SEC Form 424B7 filed by Atai Beckley N.V

This prospectus supplement relates to an aggregate 123,134,069 of our common shares, nominal value €0.10 per share (“common shares”) that are already issued and outstanding and are now being registered to satisfy certain registration rights pursuant to that certain registration rights agreement, dated June 2, 2025 (the “Registration Rights Agreement”) and the related joinder agreements thereto. These common shares may be offered from time to time by the selling securityholders identified in the “selling securityholders” section of this prospectus supplement (the “selling securityholders”). We will not receive proceeds from any such sales and have agreed to pay certain registration expenses.

The registration of 123,134,069 of our common shares relates to (i) 81,266,384 common shares received by certain of the selling securityholders in connection with the Share Purchase Agreement, dated June 2, 2025, among us, Beckley Psytech Limited (“Beckley Psytech”) and certain other parties thereto (as amended by the Side Letter Deed to the Share Purchase Agreement, dated October 23, 2025, the “SPA”), relating to our acquisition of the entire issued share capital of Beckley Psytech not already owned by us, which closed on November 5, 2025 (the “Acquisition”) and (ii) 41,867,685 common shares held by Apeiron Holders (as defined in the Registration Rights Agreement). These common shares are being registered pursuant to the registration rights we respectively granted to such selling securityholders in the Registration Rights Agreement.

The selling securityholders may offer and sell from time to time, together or separately, the common shares described in this prospectus supplement and the accompanying prospectus through one or more underwriters, dealers and agents, or directly to purchasers, or through a combination of these methods. If any underwriters, dealers or agents are involved in the sale of any of the common shares, their names and any applicable purchase price, fee, commission or discount arrangement between or among them will be set forth, or will be calculable from the information set forth, in the applicable prospectus supplement. See the sections of this prospectus supplement entitled “About this Prospectus Supplement,” “Use of Proceeds” and “Plan of Distribution” for more information. No securities may be sold without delivery of this prospectus supplement and the accompanying prospectus describing the method and terms of the offering of such securities.

Our common shares are listed on the Nasdaq Global Market under the symbol “ATAI.” On December 4, 2025, the last reported sale price of our common shares on the Nasdaq Global Market was $4.40 per share.

Investing in our securities involves risks. See the “Risk Factors” on page S-6 of this prospectus supplement, in the similar section contained in the accompanying prospectus and in the documents incorporated by reference in this prospectus supplement concerning factors you should consider before investing in our securities.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus supplement or the accompanying prospectus. Any representation to the contrary is a criminal offense.

This prospectus supplement is part of a registration statement that we have filed with the Securities and Exchange Commission, or SEC, which became automatically effective upon filing, utilizing a “shelf” registration process, and relates to the offering of our common shares. Before buying any of the common shares that the selling securityholders are offering, we urge you to carefully read this prospectus supplement, the accompanying prospectus and all of the information incorporated by reference herein and therein, as well as the additional information described under the heading “Where You Can Find More Information; Incorporation by Reference.” These documents contain important information that you should consider when making your investment decision.

We and the selling securityholders provide information to you about this offering of our common shares in two separate documents that are bound together: (1) this prospectus supplement, which describes the specific details regarding this offering and also adds to and updates information contained in the documents incorporated by reference into this prospectus supplement; and (2) the accompanying prospectus, which provides general information, some of which may not apply to this offering. Generally, when we refer to this “prospectus,” we are referring to both documents combined. If information in this prospectus supplement is inconsistent with the accompanying prospectus, you should rely on this prospectus supplement. To the extent there is a conflict between the information contained in this prospectus supplement, on the one hand, and the information contained in any document incorporated by reference in this prospectus supplement, on the other hand, you should rely on the information in this prospectus supplement. If any statement in one of these documents is inconsistent with a statement in another document having a later date—for example, a document incorporated by reference in this prospectus supplement—the statement in the document having the later date modifies or supersedes the earlier statement.

