Marinus Pharmaceuticals, Inc.

Laurent Fischer, M.D. has served as the chief executive officer of Adverum Biotechnologies, Inc. (Nasdaq: ADVM) since June 2020 and its president and CEO since June 2021. He was chairman of the board of CTI Biopharma from 2017 until its acquisition by Swedish Orphan Biovitrum in June 2023. Dr. Fischer served as senior vice president, head of the liver therapeutic area at Allergan PLC, a global pharmaceutical company, from November 2016 to June 2020, in which role he was responsible for the Liver Therapeutic R&D pipeline. Dr. Fischer served as chief executive officer of Tobira Therapeutics, a clinical-stage biopharmaceutical company from December 2013 until Allergan acquired Tobira Therapeutics in November 2016, in which role he was responsible for

taking the company public, completing the first study in NASH demonstrating an anti-fibrotic effect and selling the company to Allergan. Prior to Tobira, he served as chairman and chief executive officer of Jennerex, Inc., from June 2012 to March 2014, until its acquisition by SillaJen Biotherapeutics, Inc. Prior to Jennerex, he was co-founder, president and chief executive officer of Ocera Therapeutics from January 2005 to June 2012 and president and chief executive officer of Auxeris Therapeutics, Inc. from 2003 to 2004. Dr. Fischer serves on the board of directors at Mirum Pharmaceuticals, Inc. since June 2019. Dr. Fischer also serves on the board of directors of Lycia Therapeutics, a private company founded by Caroly Bertozzi, since December 2019, and as chairman of private company Teal since October 2023. Over the span of his career, Dr. Fischer has held roles of increasing responsibility at companies, including, RXCentric, Inc. (now part of Allscripts Healthcare Solutions, Inc.), MedVantx Inc., Dupont Pharmaceuticals, Dupont-Merck and F. Hoffmann-La Roche. Dr. Fischer earned an undergraduate degree from the University of Geneva and his medical degree from the Geneva Medical School, Switzerland. We believe Dr. Fischer is qualified to serve on our Board because of his extensive leadership experience as an executive in the pharmaceutical industry and knowledge of biopharmaceuticals, including his position as the Chief Executive Officer of Adverum Biotechnologies, Inc.

Srinivas Rao, M.D., Ph.D. is the Company’s co-founder and has served as the Company’s Chief Executive Officer since January 1, 2025, and co-Chief Executive Officer since June 1, 2024. Prior to that, Dr. Rao served as the Company’s Chief Scientific Officer since April 2019. Prior to joining the Company, Dr. Rao was the Chief Medical Officer at Axial Biotherapeutics, Inc. from August 2017 to March 2019 and the Chief Medical Officer at Depomed, Inc. from July 2014 to July 2017. Prior to that, he served as Executive Vice President and Head of Neuroscience at Retrophin from December 2013 to March 2014 and Chief Executive Officer at Kyalin Biosciences Inc. from October 2011 to December 2013. He has held leadership positions at a number of biotechnology companies, including Kalyra Pharmaceuticals, Avelas Biosciences, Sova Pharmaceuticals, ReVision Therapeutics and Cypress Bioscience, Inc. Dr. Rao received his Ph.D. in Neuropharmacology, his M.D. in Internal Medicine, his M.S. in Electrical Engineering and his Bachelor of Science in Electrical Engineering from Yale University. We believe Dr. Rao is qualified to serve on our Board because of his extensive experience in the biopharmaceutical industry, medical research and background knowledge of the Company as its co-founder and current chief executive officer as well his prior role as chief scientific officer.

Mr. John Hoffman currently serves as Chief Operating Officer of Northern Data AG since February 2025. Mr. Hoffman brings nearly 20 years of experience as an investment banker and capital markets advisor. He most recently served as Managing Director in the equity capital markets groups at RBC Capital Markets from June 2023 to February 2025 and previously at Credit Suisse from June 2012 to June 2023. Across his investment banking career, John has advised boards and management teams on more than 200 growth capital IPOs that have raised in excess of USD 50 billion in cumulative proceeds, as well as international cross-listings, mergers, spin-offs, and other strategic transactions for disruptive growth companies. Mr. Hoffman is a graduate of the University of Richmond and is a CFA charterholder. We believe that Mr. Hoffman is qualified to serve on our Board because of his extensive experience in finance and investment banking as well as his substantial experience advising boards of directors and management teams. See “Security Ownership of Certain Beneficial Owners and Management” for information about the number of shares in the capital of the Company Mr. Hoffman beneficially owns.

There are no family relationships among any of our executive officers or directors, including our director nominees.

The Articles of Association currently provide that the name of the Company is atai Life Sciences N.V. We have agreed with Beckley Psytech pursuant to the Share Purchase Agreement to change our name to Atai Beckley N.V., subject to the approval of our shareholders and the consummation of the Acquisition. For that reason, the Company proposes to amend the Company’s name, as included in the Articles of Association, through the execution of a deed of amendment to the Articles of Association in the form attached to this proxy statement/prospectus as Annex G-1 (English translation attached as Annex G-2) (the “Deed of Amendment I”).

If this Governing Documents Proposal is adopted, each lawyer, candidate civil law notary and civil law notary of NautaDutilh N.V. shall be authorized to execute the Deed of Amendment I.

The Governing Documents Proposal is conditioned on the adoption of each of the Acquisition Proposal, the Share Issuance Proposal and the Director Nominee Proposals. Therefore, if any of the Acquisition Proposal, the Share Issuance Proposal and the Director Nominee Proposals is not adopted, the Acquisition cannot be consummated and the Governing Documents Proposal will have no effect, even if adopted by atai’s shareholders.

The Board unanimously recommends a vote “FOR” the Governing Documents Proposal as set forth in this Proposal 4.

Reference is made to the section of this proxy statement/prospectus entitled “The Redomiciliation” beginning on page 89 for a detailed description of the Redomiciliation and the risks associated with the Redomiciliation.

The Board proposes to atai shareholders to enter into the LuxCo Merger in accordance with the Merger Plan. The LuxCo Merger is the initial step required to change the legal domicile of atai Life Sciences N.V. from the Netherlands to the State of Delaware, upon which atai will continue as a Delaware corporation and atai shareholders would hold shares in atai Delaware rather than in a Dutch company. If the atai shareholders adopt the Redomiciliation Proposal and the Redomiciliation Withdrawal Rights Proposal, and the other conditions to completion of the Redomiciliation are satisfied (or waived by the Board), atai anticipates that, as soon as practicable thereafter, it will complete (i) the LuxCo Merger in accordance with Sections 2:309 and 2:333b(1) of the DCC and articles 1025-1 et seq. of the Luxembourg Companies Act and (ii) subsequently, the Delaware Conversion in accordance with articles 1061-1 et seq. of the Luxembourg Companies Act and the domestication procedures of Section 388 of the General Corporation Law of the State of Delaware. For the avoidance of doubt, as part of the Redomiciliation Proposal atai shareholders are only being asked to enter into the LuxCo Merger and are not being asked to approve the Delaware Conversion. If the Redomiciliation Proposal is adopted by atai shareholders (and the other conditions to completion of the Redomiciliation are satisfied or waived by the Board), then atai expects to adopt, as atai LuxCo’s sole shareholder, all requisite shareholder approvals and other resolutions in respect of the Delaware Conversion prior to the effectiveness of (and subject to the completion of) the LuxCo Merger.

After the Redomiciliation is complete, (i) the Proposed Charter and Proposed Bylaws, copies of which are attached to this proxy statement/prospectus as Annexes J-1 and J-2, respectively, will come into effect and (ii) atai shareholders will hold one share of atai Delaware Common Stock for each one Ordinary Share owned immediately prior to the Redomiciliation (except for those Ordinary Shares held by any atai shareholder who validly exercises his, her or its withdrawal rights under Dutch law). The business, assets, liabilities, directors and officers of atai Delaware are expected to be the same as the business, assets, liabilities, directors and officers of atai immediately prior to the Redomiciliation. For more information, please see the section of this proxy statement/prospectus entitled “The Redomiciliation.”

The Redomiciliation Proposal is not conditioned on any other proposals contained in this proxy statement/prospectus.

The Board unanimously recommends a vote “FOR” the Redomiciliation Proposal as set forth in this Proposal 5.

Reference is made to the section of this proxy statement/prospectus entitled “The Redomiciliation” beginning on page 89 for a detailed description of the Redomiciliation and the associated withdrawal rights for atai shareholders.

The Board proposes to atai shareholders to adopt the Redomiciliation Withdrawal Rights Proposal to amend the Articles of Association in connection with the LuxCo Merger to include a formula on the basis of which cash compensation to atai’s shareholders who validly exercise their withdrawal right in connection with the LuxCo Merger can be readily determined through the execution of the Deed of Amendment II, a copy of which is attached to this proxy statement/prospectus as Annex H-1 (English translation attached as Annex H-2).

If this Redomiciliation Withdrawal Rights Proposal is adopted, each lawyer, candidate civil law notary and civil law notary of NautaDutilh N.V. shall be authorized to execute the Deed of Amendment II.

The Redomiciliation Withdrawal Rights Proposal is not conditioned on any other proposals contained in this proxy statement/prospectus.

The Board unanimously recommends a vote “FOR” the Redomiciliation Withdrawal Rights Proposal as set forth in this Proposal 6.

Reference is made to the section of this proxy statement/prospectus entitled “The Redomiciliation” beginning on page 89 for a detailed description of the Redomiciliation and the associated withdrawal rights for atai shareholders.

As indicated elsewhere in this proxy statement/prospectus, if any atai shareholder (irrespective of where such shareholder resides) exercises his, her or its withdrawal rights under Dutch law in connection with the LuxCo Merger then it is possible that the LuxCo Merger shall be treated as a taxable disposition for UK tax purposes for all atai shareholders who are a resident in the United Kingdom, unless the Ordinary Shares which would be cancelled pursuant to the exercise of such withdrawal rights upon the completion of the LuxCo Merger would first be converted into a separate class of shares.

In connection with the foregoing, the Board proposes to atai shareholders to adopt the Redomiciliation Share Conversion Proposal to amend the Articles of Association in connection with the LuxCo Merger to provide that any Ordinary Shares which would be cancelled pursuant to the exercise of withdrawal rights under Dutch law upon the completion of the LuxCo Merger, shall convert into B shares in the capital of atai with effect from the moment immediately preceding the effectiveness of the LuxCo Merger through the execution of the Deed of Amendment III, a copy of which is attached to this proxy statement/prospectus as Annex I-1 (English translation attached as Annex I-2). Upon completion of the LuxCo Merger, the B shares shall automatically cancel by operation of law. If no withdrawal rights under Dutch law are properly exercised, then this amendment shall not be effected.

If this Redomiciliation Share Conversion Proposal is adopted, each lawyer, candidate civil law notary and civil law notary of NautaDutilh N.V. shall be authorized to execute the Deed of Amendment III.

The Redomiciliation Share Conversion Proposal is not conditioned on any other proposals contained in this proxy statement/prospectus.

The Board unanimously recommends a vote “FOR” the Redomiciliation Share Conversion Proposal as set forth in this Proposal 7.

atai Life Sciences N.V., a company incorporated in the Netherlands, is a clinical-stage biopharmaceutical company on a mission to develop highly effective mental health treatments to transform patient outcomes. atai’s Ordinary Shares are listed on Nasdaq under the ticker symbol “ATAI.” atai’s principal executive offices are located at Prof. J.H. Bavincklaan 7, 1183 AT Amstelveen, the Netherlands, and its telephone number is +31 20 793 2536.

Beckley Psytech Limited, incorporated in England and Wales, is a clinical-stage private biopharmaceutical company dedicated to developing a portfolio of psychedelic-based treatments aimed at improving patient outcomes and alleviating the burden of mental health conditions on individuals, healthcare systems, and society as a whole. Beckley Psytech’s principal executive offices are located at Beckley Park, Beckley, Oxford, England OX3 9SY and its telephone number is +44 18 6598 7633.

atai Life Sciences N.V., a company incorporated in the Netherlands, is a clinical-stage biopharmaceutical company on a mission to develop highly effective mental health treatments to transform patient outcomes. atai’s Ordinary Shares are listed on Nasdaq under the ticker symbol “ATAI.” atai’s principal executive offices are located at Prof. J.H. Bavincklaan 7, 1183 AT Amstelveen, the Netherlands, and its telephone number is +31 20 793 2536.

atai Life Sciences Luxembourg S.A. is a newly formed Luxembourg public limited liability company (société anonyme) having its registered office at 63, rue de Rollingergrund, L-2440 Luxembourg, Grand Duchy of Luxembourg and registered with the Luxembourg Register of Commerce and Companies under number B298928. atai LuxCo has only nominal assets and capitalization and has not engaged in any business or other activities other than in connection with its formation and the Redomiciliation. Subject to the receipt of shareholder approval of the Redomiciliation Proposal, atai will merge with and into atai LuxCo, and atai LuxCo will convert to atai Delaware.

The following discussion contains certain information about the Acquisition. This discussion is subject, and qualified in its entirety by reference, to the Share Purchase Agreement, a copy of which is attached as Annex A to this proxy statement/prospectus. You should read this entire proxy statement/prospectus, including the Share Purchase Agreement, before making any voting decision.

Upon the terms and subject to the conditions set forth in the Share Purchase Agreement, atai agreed to acquire from the shareholders of Beckley Psytech the entire issued share capital of Beckley Psytech not already owned by atai by issuing to the Sellers 105,044,902 Ordinary Shares. Upon completion of the Acquisition, Beckley Psytech and its subsidiaries will be wholly-owned subsidiaries of atai.

The Share Purchase Agreement provides that, prior to Closing, the Sellers and atai shall use all reasonable endeavors to procure that the Beckley Carve-Out takes effect in accordance with the Beckley Carve-Out Steps Plan. The Beckley Carve-Out Steps Plan envisages that Eleusis and its subsidiaries will be carved out of the Beckley Group by way of a dividend in specie of all of the issued shares in Eleusis such that the holders of Beckley Shares shall each receive a pro-rata equity holding in Eleusis. The Beckley Carve-Out is not a condition to the Closing and there is no guarantee that the Beckley Carve-out will occur prior to the Closing or that it will occur at all.

At the Closing, 100% of the equity interests of Beckley Psytech issued and outstanding immediately prior to the Closing and not already owned by atai will be acquired by atai, and the Sellers and, if applicable, certain Beckley Optionholders, will receive the right to receive from atai within five business days of the Closing an aggregate of 105,044,902 fully-paid and nonassessable Ordinary Shares.

atai may elect to grant (i) Consideration Shares, (ii) Replacement Awards or (iii) a combination of the foregoing to Beckley Optionholders who hold vested and in the money Beckley Options in exchange for the cancellation of such Beckley Options, provided that the Beckley Options held by any Beckley Optionholder who is a former employee or former contractor of Beckley, or a non-natural person, shall lapse at Closing unless exercised (and the exercise price and related taxes paid) prior to Closing. The total number of Consideration Shares to be issued to the Sellers (and Beckley Optionholders, if applicable) is subject to the following adjustments:

The following chronology summarizes the key meetings and events that led to the signing of the Share Purchase Agreement. The following chronology does not purport to catalogue every conversation or correspondence by and among members of atai’s supervisory or management boards, Beckley Psytech, or their respective advisors, or any other person.

atai and Beckley Psytech both operate in the psychedelic-based therapies market, developing treatments to improve patient outcomes for mental health disorders. The terms of the Share Purchase Agreement were the result of extensive negotiations between atai, Beckley Psytech and their respective affiliates, shareholders and representatives. The following is a brief description of certain key events and contacts that led to the signing of the Share Purchase Agreement.

Over the years, in the ordinary course of business and from time to time, atai’s supervisory and management boards have evaluated and considered a variety of strategic opportunities as part of atai’s long-term strategy to enhance value for its shareholders. These evaluations have included potential mergers, acquisitions, collaborations, partnerships, and other business combinations, with a focus on advancing atai’s mission to develop innovative mental health treatments. atai has regularly reviewed its clinical development programs, business opportunities, and potential transactions to strengthen its position in the biopharmaceutical industry. The entry into the Share Purchase Agreement

for atai to acquire all of the remaining interests in Beckley Psytech in an all-share transaction, following atai’s prior Series C Investment in Beckley Psytech, aligns with these strategic evaluations and discussions, aimed at transforming patient outcomes in mental health treatment.

On January 3, 2024, atai completed a Series C investment into Beckley Psytech, pursuant to a Subscription and Shareholders’ Agreement, dated as of January 3, 2024 by and among atai, Beckley Psytech, the Beckley Founders, certain founding shareholders and the existing investors in Beckley Psytech, under which atai subscribed for 24,096,385 newly issued Series C preferred shares of Beckley Psytech, par value £0.0001 per share (the “Series C Shares”) for a price per share of $1.66 and an aggregate subscription amount of $39,999,999.10 (the “Series C Investment”). In connection with the Series C Investment, on January 3, 2024, atai acquired 24,096,385 warrants to subscribe for Series C Shares at an exercise price of $2.158 per share.

On January 18, 2024, atai completed an acquisition of an additional 11,153,246 shares in Beckley Psytech for a price per share of approximately $0.8966 and an aggregate consideration of $10,000,000.37, from certain selling shareholders in Beckley Psytech, pursuant to a Share Purchase Deed, dated as of January 18, 2024, by and among atai and such selling shareholders. This resulted in atai holding 35.47% of Beckley Psytech’s issued share capital. The acquired shares were registered in atai’s name on March 11, 2024 following stamping from HMRC. Immediately following registration, these shares were converted to Series C Shares in Beckley Psytech. On May 1, 2024, atai was granted additional warrants to subscribe for 4,393,400 Series C Shares at an exercise price of $1.66 per share.

On May 16, 2024, representatives of atai management engaged in preliminary conversations with representatives of Beckley Psytech management regarding a potential strategic transaction between the two companies. Over the course of the following months through October 2024, representatives of atai management and representatives of Beckley Psytech management held regular calls to discuss the terms of such potential strategic transaction.

On June 13, 2024, atai’s supervisory board met, with representatives of atai management in attendance. Representatives of atai management discussed and provided an update to atai’s supervisory board regarding the outreach with Beckley Psytech regarding a potential strategic transaction, including (i) summarizing ongoing communications between atai management and representatives of Beckley Psytech management, (ii) detailing the results of clinical data generated by Beckley Psytech, (iii) outlining the rationale and potential synergies that could be achieved in connection with a potential strategic transaction, (iv) providing anticipated timings, terms and contemplated outcomes for a potential strategic transaction and (v) discussing recruitment at Beckley Psytech. Representatives of atai management then discussed with atai’s supervisory board the timeline of Beckley Psytech’s clinical readouts, the potential impact of these readouts on Beckley Psytech’s situation and the ability of atai to negotiate terms for a potential strategic transaction in light of these timelines. At the conclusion of the meeting, atai’s supervisory board resolved to support atai management to work towards a non-binding letter of intent regarding the potential Acquisition (the “First Letter of Intent”).

On July 25, 2024, representatives of atai management held a call with representatives of Beckley Psytech management where they discussed a potential strategic transaction between the parties, and the following day, representatives of atai management shared with representatives of Beckley Psytech management certain headline terms of a proposal for atai to acquire the remaining Beckley Psytech shares it did not own. Representatives of atai management and Beckley Psytech management met on multiple occasions over the following weeks to further discuss such proposal.