You should rely only on the information contained in or incorporated by reference in this prospectus supplement, the accompanying prospectus and any free writing prospectus that we may authorize for use in connection with this offering. We have not, and the selling securityholders have not, authorized anyone to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. We are not, and the selling securityholders are not, making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted or in which the person making that offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make an offer or solicitation. You should assume that the information appearing in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference herein and therein and any free writing prospectus that we have authorized for use in connection with this offering, is accurate only as of the date of those respective documents. Our business, financial condition, results of operations and prospects may have changed since those dates. You should read this prospectus supplement, the accompanying prospectus, the documents incorporated by reference herein and therein and any free writing prospectus that we have authorized for use in connection with this offering, in their entirety before making an investment decision.

The distribution of this prospectus supplement and the accompanying prospectus and the offering of the common shares in certain jurisdictions may be restricted by law. Persons outside the United States who come into possession of this prospectus supplement and the accompanying prospectus must inform themselves about, and observe any restrictions relating to, the offering of the common shares and the distribution of this prospectus supplement and the accompanying prospectus outside the United States. This prospectus supplement and the accompanying prospectus do not constitute, and may not be used in connection with, an offer to sell, or a solicitation of an offer to buy, any securities offered by this prospectus supplement and the accompanying prospectus by any person in any jurisdiction in which it is unlawful for such person to make such an offer or solicitation.

We further note that the representations, warranties and covenants made by us or the selling securityholders in any agreement that is filed as an exhibit to any document that is incorporated by reference in this prospectus supplement were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreements, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

When we refer to “AtaiBeckley,” “we,” “our,” “us,” the “Company” and “our company” in this prospectus supplement, we mean Atai Beckley N.V. and its consolidated subsidiaries, unless otherwise specified. When we refer to “you,” we mean the potential holders of the applicable series of securities.

We have proprietary rights to trademarks used in this prospectus supplement that are important to our business, many of which are registered under applicable intellectual property laws. Solely for convenience, trademarks and trade names referred to in this prospectus supplement may appear without the “®” or “™” symbols, but such references are not intended to indicate, in any way, that we will not assert, to the fullest extent possible under applicable law, our rights or the rights of the applicable licensor to these trademarks and trade names. We do not intend our use or display of other companies’ trademarks, trade names or service marks to imply a relationship with, or endorsement or sponsorship of us by, any other companies. Each trademark, trade name or service mark of any other company appearing in this prospectus supplement is the property of its respective holder.

We file reports, proxy statements and other information with the SEC. The SEC maintains a website that contains reports, proxy and information statements and other information about issuers, such as us, who file electronically with the SEC. The address of that website is https://www.sec.gov.

Our website address is https://www.ataibeckley.com. The information contained on, or accessible through, our website does not constitute part of this prospectus supplement. We have included our website address in this prospectus supplement solely as an inactive textual reference.

This prospectus supplement is part of a registration statement that we filed with the SEC and does not contain all of the information in the registration statement. The full registration statement may be obtained from the SEC or us, as provided below. Documents establishing the terms of the offered securities are or may be filed as exhibits to the registration statement or documents incorporated by reference in the registration statement. Statements in this prospectus supplement about these documents are summaries and each statement is qualified in all respects by reference to the document to which it refers. You should refer to the actual documents for a more complete description of the relevant matters. You may inspect a copy of the registration statement through the SEC’s website, as provided above.

The SEC’s rules allow us to “incorporate by reference” information into this prospectus supplement, which means that we can disclose important information to you by referring you to another document filed separately with the SEC. The information incorporated by reference is deemed to be part of this prospectus supplement, and subsequent information that we file with the SEC will automatically update and supersede that information. Any statement contained in this prospectus supplement or a previously filed document incorporated by reference will be deemed to be modified or superseded for purposes of this prospectus supplement to the extent that a statement contained in this prospectus supplement or a subsequently filed document incorporated by reference modifies or replaces that statement.