On August 8, 2024, representatives of atai management shared a draft of the First Letter of Intent with representatives of Beckley Psytech management. The draft provided that the proposed Acquisition would be structured as an acquisition by atai of all of the remaining equity interests in Beckley Psytech, with the Sellers receiving Ordinary Shares as consideration. In addition, the draft contemplated a contingent success payment of additional Ordinary Shares, payable to Beckley Psytech upon the successful completion and positive readout of the Phase 2B clinical study in relation to BPL-003.

In the following days, representatives of Beckley Psytech management and atai management discussed expectations for financial terms and rationale for transacting.

On September 10, 2024 and September 11, 2024, representatives of atai management met with representatives of Beckley Psytech management in New York City. The parties discussed the potential Acquisition and the provisions of the First Letter of Intent.

On September 18, 2024, atai’s supervisory board met, with representatives of atai management and Guggenheim Securities, as the prospective financial advisor to atai, also in attendance. Members of atai management provided a strategic update regarding the Acquisition, outlining (i) the progress made with regards to the signing of the First Letter of Intent, (ii) a potential timeline for the Acquisition, including estimates for obtaining the various regulatory and shareholder approvals, if required, (iii) diligence completed to date and (iv) various remaining workstreams. Members of atai management and atai’s supervisory board then engaged in a discussion regarding (i) Beckley Psytech’s assets and the potential benefits and synergies from the potential Acquisition, (ii) other potential acquirors of Beckley Psytech and (iii) atai’s financing strategy, including how a transaction might impact overall financing for atai. Representatives of atai management then introduced representatives of Guggenheim Securities who provided their preliminary views on atai’s current business model and discussed how an Acquisition of Beckley Psytech could be perceived based on historic precedents. Representatives of each of atai management and Guggenheim Securities engaged in a general discussion regarding the potential Acquisition, including on timing and rationale, certain observed market values and structuring. Representatives of Guggenheim Securities were then excused from the meeting and representatives of atai management discussed with atai’s supervisory board potential advisors for the Acquisition and the engagement letters and business terms of their respective appointments. Following the discussion, atai’s supervisory board approved the engagement of Guggenheim Securities as financial advisor for the potential Acquisition on terms to be negotiated between Guggenheim Securities and atai management.

On October 2, 2024, representatives of atai management held a call with representatives of Beckley Psytech management where a revised First Letter of Intent was presented. On October 8, 2024, representatives of atai management and representatives of Beckley Psytech management met in person at the offices of CMS to discuss the provisions of the revised First Letter of Intent and the proposed Acquisition.

Over the course of October 2024 and into early November 2024, representatives of Beckley Psytech management and atai management shared further revisions of the First Letter of Intent. Discussions focused around (i) the terms of the contingent success payment, (ii) Beckley Psytech and Apeiron’s go-forward representation on atai’s supervisory board following Closing, (iii) the change of name of atai to “atai Beckley” (or similar) at Closing, (iv) the proposed carve-out of certain assets from the Beckley Group in connection with the proposed Acquisition, (v) the treatment of Beckley Optionholders in the proposed Acquisition, (vi) proposals that the Acquisition should be supported by a concurrent private placement of Ordinary Shares, (vii) considerations regarding the pro forma pipeline for the combined entity, and (viii) runway considerations to ensure sufficient funding and operational stability post-Acquisition. On October 8, 2024, representatives of Cantor Fitzgerald & Co., the financial advisor to Beckley Psytech, held a call with representatives of Guggenheim Securities to discuss potential improvements to the financial terms of the proposal.

On November 6, 2024, atai entered into an engagement letter with Guggenheim Securities (the “Guggenheim Securities Engagement Letter”), engaging Guggenheim Securities as financial advisor for the potential Acquisition and placement agent in connection with any potential financing involving Ordinary Shares.

Also on November 6, 2024, representatives of Apeiron, an entity affiliated with the chairman of the supervisory board, Mr. Angermayer, indicated to atai management that, in connection with the potential Acquisition, which would be dilutive to Apeiron, and its anchoring of a potential concurrent private placement equity financing, Apeiron wanted to ensure certain go-forward rights, including (i) the right to appoint future directors to the supervisory board and (ii) registration rights. Separately and in the course of negotiating Mr. Angermayer’s consultancy agreement with atai, Mr. Angermayer indicated his desire to receive warrants or other similar instruments in consideration of his go-forward consultancy services.

On November 12, 2024, certain members of atai’s supervisory board and representatives of atai management discussed the potential Acquisition via teleconference. Updates were provided regarding the First Letter of Intent and the timeline for the potential Acquisition.

On November 14, 2024, representatives of Beckley Psytech management informed representatives of atai management that they had reservations regarding whether to proceed with the proposed Acquisition. Over the course of the second half of November 2024 and into early December 2024, representatives of atai management had a number of conversations with and provided further information and documentation in relation to atai to representatives of Beckley Psytech management to allow Beckley Psytech’s management to grow more comfortable with the proposed Acquisition.

On November 22, 2024, representatives of atai management shared with representatives of Apeiron, including Mr. Angermayer, a draft term sheet seeking to address certain of Apeiron’s requests in connection with the potential Acquisition.

On November 27, 2024, representatives of Apeiron shared to representatives of atai management a revised term sheet requesting certain expansions of the rights included in atai’s initial draft and delaying the private placement equity financing obligation until following the closing of the potential Acquisition. From November 2024 through the announcement of the Acquisition, representatives of Apeiron and atai continued to have discussions in respect of the requested rights described herein.

On December 3, 2024, atai’s supervisory board met, with representatives of atai management in attendance. At the outset of the meeting, atai’s supervisory board ratified the establishment of a committee of atai’s supervisory board to negotiate and approve the contemplated Acquisition, which would consist of all members of atai’s supervisory board other than Mr. Angermayer, who would be recused given potential conflicts of interest due to the concurrent negotiation of separate rights for his affiliated entity, Apeiron, in connection with the proposed Acquisition. Thereafter, Mr. Angermayer was recused for all portions of supervisory board meetings during which Apeiron’s potential rights or the negotiation process for the proposed Acquisition was discussed. atai management provided an update regarding their communications with Beckley Psytech since the prior meeting of atai’s supervisory board, including feedback from representatives of Beckley Psytech management on November 14, 2024 that they had reservations regarding the potential Acquisition. Representatives of atai management then discussed the go-forward strategy with Beckley Psytech, including (i) next steps if Beckley Psytech elected to engage further, (ii) reviewing atai’s current rights as a shareholder in Beckley Psytech and its ability to increase such rights through further stock acquisitions, and (iii) how best to strategically position atai ahead of Beckley Psytech’s read-out of the results of its Phase 2B clinical trial of BPL-003. Questions were asked and answered by members of management and atai’s supervisory board and a full discussion ensued.

On December 18, 2024, representatives of atai management shared initial due diligence requests in respect of the potential Acquisition with representatives of Beckley Psytech management, with further due diligence requests shared on January 6, 2025.

On December 19, 2024, representatives of atai management and their advisors were given access to Beckley Psytech’s virtual data room containing confidential information of Beckley Psytech and Beckley Psytech submitted a list of due diligence questions to atai. Thereafter, and through the date of the Share Purchase Agreement, atai, Beckley Psytech and their respective advisors, including their financial, tax and legal advisors, conducted due diligence investigations of each other’s business. Such due diligence activities included telephone calls and review of materials available in the virtual data room and in electronic copy and focused on various aspects of the businesses, including product pipelines, research and development, clinical safety matters, commercial forecasts, intellectual property, regulatory and legal matters, finance and tax.

Throughout late December 2024, representatives of Beckley Psytech and representatives of atai management traded revised drafts of the First Letter of Intent, agreeing that (i) the carve-out of certain assets from the Beckley Group should be completed prior to Closing rather than following Closing, and (ii) that Mr. Angermayer would serve as an anchor investor in a concurrent private placement of Ordinary Shares. The drafts also reflected ongoing discussions between the parties regarding the structure of atai’s supervisory board following Closing.

On December 23, 2024, atai and Beckley Psytech executed the First Letter of Intent. The First Letter of Intent provided that the Acquisition would be structured as an all-stock business combination whereby atai would issue 75,387,957 Ordinary Shares in consideration for the purchase by atai of the remaining interests in Beckley Psytech. The First Letter of Intent also contemplated a contingent success payment of an additional 29,656,945 Ordinary Shares, payable by atai to Beckley Psytech upon the successful completion and positive readout of the Phase 2B clinical study in relation to BPL-003.

On December 30, 2024, representatives of atai management participated in a video call with representatives of Beckley Psytech management to review timelines and the presentation for a concurrent private placement of Ordinary Shares. On January 3, 2025, representatives of atai management, along with certain of their advisors, held a video call with representatives of Beckley Psytech management to discuss the plans for a private placement of Ordinary Shares concurrent with the proposed Acquisition. Between January 3, 2024 and January 9, 2024 representatives of atai management and Beckley Psytech held further discussions regarding the potential private placement.

On January 10, 2025, Latham & Watkins, as legal counsel to atai, delivered an initial draft of the Share Purchase Agreement to CMS, as legal counsel to Beckley Psytech, reflecting the provisions of the First Letter of Intent. Later that day, atai’s supervisory board, by unanimous consent, resolved to enter into an amendment to the Guggenheim Securities Engagement Letter, revising certain fee arrangements.

On January 15, 2025, representatives of Guggenheim Securities shared with atai’s supervisory board their relationship disclosure letter. Based on such disclosures, atai’s supervisory board determined that there were no conflicts of interest that would affect the ability of Guggenheim Securities to fulfill its responsibilities as financial advisor to atai. Also on the same day, atai and Guggenheim Securities executed an amendment to the Guggenheim Securities Engagement Letter, revising certain fee arrangements.

On January 15, 2025, CMS and Latham & Watkins attended a teleconference along with representatives of atai management and Beckley Psytech management, to discuss the intended treatment of Beckley Optionholders in the potential Acquisition.

On January 15, 2025, CMS sent an initial issues list regarding the first draft of the Share Purchase Agreement to Latham & Watkins, which identified as key issues, among other things, (i) the mechanics applicable to the contingent success payment, (ii) the parties whom would be subject to restrictive covenants following Closing, (iii) the proposed mechanics with respect to the use of Article 22 of the Beckley Articles of Association to require certain Sellers to participate in the Acquisition, and (iv) what constitutes permitted leakage (the “January Issues List”).

On January 16, 2025, Latham & Watkins, at the direction of atai management, sent responses to the January Issues List to CMS, which proposed, among other things (i) which parties would be subject to restrictive covenants following Closing, (ii) that costs incurred by Beckley Psytech in connection with the Acquisition should constitute permitted leakage up to a defined threshold amount, and (iii) certain mutually agreeable revisions to the contingent success payment and dragging shareholder mechanics.

On January 28, 2025, representatives of Beckley Psytech management advised representatives of atai management that they were no longer interested in pursuing the contemplated Acquisition due to, among other reasons, uncertainty around the Combined Group cash runway and the ability of atai to finance around the Acquisition.

On January 29, 2025, representatives of Beckley Psytech management informed representatives of atai management that Beckley Psytech was formally withdrawing from negotiations and terminating the First Letter of Intent.

On February 12, 2025, atai priced a public equity offering resulting in a raise of $59,000,000 in gross proceeds.

On March 6, 2025, atai’s supervisory board met, with representatives of atai management in attendance. Representatives of atai management discussed (i) the potential Acquisition and how it might be possible to re-initiate discussions with Beckley Psytech, (ii) atai’s existing shareholder rights in Beckley Psytech, and (iii) and potential alternative strategic transactions to the Acquisition.

During the final weeks of March 2025, representatives of atai management reached out to representatives of Beckley Psytech management to discuss restarting discussions regarding the potential Acquisition.

On April 15, 2025 and in the days following, representatives of atai management had a number of calls with representatives of Beckley Psytech management to discuss how best to present the deal to Beckley Psytech shareholders and to review potential changes to the First Letter of Intent.

On April 17, 2025, representatives of atai management sent to representatives of Beckley Psytech a proposed second non-binding letter of intent (the “Second Letter of Intent”). The terms of the Second Letter of Intent were substantially consistent with the First Letter of Intent other than removing the contingent success payment payable by atai upon the positive readout of the Phase 2B clinical trial of BPL-003. Throughout the remainder of April, the parties negotiated the terms of the Second Letter of Intent and exchanged multiple drafts. In particular, the parties negotiated (i) the inclusion of termination fees in the Share Purchase Agreement that would be payable by atai to Beckley Psytech if atai elected to terminate the Share Purchase Agreement as a result of (A) Beckley Psytech’s Phase 2B clinical study not meeting agreed efficacy and safety criteria (with such criteria being agreed between the parties over the course of negotiations); or (B) the failure to obtain the Shareholder Approval, (ii) the means by which

such termination fees would be settled by atai, either in cash or by way of the issuance of Ordinary Shares to Beckley Psytech, and (iii) the proposed scope of certain voting agreements that would be entered into by certain atai shareholders concurrently with the signing of the Share Purchase Agreement to vote in favor of the Shareholder Approval.

On May 1, 2025, access to the Beckley Psytech virtual data room was restored for atai management and advisors. On May 5, 2025, the parties executed the Second Letter of Intent, which mirrored the First Letter of Intent other than with respect to, among other things, the inclusion of (i) a modified consideration structure that did not include a contingent success payment and whereby atai would issue 105,044,902 Ordinary Shares in consideration for the purchase by atai of the remaining interests in Beckley Psytech, (ii) a termination fee of $4,000,000 that would be payable by atai if atai terminated the proposed Acquisition due to the data relating to Beckley Psytech’s Phase 2B clinical study in relation to BPL-003 not meeting agreed efficacy and safety criteria, (iii) a termination fee of $10,000,000 that would be payable by atai (up to $5,000,000 of which atai could elect to pay by way of the issuance of Ordinary Shares) if the Shareholder Approval was not obtained, (iv) a requirement that the Sellers enter into lock-up agreements in connection with the proposed Acquisition, (v) an obligation that Apeiron and members of atai’s supervisory and management boards enter into voting agreements to vote in favor of the Shareholder Approval, and (vi) a condition that atai would use its reasonable efforts to procure that (A) the atai executive team and the atai Life Sciences GSOP GbR executive team enter into voting agreements to vote in favor of the Shareholder Approval, and (B) Apeiron enter into a lock-up agreement in connection with the proposed Acquisition. The Second Letter of Intent did not include provisions relating to the proposed concurrent private placement of Ordinary Shares that were included in the First Letter of Intent.

Throughout May 2025, representatives of atai management and representatives of Beckley Psytech management held several planning calls to discuss certain aspects of the potential Acquisition.

On May 8, 2025, representatives of Beckley Psytech management shared initial responses to atai’s due diligence requests and uploaded additional documents to the virtual data room in respect of such requests. Further updates and responses were shared by representatives of Beckley Psytech management throughout May.

Also on May 8, 2025, Guggenheim Securities shared with atai’s supervisory board an updated relationship disclosure letter, which atai’s supervisory board determined did not raise any conflicts of interest that would affect the ability of Guggenheim Securities to fulfill its responsibilities as financial advisor to atai.

Also on May 8, 2025, atai entered into a reinstatement letter to its engagement letter with Guggenheim Securities.

On May 9, 2025, Latham & Watkins delivered a revised draft of the Share Purchase Agreement to CMS and Mayer Brown, LLP, U.S. counsel to Beckley Psytech (“Mayer Brown”), reflecting the provisions of the Second Letter of Intent and taking into consideration the January Issues List. The revised draft provided that (i) there would be no contingent consideration payable to Sellers in connection with the results of Beckley Psytech’s Phase 2B clinical trial of BPL-003 and instead included the Milestone Condition, (ii) costs incurred by Beckley Psytech relating to the Beckley Carve-Out and the Acquisition would be permitted leakage only up to a defined threshold amount, (iii) the Beckley Founders and key members of Beckley Psytech management should be subject to restrictive covenants following Closing, and (iv) certain Sellers would enter into lock-up agreements on or prior to Closing.

On May 12, 2025, Latham & Watkins delivered a further revised draft of the Share Purchase Agreement to CMS and Mayer Brown, including certain revisions relating to matters of Dutch law. In the same correspondence, Latham & Watkins delivered initial drafts of (i) the Voting Agreements, (ii) the Apeiron Voting Agreement, and (iii) a lock-up agreement relating to the lock-up of the Consideration Shares to be received by the Sellers.

On May 13, 2025, CMS sent an issues list regarding the revised draft of the Share Purchase Agreement to Latham & Watkins, which, among other things, (i) provided that all costs incurred by Beckley Psytech relating to the Beckley Carve-Out and the Acquisition should constitute permitted leakage, (ii) agreed that the Beckley Founders would be subject to restrictive covenants, provided that other key members of Beckley Psytech management would not be, (iii) rejected the inclusion of the Warranty Condition, (iv) capped the limitations of liability in respect of a breach by the Beckley Founders of the business warranties in the Share Purchase Agreement at $200,000 for each Founder, and provided that the Beckley Founders should be permitted to settle such claims through the transfer of Ordinary Shares rather than in cash, (v) proposed certain mechanics (A) for the purposes of allocating the Consideration Shares between the Sellers and (B) with respect to the dragging shareholders, (vi) reserved Beckley

Psytech’s position in relation to the treatment of the Beckley Optionholders in the Acquisition, and (vii) proposed that provisions should be included in the Share Purchase Agreement nominating Beckley Psytech’s two nominees to atai’s supervisory board at Closing, with the identity of Beckley Psytech’s second nominee alongside Cosmo Feilding-Mellen to be determined (the “May Issues List”).

On May 15, 2025, CMS sent an initial draft of the disclosure letter to the Share Purchase Agreement to Latham & Watkins. Later that day, at the direction of representatives of atai management, Latham & Watkins sent responses to the May Issues List to CMS. The response (i) reiterated the proposal that costs incurred by Beckley Psytech in relation to the Beckley Carve-Out and the Acquisition should constitute permitted leakage up to a defined threshold amount, (ii) reiterated that the Warranty Condition should be included in the Share Purchase Agreement, (iii) proposed that the limitation of liability in respect of a breach by the Beckley Founders of the business warranties in the Share Purchase Agreement should be limited up to a certain proposed amount in respect of the Beckley Founders, but agreed that any claims could be settled through the transfer of Ordinary Shares rather than in cash, (iv) agreed that pricing mechanics with respect to the allocation of Consideration Shares between the Sellers should be included in the Share Purchase Agreement but reserved atai’s position on the exact VWAP to be used, and (v) reserved atai’s position on the treatment of the Beckley Optionholders.

Between May 15, 2025 and the signing of the Share Purchase Agreement, representatives of atai management and Beckley Psytech management, along with their various advisors, as applicable, held regular diligence discussions regarding each parties’ financial status and intellectual property rights, as well as post-signing disclosure obligations.