This prospectus supplement incorporates by reference the documents set forth below that have previously been filed with the SEC, but excluding any information furnished to, rather than filed with, the SEC:

All reports and other documents we subsequently file pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act prior to the termination of this offering but excluding any information furnished to, rather than filed with, the SEC, will also be incorporated by reference into this prospectus supplement and deemed to be part of this prospectus supplement from the date of the filing of such reports and documents.

You may request a free copy of any of the documents incorporated by reference in this prospectus supplement by writing or telephoning us at the following address:

Exhibits to the filings will not be sent, however, unless those exhibits have specifically been incorporated by reference in this prospectus supplement.

Founded in 2025 through the strategic combination of ATAI Life Sciences N.V. and Beckley Psytech Limited, AtaiBeckley is a clinical-stage biopharmaceutical company on a mission to create breakthroughs for people with difficult-to-treat mental health conditions. Our work is grounded in rigorous science to deliver meaningful outcomes for the patients we serve.

Mental health disorders are highly prevalent and estimated to affect more than one billion people globally. The economic burden of these disorders is substantial and is growing rapidly. Between 2009 and 2019, spending on mental health care in the United States increased by more than 50%, reaching $225 billion, and a Lancet Commission report estimates that the global economic cost will reach $16 trillion by 2030. While current treatments, such as selective serotonin reuptake inhibitors and serotonin-norepinephrine reuptake inhibitors are well established and effective for certain patients, approximately 65% of patients do not achieve remission of their symptoms after up to four antidepressant treatment trials, translating to a significant unmet medical need.

The statutory seat of Atai Beckley N.V. is in Amsterdam, the Netherlands. Our office address and our principal executive office is located at Prof. J.H. Bavincklaan 7, 1183 AT Amstelveen, the Netherlands, and our telephone number is +31 20 793 2536. Our website address is https://www.ataibeckley.com. The information contained on, or that can be accessed from, our website does not form part of this prospectus supplement. References to our website address do not constitute incorporation by reference of the information contained on the website, and the information contained on the website is not part of this prospectus supplement or any other document that we file with or furnish to the SEC.

Investment in any securities offered pursuant to this prospectus supplement and the accompanying prospectus involves risks. Before deciding whether to invest in our securities, you should carefully consider the risk factors incorporated by reference to our most recent Annual Report on Form 10-K and any subsequent Quarterly Reports on Form 10-Q or Current Reports on Form 8-K, and all other information contained or incorporated by reference into this prospectus supplement, as updated by our subsequent filings under the Exchange Act, and the risk factors and other information contained in any applicable free writing prospectus. The occurrence of any of these risks might cause you to lose all or part of your investment in the offered securities. There may be other unknown or unpredictable economic, business, competitive, regulatory or other factors that could have material adverse effects on our future results. Past financial performance may not be a reliable indicator of future performance, and historical trends should not be used to anticipate results or trends in future periods. If any of these risks actually occurs, our business, financial condition, results of operations or cash flow could be seriously harmed. This could cause the trading price of our securities to decline, resulting in a loss of all or part of your investment. Please also carefully read the section entitled “Cautionary Note Regarding Forward-Looking Statements” included in our most recent Annual Report on Form 10-K and any subsequent Quarterly Reports on Form 10-Q or Current Reports on Form 8-K. For more information about our SEC filings, please see “Where You Can Find More Information; Incorporation by Reference.”

This prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein and any free writing prospectus that we have authorized for use in connection with this offering contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. 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 of 1933 (as amended, the “Securities Act”) and Section 21E of the Securities Exchange Act of 1934 (as amended, the “Exchange Act”). All statements other than statements of historical facts contained in this prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein and any free writing prospectus are forward-looking statements, including without limitation statements regarding our future operating results and financial position; the success, cost, and timing of development of our product candidates, including the progress of preclinical studies and clinical trials and related milestones; the commercialization of our current product candidates and any other product candidates we may identify and pursue, if approved, including our ability to successfully build a specialty sales force and commercial infrastructure to market our current product candidates and any other product candidates we may identify and pursue; the timing of and our ability to obtain and maintain regulatory approvals; our business strategy and plans, including the benefits of our corporate restructuring and our pending corporate redomiciliation to the U.S.; the Acquisition and potential acquisitions, partnerships and other strategic arrangements; the ability to generate revenue from any current or future licensing agreements and other strategic arrangements, the sufficiency of our cash and cash equivalents and short-term securities to fund our operations; and the plans and objectives of management for future operations and capital expenditures. 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.

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 expressed or implied by the forward-looking statements, including without limitation: we are a clinical-stage biopharmaceutical company and have incurred significant losses since our inception, and we expect to incur losses for the foreseeable future and may never be profitable; if we are unable to obtain funding when needed and on acceptable terms, we could be forced to delay, limit or discontinue our product candidate development efforts; our limited operating history may make it difficult for you to evaluate the success of our business and to assess our future viability; risks related to the Acquisition, including any challenges with integration and expectations regarding the anticipated benefits of the transaction; we rely on third parties to assist in conducting our clinical trials and some aspects of our research and preclinical testing; we currently rely on qualified therapists working at third-party clinical trial sites to administer certain of our product candidates in our clinical trials and we expect this to continue upon approval, if any, of our current or future product candidates, and if third-party sites fail to recruit and retain a sufficient number of therapists or effectively manage their therapists, our business, financial condition and results of operations would be materially harmed; our product candidates are in preclinical or clinical development, which is a lengthy and expensive process with uncertain outcomes, and we cannot give any assurance that any of our product candidates will be successfully developed and/or receive regulatory approval, which is necessary before they can be commercialized; research and development of drugs targeting the central nervous system, or CNS, is particularly difficult, and it can be difficult to predict and understand why a drug has a positive effect on some patients but not others, which may reduce the likelihood our product candidates are ultimately approved and therefore may have a material adverse effect on our business and operating results; the production and sale of our product candidates may be considered illegal or may otherwise be restricted due to the use of controlled substances, which may also have consequences for the legality of investments from foreign jurisdictions and therefore we may not be successful in commercializing our product candidates in such jurisdictions, which will adversely affect our business, financial condition and results of operations; we face significant competition in an environment of rapid technological and scientific change, and there is a possibility that our competitors may achieve regulatory approval before we do or develop therapies that are safer, more advanced or more effective than ours, which may negatively impact our ability to successfully market or commercialize any product candidates we may develop and ultimately harm our financial condition; if we are unable to obtain and maintain sufficient intellectual property protection for our existing product candidates or any other product candidates that we may identify, or if the scope of the intellectual property protection we currently have or obtain in the future is not sufficiently broad, our competitors could develop and commercialize product candidates similar or identical to ours, and our ability to successfully commercialize our

existing product candidates and any other product candidates that we may pursue may be impaired; third parties may claim that we are infringing, misappropriating or otherwise violating their intellectual property rights, the outcome of which would be uncertain and may prevent or delay our development and commercialization efforts; our future success depends on our ability to retain key employees, directors, consultants and advisors and to attract, retain and motivate qualified personnel; if we fail to maintain an effective system of disclosure controls and internal control over financial reporting our ability to produce timely and accurate financial statements or comply with applicable regulations could be impaired; our business is subject to economic, political, regulatory and other risks associated with international operations; a pandemic, epidemic, or outbreak of an infectious disease, such as the COVID-19 pandemic, may materially and adversely affect our business, including our preclinical studies, clinical trials, trial sites, third parties on whom we rely, our supply chain, our ability to raise capital, our ability to conduct regular business and our financial results, and other risks, uncertainties, and assumptions described under “Risk Factors” in Item 1A of Part I, “Management’s Discussion and Analysis of Financial Condition and Results of Operations” in Item 7 of Part II and elsewhere in our Form 10-K for the year ended December 31, 2024, as further updated in “Management’s Discussion and Analysis of Financial Condition and Results of Operations” in Item 2 of our quarterly reports on Form 10-Q for the quarterly periods ended June 30, 2025 and September 30, 2025, in our subsequent filings with the SEC and in this prospectus supplement.