On May 16, 2025, CMS sent follow-up responses on the May Issues List to Latham & Watkins. In its response, Beckley Psytech (i) agreed to accept the inclusion of the Warranty Condition in the Share Purchase Agreement, subject to (A) a material adverse effect triggering such condition being defined as having a value in excess of £25,000,000 to the Beckley Group, and (B) the inclusion of a carve-out in the condition in respect of inaccuracies in the warranties relating to the Phase 2B clinical trial of BPL-003 arising between the read-out of data in respect of that trial and Closing, (ii) reiterated that all costs incurred by Beckley Psytech in relation to the Beckley Carve-Out and the Acquisition should be permitted leakage, (iii) stated that Beckley Psytech could accept a lower limitation of liability than was previously proposed by atai for the Beckley Founders in respect of breaches of the business warranties in the Share Purchase Agreement, (iv) accepted that the Beckley Founders would be subject to restrictive covenants following Closing, but reiterated that key members of Beckley Psytech management should not be subject to restrictive covenants, (v) continued to reserve its position in relation to the treatment of Beckley Optionholders, and (vi) accepting that all Sellers (rather than merely a subset) would enter into a lock-up agreement.

On May 19, 2025, CMS, Ernst & Young LLP, as tax advisor to Beckley Psytech, and Latham & Watkins attended a call to discuss the proposed steps to implement the Beckley Carve-Out. Later on May 19, 2025, CMS sent a revised draft of Share Purchase Agreement to Latham & Watkins reflecting the negotiations between the parties over the prior weeks.

On May 21, 2025, atai began initial discussions with select institutional investors regarding a private placement transaction in Ordinary Shares anticipated to be announced simultaneously with the announcement of the Acquisition.

On May 21, 2025, the Beckley Founders and representatives of each of atai, Beckley Psytech, Latham & Watkins, CMS and Mayer Brown participated in a teleconference to discuss the outstanding open points in the Share Purchase Agreement (the “May 21 Call”). The parties discussed and agreed in principle upon (i) the scope of the Warranty Condition, particularly that any material matters relating to the clinical safety of the Phase 2B clinical trial of BPL-003 should not be included in any carve-out in the condition, (ii) that only the Beckley Founders should be subject to restrictive covenants in the Share Purchase Agreement, and (iii) that costs incurred by Beckley Psytech relating to the Beckley Carve-Out and costs relating to the Acquisition should only constitute permitted leakage where such amounts in aggregate were lower than $2,000,000. Earlier in the day, representatives of Beckley Psytech management and atai management held a separate discussion regarding other material open points in the Share Purchase Agreement and agreed (i) upon the mechanics to allocate Consideration Shares between the Sellers, and (ii) that the liability of the Beckley Founders for breaches of the business warranties in the Share Purchase Agreement be limited to 10% of the consideration actually received by the Beckley Founders under the Share Purchase Agreement.

On May 22, 2025, CMS delivered a revised draft of the disclosure letter to the Share Purchase Agreement, which included the specific disclosures made against the warranties given by the Beckley Founders under the Share Purchase Agreement. Following such time through May 27, 2025, CMS, Mayer Brown and Latham & Watkins traded drafts of the disclosure letter and negotiated the key provisions therein.

Also on May 22, 2025, Latham & Watkins delivered to representatives of Apeiron an initial draft of (i) the Registration Rights Agreement, providing certain registration rights in respect of a resale shelf, (ii) the Apeiron Voting Agreement, providing that, among other things, Apeiron would vote in favor of the Acquisition and the Redomiciliation, (iii) the Lock-Up Agreement, providing that Apeiron’s subject securities would be subject to an extended lock-up period, (iv) the Shareholders Rights Agreement, providing that so long as Apeiron maintains ownership of atai securities in excess of certain ownership thresholds, Apeiron would be entitled to select one or more director designees to atai’s supervisory board, and (v) resolutions providing for certain option grants to Mr. Angermayer, as described further in the section captioned “Certain Relationships and Related Party Transactions—Option Grants” of this proxy statement/prospectus. Latham & Watkins delivered further revised drafts of the various Apeiron-related documents to Apeiron over the course of the following several days.

Later on May 22, 2025, Latham & Watkins sent a further revised draft of the Share Purchase Agreement to CMS reflecting the points discussed during the May 21 Call, which revised draft, among other things, (i) revised the liability regimes applicable to both (A) the Beckley Founders (reflecting the agreement between the parties that the liability of the Beckley Founders for breach of the business warranties given by them to atai would be limited to 10% of the consideration actually received by the Beckley Founders), and (B) atai, for breaches of certain warranties given by them under the Share Purchase Agreement, (ii) proposed amendments to certain warranties to be given by atai, and (iii) provided that dragged Sellers would enter into a deed of adherence to the Share Purchase Agreement prior to Closing. Later that day, Latham & Watkins delivered an initial draft of the Registration Rights Agreement to CMS.

On May 23, 2025, CMS and Latham & Watkins exchanged further revised drafts of the Share Purchase Agreement, in which the parties agreed that that lock-up provisions should be included in the Share Purchase Agreement rather than in standalone agreements. The (i) treatment of Beckley Optionholders and (ii) the identity of Beckley Psytech’s second nominee to atai’s supervisory board at Closing, in addition to anticipated nominee Cosmo Feilding-Mellen, remained open points between the parties. Later that day, CMS delivered an initial draft of the Beckley Carve-Out Steps Plan to Latham & Watkins. On that same day, representatives of atai management held an update call with representatives of Beckley Psytech management to discuss the revised transaction documents.

Also on May 23, 2025, atai’s supervisory board, with representatives of atai management, Latham & Watkins and Guggenheim Securities in attendance. Representatives of atai management provided an update on the status of negotiations with Beckley Psytech and presented to the supervisory board for review and approval the Unaudited Prospective Financial Information, including the material assumptions included therein. For a detailed discussion regarding the Unaudited Prospective Financial Information, please see “The Acquisition—Unaudited Prospective Financial Information” beginning on page 69 of this proxy statement/prospectus. Later at this meeting, Guggenheim Securities reviewed its financial analysis of the Consideration Shares to be issued by atai and rendered an oral opinion, confirmed by delivery of a written opinion dated June 2, 2025, to the atai’s supervisory board to the effect that, as of June 2, 2025, and based on and subject to the matters considered, the procedures followed, the assumptions made and various limitations of and qualifications to the review undertaken, the Consideration Shares to be issued by atai in connection with the Acquisition were fair, from a financial point of view, to atai. Latham & Watkins then discussed with the supervisory board their fiduciary obligations in connection with considering and approving the Acquisition. The supervisory board considered the risks and benefits in engaging in the Acquisition as compared to other available strategic alternatives, including remaining as a standalone company. Following discussion, the supervisory board instructed Latham & Watkins and atai management to negotiate final terms on the remaining open points in the transaction documents.

As of May 24, 2025, the remaining issues open in the draft Share Purchase Agreement related to (i) the treatment of Beckley Optionholders and (ii) the identity of Beckley Psytech’s second nominee to atai’s supervisory board, in addition to anticipated nominee Cosmo Feilding-Mellen at Closing. During the following week, the parties turned multiple drafts of the Share Purchase Agreement with respect to the treatment of the Beckley Optionholders, agreeing that (i) the Beckley Optionholders would each become a party to the Share Purchase Agreement by signing a deed of adherence prior to Closing and would surrender all rights under their options pursuant to the terms of the Share Purchase Agreement rather than executing a separate deed of surrender, and (ii) due to the uncertainty around the quantum of taxes that would be payable by atai on behalf of the relevant vested and in the money Beckley

Optionholders when their options were surrendered and exchanged in return for Consideration Shares, atai would have the sole right to elect that such options are surrendered and exchanged in return for either (A) Consideration Shares, or alternatively, (B) Replacement Awards (or a combination of (A) and (B)). The parties also agreed that, subject to being determined as “independent” under the listing rules and corporate governance rules and regulations of Nasdaq, Robert Hershberg would be appointed as Beckley Psytech’s second nominee to atai’s supervisory board at Closing.

On May 25, 2025, atai shared a draft subscription agreement with a potential investor in the June PIPE Financing (“PIPE Investor A”).

On May 27, 2025, Sullivan & Cromwell LLP (“S&C”), as legal counsel for Apeiron, shared revised drafts of the Apeiron Voting Agreement and Registration Rights Agreement with Latham & Watkins, which, among other things, removed the support obligation of Apeiron to vote in favor of the Redomiciliation. In response, representatives of atai management proposed compromise language relating to the support obligations in respect of the Redomiciliation, including conditioning such obligations on the receipt of certain tax confirmations from atai, and at atai management’s direction, Latham & Watkins sent a revised draft of the Apeiron Voting Agreement including such compromise language.

Also on May 27, 2025, Latham & Watkins shared a draft of the Registration Rights Agreement with counsel to PIPE Investor A, pursuant to which PIPE Investor A would become party to the Registration Rights Agreement in connection with the PIPE Financing.

On May 29, 2025, Guggenheim Securities wall crossed a potential investor in the June PIPE Financing (“PIPE Investor B”).

On May 29, 2025, S&C sent revised drafts of the Shareholder Rights Agreement and the Lock-Up Agreement to Latham & Watkins, requesting (i) in respect of the Shareholders Rights Agreement, certain rights relating to the position of chairman of atai’s supervisory board and (ii) in respect of the Lock-Up Agreement, certain exceptions to the lock-up obligations contained in the Lock-Up Agreement. The next day, representatives of atai management discussed with representatives of Apeiron the proposed revisions from S&C and reached an agreement that the option grants to be made to Mr. Angermayer would be approved at the same time as the signing of the Share Purchase Agreement but that requested rights regarding a chairman role would not be accepted. Also on May 30, 2025, Latham & Watkins sent to S&C revised drafts of the Shareholders Rights Agreement and the Lock-Up Agreement reflecting these positions, and otherwise generally accepting the changes previously received, with minor drafting edits.

From May 29, 2025 to June 2, 2025, S&C and Latham & Watkins finalized the Shareholder Rights Agreement, the Lock-Up Agreement and the Voting Agreement.

On May 30, 2025, Guggenheim Securities provided a draft subscription agreement and a draft of the Registration Rights Agreement to PIPE Investor B.

Also on June 1, 2025, atai’s supervisory board and management board, each by separate unanimous consent, resolved to approve (i) the Share Purchase Agreement, the disclosure letter to the Share Purchase Agreement, the Apeiron Voting Agreement, the Voting Agreements and the other transaction documents relating thereto, (ii) the Acquisition, (iii) the convening of the Extraordinary General Meeting, and (iv) certain ancillary matters. The unanimous consent of atai’s supervisory board also included the binding nomination to appoint Cosmo Feilding-Mellen and Robert Hershberg to atai’s supervisory board at Closing.

Separately, on June 1, 2025, atai’s supervisory board and management board, each by separate unanimous consent, resolved to approve (i) the entry into the private placement offering and issuance and sale of the related securities, (ii) certain agreements with Apeiron in connection with the Acquisition, including the Shareholders Rights Agreement and the Lock-Up Agreement, and (iii) the grant of options to Mr. Angermayer.

Also on June 1, 2025, atai entered into an engagement letter with Berenberg Capital Markets LLC to act as placement agent on the June PIPE Financing.

On June 2, 2025, (i) atai, PIPE Investor A and PIPE Investor B entered into subscription agreements relating to the June PIPE Financing, and (ii) atai, Beckley Psytech, the Sellers and Apeiron (as applicable) executed the Share Purchase Agreement, the Lock-up Agreement, the Apeiron Voting Agreement, the Registration Rights Agreement and the Shareholder Rights Agreement and following the execution thereof, atai and Beckley Psytech publicly announced the Acquisition and the June PIPE Financing.

On August 13, 2025, atai and Beckley Psytech entered into a senior promissory note, pursuant to which atai agreed to advance an aggregate principal amount of up to $10.0 million to Beckley Psytech to be used for the achievement of certain development milestones of BPL-003. In connection therewith, atai and the Seller Representative under the Share Purchase Agreement mutually agreed to revise the Share Purchase Agreement to include a second automatic 90-day extension of the Longstop Date in the event that shareholder approval of the Acquisition has not been obtained by the Longstop Date.

In evaluating the Acquisition, atai’s management board and supervisory board (which have been combined to become the Board on June 25, 2025) consulted with atai’s management and legal and financial advisors, and in reaching its decision to approve the Share Purchase Agreement and recommend to atai shareholders the consummation of the Acquisition by atai in accordance with the terms of the Share Purchase Agreement, the Board (and, prior to June 25, 2025, atai’s management board and supervisory board) considered a number of factors and a substantial amount of information, including the following:

The Board (at the time constituted as a separate supervisory board and management board) also weighed the factors described above against a number of risks and other factors identified in its deliberations as weighing negatively against the Acquisition:

This discussion of the information and factors considered by the Board in reaching its conclusions and recommendation summarizes the material factors considered by the Board (and, prior to June 25, 2025, atai’s management board and supervisory board) but is not intended to be exhaustive. In view of the wide variety of factors considered in connection with its evaluation of the Acquisition and the complexity of these matters, the Board (and, prior to June 25, 2025, atai’s management board and supervisory board) did not find it practicable, and did not attempt, to quantify, rank or assign any relative or specific weights to the various factors that it considered in reaching its determination to approve the Share Purchase Agreement, the Acquisition and to recommend that atai shareholders vote in favor of the Acquisition Proposal, the Share Issuance Proposal, the Director Nominee Proposals and the Governing Documents Proposal.

The Board (and, prior to June 25, 2025, atai’s management board and supervisory board) conducted an overall review of the factors described above and considered the factors overall to be favorable to and to support its determination. In considering the factors described above, individual members of the Board (and, prior to June 25, 2025, by atai’s management board and supervisory board) may have given differing weights to different factors.

The Board (at the time constituted as a separate supervisory board and management board) unanimously approved the Share Purchase Agreement. The Board unanimously recommends that atai shareholders vote “FOR” the Acquisition Proposal, the Share Issuance Proposal, the Director Nominee Proposals and the Governing Documents Proposal.

It should be noted that this explanation of the reasoning of the Board (and, prior to June 25, 2025, atai’s management board and supervisory board) and certain information presented in this section is forward-looking in nature and should be read in light of the factors set forth in “Cautionary Note Regarding Forward-Looking Statements” beginning on page 22 of this proxy statement/prospectus.

atai retained Guggenheim Securities as its financial advisor in connection with atai’s possible Acquisition of Beckley Psytech. In selecting Guggenheim Securities as its financial advisor, atai considered that, among other things, Guggenheim Securities is an internationally recognized investment banking, financial advisory and securities firm whose senior professionals have substantial experience advising companies in, among other industries, the biopharmaceutical industry. Guggenheim Securities, as part of its investment banking, financial advisory and capital markets businesses, is regularly engaged in the valuation and financial assessment of businesses and securities in connection with mergers and acquisitions, recapitalizations, spin-offs/split-offs, restructurings, securities offerings in both the private and public capital markets and valuations for corporate and other purposes.

At the May 23, 2025 meeting of atai’s supervisory board, Guggenheim Securities rendered an oral opinion, subsequently confirmed by delivery of a written opinion dated June 2, 2025, to atai’s supervisory board to the effect that, as of that date, and based on and subject to the matters considered, the procedures followed, the assumptions made and various limitations of and qualifications to the review undertaken, the issuance of the Consideration Shares by atai in connection with the Acquisition was fair, from a financial point of view, to atai.

This description of Guggenheim Securities’ opinion is qualified in its entirety by the full text of the written opinion, which is attached as Annex B to this proxy statement/prospectus and which you should read carefully and in its entirety. Guggenheim Securities’ written opinion sets forth the matters considered, the procedures followed, the assumptions made and various limitations of and qualifications to the review undertaken by Guggenheim Securities. Guggenheim Securities’ written opinion, which was authorized for issuance by the Fairness Opinion and Valuation Committee of Guggenheim Securities, is necessarily based on economic, business, capital markets and other conditions, and the information made available to Guggenheim Securities, as of the date of such opinion. Guggenheim Securities has no responsibility for updating or revising its opinion based on facts, circumstances or events occurring after the date of the rendering of the opinion.

In rendering its opinion, Guggenheim Securities did not express any view or opinion as to (i) the prices at which the shares of or other securities or financial instruments of or relating to atai or Beckley Psytech may trade or otherwise be transferable at any time, (ii) the potential effects of volatility in the credit, financial or equity markets on atai or Beckley Psytech, their respective securities or other financial instruments, the Acquisition or (iii) the impact of the Acquisition on the solvency or viability of atai or Beckley Psytech or the ability of atai or Beckley Psytech to pay their respective obligations when they come due.

In reading the discussion of Guggenheim Securities’ opinion set forth below, you should be aware that such opinion (and, as applicable, any materials provided in connection therewith or the summary of Guggenheim Securities’ underlying financial analyses elsewhere in this proxy statement/prospectus):

In connection with rendering its opinion, Guggenheim Securities:

With respect to the information used in arriving at its opinion, Guggenheim Securities noted that:

Guggenheim Securities also noted certain other considerations with respect to its engagement and the rendering of its opinion:

This “Summary of Financial Analyses” presents a summary of the principal financial analyses performed by Guggenheim Securities and presented to atai’s supervisory board in connection with Guggenheim Securities’ rendering of its opinion. Such presentation to atai’s supervisory board was supplemented by Guggenheim Securities’ oral discussion, the nature and substance of which may not be fully described herein.

Some of the financial analyses summarized below include summary data and information presented in tabular format. In order to understand fully such financial analyses, the summary data and tables must be read together with the full text of the summary. Considering the summary data and tables alone could create a misleading or incomplete view of Guggenheim Securities’ financial analyses.

The preparation of a fairness opinion is a complex process and involves various professional judgments and determinations as to the most appropriate and relevant financial analyses and the application of those methods to the particular circumstances involved. A fairness opinion therefore is not readily susceptible to partial analysis or summary description, and taking portions of the financial analyses set forth below, without considering such analyses as a whole, would in Guggenheim Securities’ view create an incomplete and misleading picture of the processes underlying the financial analyses considered in rendering Guggenheim Securities’ opinion.

In arriving at its opinion, Guggenheim Securities:

With respect to the financial analyses performed by Guggenheim Securities in connection with rendering its opinion:

Throughout this section titled “The Acquisition—Opinion of Guggenheim Securities—Summary of Financial Analyses,” the following defined terms are used in connection with Guggenheim Securities’ various financial analyses:

Recap of Beckley Psytech Stand-Alone Financial Analysis. In evaluating the equity value of Beckley Psytech, excluding atai’s existing stake in Beckley Psytech, (such value, “Beckley Psytech Stand-Alone Value”) in connection with rendering its opinion, Guggenheim Securities performed a discounted cash flow analysis. Solely for informational reference purposes, Guggenheim Securities also reviewed selected publicly traded companies and the Beckley Psytech Series C post-money valuation, each as described below.

Beckley Psytech Stand-Alone Value Discounted Cash Flow Analysis. Guggenheim Securities performed a stand-alone discounted cash flow analysis on the forecasted, probability-adjusted, after-tax unlevered free cash flows (after deduction of share based compensation) for Beckley Psytech.

In performing its discounted cash flow analysis with respect to Beckley Psytech:

Guggenheim Securities’ discounted cash flow analysis for the purposes of evaluating Beckley Psytech Stand-Alone resulted in an overall reference range of $251 million to $376 million in equity value.

Other Financial Reviews of Beckley Psytech for Reference Information Purposes. In order to provide context for the financial analyses of Beckley Psytech as described above, Guggenheim Securities undertook additional financial reviews and analyses as summarized below solely for informational reference purposes. As a general matter, Guggenheim Securities did not consider such additional financial reviews and analyses to be determinative methodologies for purposes of its opinion.

Selected Publicly Traded Companies Analysis. Guggenheim Securities reviewed and analyzed the Adjusted Enterprise Value for selected publicly traded companies that Guggenheim Securities deemed relevant for purposes of this analysis.