Any forward-looking statements made herein speak only as of the date of this prospectus supplement, 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 prospectus supplement or to conform these statements to actual results or revised expectations.

We will not receive any of the proceeds from the sale of common shares being offered by the selling securityholders, but we have agreed to pay certain registration expenses. To the extent applicable, the selling securityholders will pay any underwriting discounts, selling commissions or transfer taxes incurred by the selling securityholders in connection with the sale of the common shares offered hereby.

The selling securityholders identified in the table below may, from time to time, offer and sell up to 123,134,069 common shares offered by this prospectus supplement and the accompanying prospectus. When we refer to the selling securityholders identified in the table below, we mean the entities identified in the table, and the donees, pledgees, transferees, assignees, designees, distributees or other successors-in-interest who after the date of this prospectus supplement come to hold any of such selling securityholders’ respective interests in our common shares other than through a public sale.

The possible resale from time to time of our common shares by the selling securityholders identified in the table below relates to (i) 81,266,384 common shares received by certain of the selling securityholders in connection with the SPA, relating to the Acquisition and (ii) 41,867,685 common shares held by Apeiron Holders. These common shares are being registered pursuant to the registration rights we respectively granted to such selling securityholders in the Registration Rights Agreement.

The following table sets forth information as of December 1, 2025, regarding the beneficial ownership of our common shares held by the selling security holders identified below, and the number of our common shares that may from time to time be offered or sold by the selling securityholders pursuant to this prospectus supplement. We have prepared the following table based on information given to us by, or on behalf of, the selling securityholders identified below on or before the date hereof with respect to the beneficial ownership of our common shares held by such selling securityholders.

We have not independently verified this information, and this information may change from time to time and any changed information will be set forth in amendments or supplements to this prospectus supplement, if and when necessary. The selling securityholders identified below may offer all, some or none of their common shares, and we cannot advise you as to whether they will in fact sell any or all of such common shares. In addition, the selling securityholders identified below may have sold, transferred or otherwise disposed of, or may sell, transfer or otherwise dispose of, at any time and from time to time, our common shares in transactions exempt from the registration requirements of the Securities Act after the date on which they provided the information set forth in the table below.

The number of common shares beneficially owned by each selling securityholder is determined in accordance with the rules of the SEC, and the information is not necessarily indicative of beneficial ownership for any other purpose. Under such rules, beneficial ownership includes any common shares over which the individual or entity has sole or shared voting power or investment power. Applicable percentage ownership is based on 363,214,602 common shares outstanding as of December 1, 2025. In computing the number of common shares beneficially owned by an individual or entity and the percentage ownership of that person, common shares subject to options, restricted share units or other rights held by such person that are currently exercisable or will become exercisable or will vest within 60 days of December 1, 2025 are considered outstanding, although these common shares are not considered outstanding for purposes of computing the percentage ownership of any other person. Except as otherwise indicated, and subject to applicable community property laws, the persons identified in the table have sole voting and investment power with respect to all common shares held by that person. The information regarding common shares beneficially owned after the offering assumes the sale of all common shares offered by the selling securityholders identified below, and that such selling securityholders do not acquire any additional common shares or additional securities convertible, exchangeable or exercisable into additional common shares. Information in the table below is based on information filed with the SEC or obtained from the persons identified below.

Unless otherwise indicated below, the address for each beneficial owner is Atai Beckley N.V., Prof. J.H. Bavincklaan 7, 1183 AT Amstelveen, the Netherlands.