Guggenheim Securities calculated, among other things, various public market trading Enterprise Values / Adjusted Enterprise Values for the selected publicly traded companies (in the case of the selected publicly traded companies, based on each company’s most recent publicly available financial filings), which are summarized in the table below.

In performing its selected publicly traded companies analysis, Guggenheim Securities selected a reference range of Enterprise Values / Adjusted Enterprise Values and subsequently added Beckley Psytech’s expected net cash balance as of June 30, 2025.

Guggenheim Securities’ selected publicly traded companies analysis resulted in an overall reference range for purposes of evaluating the Beckley Psytech Stand-Alone Value on a public market trading basis of $181 million to $278 million of equity value.

Recap of atai Stand-Alone Financial Analysis. In evaluating atai in connection with rendering its opinion, Guggenheim Securities performed a discounted cash flow analysis. Solely for informational reference purposes, Guggenheim Securities also reviewed the historical trading price range for the Ordinary Shares, selected publicly traded companies and analyst price targets.

atai Stand-Alone Discounted Cash Flow Analysis. Guggenheim Securities performed a stand-alone discounted cash flow analysis of atai excluding its existing stake in Beckley Psytech on the forecasted, probability-adjusted, after-tax unlevered free cash flows (after deduction of share-based compensation) for atai excluding its existing stake in Beckley Psytech and then added the value of atai’s existing stake in Beckley Psytech, (as described above under the caption above “Beckley Psytech Stand-Alone Value Discounted Cash Flow Analysis”).

In performing its discounted cash flow analysis with respect to atai excluding its existing stake in Beckley Psytech:

Guggenheim Securities’ financing-adjusted discounted cash flow analysis for purposes of evaluating the Ordinary Shares on a stand-alone basis resulted in an overall reference range of $1.91 – $2.99 per share.

Other Financial Reviews of atai for Reference Information Purposes. In order to provide certain context for the financial analysis of atai as described above, Guggenheim Securities undertook various additional financial reviews and analyses as summarized below solely for informational reference purposes. As a general matter, Guggenheim Securities did not consider such additional financial reviews and analyses to be determinative methodologies for purposes of its opinion.

atai Historical Trading Range. Guggenheim Securities reviewed atai’s share price closing history over the 52-weeks ending on May 22, 2025. Guggenheim Securities noted that the lowest closing price was $1.06 per share of the Ordinary Shares on October 31, 2024, and the highest closing price was $2.55 per share of the Ordinary Shares on February 12, 2025.

atai Selected Publicly Traded Companies Analysis. Guggenheim Securities reviewed and analyzed the equity value of atai compared to the enterprise value of selected publicly traded companies in the biopharmaceutical industry adjusted for atai’s estimated net cash and investments balance as of June 30, 2025, in order to provide context for a reference range of generally comparable public trading equity values. Guggenheim Securities calculated, among other things, various public market trading enterprise values for the selected publicly traded companies (in the case of the selected publicly traded companies, based on each company’s most recent publicly available financial filings), which are summarized in the table in the preceding section for the “Other Financial Reviews of Beckley Psytech for Reference Information Purposes–Selected Publicly Traded Companies Analysis.”

In performing its selected publicly traded companies analysis with respect to atai, Guggenheim Securities selected a reference range of Enterprise Values, added a range of values corresponding to atai’s existing stake in Beckley Psytech based on the selected publicly traded companies and added atai’s expected net cash and investment balance as of June 30, 2025. Guggenheim Securities then converted the result of the foregoing calculations to per share equity values using fully-diluted outstanding shares (determined using the treasury stock method taking into account outstanding in-the-money convertible promissory notes, outstanding in-the-money options, and in-the-money HSOP options) as provided by, discussed with, and approved for Guggenheim Securities’ use by atai’s senior management.

Guggenheim Securities’ selected publicly traded companies analysis resulted in an overall reference range for purposes of evaluating the Ordinary Shares on a stand-alone public market trading basis of $2.16  – $3.23 per share.

atai Analyst Price Targets. Guggenheim Securities reviewed four selected Wall Street equity research analyst price targets for atai on a stand-alone basis as published prior to May 22, 2025 (the last trading day prior to atai’s supervisory board meeting where Guggenheim Securities rendered its oral opinion).

In assessing the Consideration Shares, Guggenheim Securities calculated a range of implied Consideration Shares utilizing the implied valuation ranges for Beckley Psytech Stand-Alone equity value and atai’s Ordinary Shares from the stand-alone discounted cash flow analysis described above under the captions “Beckley Psytech Stand-Alone Value Discounted Cash Flow Analysis” and “atai Stand-Alone Discounted Cash Flow Analysis” without giving effect to any Synergies or transaction costs.

Guggenheim Securities’ financial analysis resulted in an implied Consideration Shares reference range of 98 – 161 million shares, as compared to the atai/Beckley Psytech Acquisition Consideration Shares of 105 million.

Guggenheim Securities performed pro forma discounted cash flow analysis, as an additional informational analysis, to compare the reference range of per share equity values of the Ordinary Shares on a stand-alone basis resulting from the stand-alone discounted cash flow analysis of atai as described above under the caption “atai Stand-Alone Discounted Cash Flow Analysis” to the reference range of per share implied equity values of the Ordinary Shares on a pro forma basis giving effect to the Acquisition.

Guggenheim Securities calculated the implied discounted cash flow value per share of the Ordinary Shares on a pro forma basis giving effect to the Acquisition, both with and without Synergies. In conducting this analysis without Synergies:

In conducting this analysis with Synergies, Guggenheim Securities replicated the discounted cash flow analysis without Synergies with the following changes:

The comparison of atai’s discounted cash flow value per share on a stand-alone basis to the discounted cash flow value per share on a pro forma basis after giving effect to the Acquisition is set forth in the table below.

Except as described in the summary above, atai did not provide specific instructions to, or place any limitations on, Guggenheim Securities with respect to the procedures to be followed or factors to be considered in performing its financial analyses or providing its opinion. The type and amount of consideration payable in the Acquisition were determined through negotiations between atai and Beckley Psytech and were approved by atai’s supervisory board. The decision to enter into the Share Purchase Agreement was solely that of atai’s supervisory board. Guggenheim Securities’ opinion was just one of the many factors taken into consideration by atai’s supervisory board. Consequently, Guggenheim Securities’ financial analyses should not be viewed as determinative of the decision of atai’s supervisory board with respect to the fairness, from a financial point of view, to atai of the Consideration Shares pursuant to the Acquisition.

Pursuant to the terms of Guggenheim Securities’ engagement, atai has agreed to pay Guggenheim Securities an estimated cash transaction fee of approximately $3.75 million, which is payable upon consummation of the Acquisition. In connection with Guggenheim Securities’ engagement, atai has previously paid Guggenheim Securities a cash milestone fee of $0.5 million that became payable upon the rendering of Guggenheim Securities’ opinion, which will be credited against the foregoing cash transaction fee. In addition, atai has agreed to reimburse Guggenheim Securities for certain expenses and to indemnify Guggenheim Securities against certain liabilities arising out of its engagement. In addition, in June 2025, Guggenheim Securities acted as lead placement agent in the June PIPE Financing, for which atai has previously paid Guggenheim Securities a customary fee. In addition, in July 2025, Guggenheim Securities acted as a joint-lead placement agent in the July PIPE financing, for which atai has previously paid Guggenheim Securities a customary fee.

Aside from its current engagement by atai (including the PIPE Financings mentioned herein), Guggenheim Securities has not been previously engaged during the past two years by atai, nor has Guggenheim Securities been

previously engaged during the past two years by Beckley Psytech, to provide any financial advisory or investment banking services for which Guggenheim Securities received fees. Guggenheim Securities may in the future seek to provide atai and Beckley Psytech or their respective affiliates with financial advisory and investment banking services unrelated to the Acquisition, for which services Guggenheim Securities would expect to receive compensation.

Guggenheim Securities and its affiliates and related entities engage in a wide range of financial services activities for its and their own accounts and the accounts of customers, including but not limited to: asset, investment and wealth management; insurance services; investment banking, corporate finance, mergers and acquisitions and restructuring; merchant banking; fixed income and equity sales, trading and research; and derivatives, foreign exchange and futures. In the ordinary course of these activities, Guggenheim Securities and its affiliates and related entities may (i) provide such financial services to atai, Beckley Psytech, other participants in the Acquisition or their respective affiliates, for which services Guggenheim Securities and its affiliates and related entities may have received, and may in the future receive, compensation and (ii) directly and indirectly hold long and short positions, trade and otherwise conduct such activities in or with respect to loans, debt and equity securities and derivative products of or relating to atai, Beckley Psytech, other participants in the Acquisition or their respective affiliates. Furthermore, Guggenheim Securities and its affiliates and related entities and its or their respective directors, officers, employees, consultants and agents may have investments in atai, Beckley Psytech and other participants in the Acquisition or their respective affiliates.

Consistent with applicable legal and regulatory guidelines, Guggenheim Securities has adopted certain policies and procedures to establish and maintain the independence of its research departments and personnel. As a result, Guggenheim Securities’ research analysts may hold views, make statements or investment recommendations and publish research reports with respect to atai, Beckley Psytech, other participants in the Acquisition and their respective affiliates or the Acquisition that differ from the views of Guggenheim Securities’ investment banking personnel.

atai does not, as a matter of course, make public projections as to future financial performance, due to, among other reasons, the uncertainty, unpredictability and subjectivity of the underlying assumptions and estimates and the inherent difficulty of predicting financial performance for future periods for a clinical-stage biopharmaceutical company. In connection with the Board’s evaluation of the Acquisition, as described further in the section captioned “The Acquisition—Background of the Acquisition” beginning on page 46 of this proxy statement/prospectus, atai’s management prepared and reviewed with the Board certain unaudited prospective financial information regarding atai’s future operations for the fiscal period second half 2025 (“2H 2025”) and fiscal years 2026 through 2045, as prepared and used as described below (referred to as the “atai Unaudited Prospective Financial Information”). In addition, atai’s management prepared and provided to the Board in connection with its evaluation of the Acquisition, certain nonpublic, internal financial projections regarding Beckley Psytech’s projected future operations from 2H 2025 through 2045 for purposes of evaluating Beckley Psytech and the Acquisition (the “Beckley Psytech Unaudited Prospective Financial Information,” and together with the atai Unaudited Prospective Financial Information, the “Unaudited Prospective Financial Information”).

The Unaudited Prospective Financial Information was prepared for internal use only and not for public disclosure and was provided to the Board for the purposes of considering, analyzing and evaluating the Acquisition. The Unaudited Prospective Financial Information was also provided to, approved by atai for use by, and relied upon by, Guggenheim Securities, atai’s financial advisor, for use in connection with rendering the fairness opinion in connection with the Acquisition and performing its related financial analyses (as described in more detail in the section captioned “The Acquisition—Opinion of Guggenheim Securities” beginning on page 58 of this proxy statement/prospectus), and were the only financial projections with respect to the Company used by Guggenheim Securities in performing such financial analysis. The Unaudited Prospective Financial Information was not provided to Beckley Psytech. The Unaudited Prospective Financial Information includes estimates of atai’s and Beckley Psytech’s financial performance on a risk-adjusted basis. With atai’s consent and at atai’s direction, Guggenheim Securities assumed that the Unaudited Prospective Financial Information was reasonably prepared on bases reflecting the best then-available estimates and judgments of atai management as to its future financial performance and Beckley Psytech’s future financial performance, and relied on atai’s assessments as to the prospects of, and risks associated with, each of atai’s and Beckley Psytech’s product candidates.

The Unaudited Prospective Financial Information was developed based on atai’s management’s knowledge of and assumptions with respect to atai’s and Beckley Psytech’s businesses, including with respect to the development and potential commercialization of each of atai’s and Beckley Psytech’s pipeline drug candidates.

The Unaudited Prospective Financial Information was not prepared with a view toward public disclosure or complying with GAAP. In addition, the Unaudited Prospective Financial Information was not prepared with a view toward complying with the guidelines established by the SEC or the American Institute of Certified Public Accountants with respect to prospective financial information. Neither the Company's independent auditors, nor any other independent accountants, have compiled, examined, or performed any procedures with respect to the prospective financial information contained herein, nor have they expressed any opinion or any other form of assurance on such information or its achievability, and assume no responsibility for, and disclaim any association with, the prospective financial information.

The Unaudited Prospective Financial Information included in this document has been prepared by, and is the responsibility of atai’s management. PricewaterhouseCoopers LLP has not audited, reviewed, examined, compiled nor applied agreed-upon procedures with respect to the accompanying Unaudited Prospective Financial Information and, accordingly, PricewaterhouseCoopers LLP does not express an opinion or any other form of assurance with respect thereto. The PricewaterhouseCoopers LLP report included in this proxy statement/prospectus relates to Beckley Psytech Limited’s previously issued financial statements. It does not extend to the Unaudited Prospective Financial Information and should not be read to do so.

Because the Unaudited Prospective Financial Information reflects estimates and judgments, it is susceptible to sensitivities and assumptions, as well as multiple interpretations based on actual experience and business developments. The Unaudited Prospective Financial Information also covers multiple years, and such information by its nature becomes less predictive with each succeeding year. The Unaudited Prospective Financial Information is not, and should not be considered to be, a guarantee of future operating results. Further, the Unaudited Prospective Financial Information is not fact and should not be relied upon as being necessarily indicative of future results.

Although the Unaudited Prospective Financial Information is presented with numerical specificity, it reflects numerous assumptions and estimates as to future events. The Unaudited Prospective Financial Information will be affected by, among other factors, atai’s and Beckley Psytech’s ability to achieve their respective goals for the development, regulatory approval and commercialization of their product candidates, including on the timelines assumed for purposes of the Unaudited Prospective Financial Information. The Unaudited Prospective Financial Information reflects assumptions and uncertainties that are subject to change. Important factors that may affect actual results and cause the Unaudited Prospective Financial Information not to be achieved are described in various risk factors described in the section entitled “Cautionary Note Regarding Forward-Looking Statements” beginning on page 22 of this proxy statement/prospectus, and in atai’s other filings with the SEC, including those listed under the section entitled “Where You Can Find More Information” beginning on page 213 of this proxy statement/prospectus. All of these factors are difficult to predict, and many of them are outside of atai’s or Beckley Psytech’s control. As a result, there can be no assurance that the Unaudited Prospective Financial Information will be realized, and actual results may be materially better or worse than those contained in the Unaudited Prospective Financial Information, whether or not the Acquisition is consummated. The Unaudited Prospective Financial Information also reflects assumptions as to certain business decisions that are subject to change. The Unaudited Prospective Financial Information may differ from publicized analyst estimates and forecasts and does not consider any events or circumstances after the date that it was prepared, including the announcement of the entry into the Share Purchase Agreement. The Unaudited Prospective Financial Information has not been updated or revised to reflect information or results after the date it was prepared or as of the date of this proxy statement/prospectus. Except to the extent required by applicable federal securities laws, atai does not intend to update or otherwise revise the Unaudited Prospective Financial Information to reflect circumstances existing after the date that such information was prepared or to reflect the occurrence of future events. atai has or may report results of operations for periods included in the Unaudited Prospective Financial Information that were or will be completed following the preparation of the Unaudited Prospective Financial Information. Shareholders and investors are urged to refer to atai’s periodic filings with the SEC for information on atai’s actual historical results.

Certain of the financial measures, such as the unlevered free cash flow, included in the Unaudited Prospective Financial Information are “non-GAAP financial measures.” These are financial performance measures that are not calculated in accordance with GAAP. These non-GAAP financial measures should not be viewed as a substitute for

GAAP financial measures, and may be different from non-GAAP financial measures used by other companies. Furthermore, there are limitations inherent in non-GAAP financial measures because they exclude charges and credits that are required to be included in a GAAP presentation. In certain circumstances, including those applicable to the Unaudited Prospective Financial Information, financial measures included in forecasts provided to a financial advisor and a board of directors in connection with a business combination transaction are excluded from the definition of “non-GAAP financial measures” under applicable SEC rules and regulations. As a result, the Unaudited Prospective Financial Information is not subject to SEC rules regarding disclosures of non-GAAP financial measures, which would otherwise require a reconciliation of a non-GAAP financial measure to a GAAP financial measure. Reconciliations of non-GAAP financial measures were not provided to or relied upon by the Board or Guggenheim Securities. Accordingly, no reconciliation of the financial measures included in the Unaudited Prospective Financial Information is provided in this proxy statement/prospectus.

The Unaudited Prospective Financial Information constitutes forward-looking statements. By including the Unaudited Prospective Financial Information in this proxy statement/prospectus, neither atai nor any of its affiliates, advisors, officers, directors, partners or representatives (including Guggenheim Securities) has made or makes any representation to any person regarding atai’s or Beckley Psytech’s ultimate performance as compared to the information contained in the Unaudited Prospective Financial Information. The inclusion of the Unaudited Prospective Financial Information should not be regarded as an indication that the Board, atai or any other person considered, or now considers, the Unaudited Prospective Financial Information to be predictive of actual future results. Further, the inclusion of the Unaudited Prospective Financial Information in this proxy statement/prospectus does not constitute an admission or representation by atai that the information presented is material. The Unaudited Prospective Financial Information is included in this proxy statement/prospectus solely to give atai’s shareholders access to the information that was provided to the Board and Guggenheim Securities.

Various judgments and assumptions were made when preparing the atai Unaudited Prospective Financial Information, including, among others: costs associated with research and development and selling, general and administrative expenses from 2H 2025 through 2045; treatment of stock based compensation as a cash expense; certain capitalization assumptions; ending cash balances; no financings in 2025; future equity financing transactions and associated cost of equity financings; changes in working capital; timing of peak sales for anticipated product candidates; effective tax rate; utilization of net operating losses; certain royalties assumptions; and other relevant factors relating to atai’s long-term operating plan, as well as future economic, competitive and regulatory conditions and financial market conditions, all of which are highly uncertain, difficult or impossible to predict and many of which are beyond atai’s control.

The following table presents estimates of atai’s total revenue, operating profit and unlevered free cash flow, in each case, on a risk-adjusted basis and from 2H 2025 through 2045, as reflected in the atai Unaudited Prospective Financial Information, as approved by atai management.

Various judgments and assumptions were made when preparing the Beckley Psytech Unaudited Prospective Financial Information, including, among others: a successful BPL-003 Phase 2b trial (results of such Phase 2b trial have now been made available, as previously reported by atai); no value, revenue or costs associated with product candidates being disposed of in connection with the Beckley Carve-Out; revenue associated with BPL-003, including timing for net peak sales, timing of the launch year, loss of exclusivity and certain other assumptions; costs associated with research and development and selling, general and administrative expenses from 2H 2025 through 2045; treatment of stock based compensation as a cash expense; certain capitalization assumptions; ending cash balances; dilutive and non-dilutive equity financing transactions and associated cost of equity financings; changes in working capital; effective tax rate; utilization of net operating losses; and other relevant factors, as well as future economic, competitive and regulatory conditions and financial market conditions, all of which are highly uncertain, difficult or impossible to predict and many of which are beyond atai’s control.

The following table presents estimates of Beckley Psytech’s total revenue, operating profit and unlevered free cash flow, in each case, on a risk-adjusted basis and from 2H 2025 through 2045, as reflected in the Beckley Unaudited Prospective Financial Information, as approved by atai management.