Amendment: SEC Form 10-K/A filed by ASP Isotopes Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K/A

(Amendment No. 1)

For the year ended December 31, 2025

OR

For the transition period from to

Commission File Number 001-41555

(214) 432-8219

(Registrant’s telephone number, including area code)

Not Applicable

(Former name, former address and former fiscal year, if changed since last report)

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes ☐ No ☒

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes ☐ No ☒

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. ☐

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. ☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b). ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

The aggregate market value of the voting stock held by non-affiliates of the registrant as of June 30, 2025 was approximately $399.8 million.

There were 125,903,447 shares of the registrant’s common stock, $0.01 par value, outstanding as of April 29, 2026.

EXPLANATORY NOTE

ASP Isotopes Inc. (“ASP Isotopes,” the “Company,” “we,” “us,” or “our”) is filing this Amendment No. 1 on Form 10-K/A (this “Amendment”) to amend our Annual Report on Form 10-K for the fiscal year ended December 31, 2025, originally filed with the Securities and Exchange Commission (the “SEC”) on April 10, 2026 (the “Original Filing”), to include the information required by Items 10 through 14 of Part III of Form 10-K. We previously omitted this information from our Original Filing in reliance on General Instruction G(3) to Form 10-K, which permits the information in the above-referenced items to be incorporated in the Original Filing by reference to our definitive proxy statement if such statement is filed no later than 120 days after our fiscal year-end. We are filing this Amendment to provide the information required in Part III of Form 10-K because we will not file a definitive proxy statement containing that information within 120 days after the end of the fiscal year covered by our Original Filing.

ASP Isotopes Inc.

Annual Report on Form 10-K

For the Year Ended December 31, 2025

Table of Contents

PART III

Item 10. Directors, Executive Officers and Corporate Governance

The Board of Directors

Our business affairs are managed under the direction of our board of directors, which is currently comprised of seven members, six of whom are “independent” under the listing standards of the Nasdaq Stock Market LLC (“Nasdaq”). Our board of directors is divided into three classes with staggered three-year terms. At each annual meeting of stockholders, a class of directors is elected for a three-year term to succeed the same class whose term is then expiring.

The following table sets forth the names, ages as of April 29, 2026, and certain other information for each of the directors.

Paul E. Mann co-founded the Company in September 2021 and has served as our Chairman and Chief Executive Officer and a member of our board of directors since incorporation. Paul also served as our Chief Financial Officer until September 2022. Effective January 1, 2026, the Skyline Builders Group Holding Limited board of directors appointed Paul Mann as Executive Chairman. Prior to ASPI, Paul was Chief Financial Officer of PolarityTE, Inc. (Nasdaq: PTE), a biotechnology company, from June 2018 until April 2020. Prior to that, he was responsible for Healthcare investments at DSAM Partners LLC, a global hedge fund. Earlier in his career, he was a portfolio manager at Highbridge Capital where he managed investments in healthcare and biotechnology. Prior to Highbridge Capital, from August 2013 to March 2016, he worked at Soros Fund Management where he was responsible for billions of dollars of investments in healthcare and chemicals companies. During his career as a healthcare and chemicals investor, Paul has helped create and fund numerous early stage and start-up companies. Prior to moving to the buy-side, Paul spent 11 years as a sell-side analyst at Morgan Stanley and Deutsche Bank. He co-managed the healthcare research team at Morgan Stanley, one of the top ranked teams in Institutional Investor, Greenwich and Reuters. He was also corporate broker to over half the UK Pharmaceutical Companies. Paul started his career as a research scientist at Procter and Gamble and he is named as the inventor of numerous skin creams in the Oil of Olay range of cosmetics. Between 2000 and 2023 he was a nonexecutive, independent director at Abeona Therapeutics (NASDAQ: ABEO), where he was the chair of the audit committee. He was the co-founder and Chairman of Varian Biopharma, a private biotechnology company focused on precision oncology until its sale in 2023. Paul has an MA (Cantab) and an MEng from Cambridge University, UK where he studied Natural Sciences and Chemical Engineering and he is a CFA charter holder.

We believe Mr. Mann’s detailed knowledge and unique perspective and insights as our founder and Chief Executive Officer, as well as his prior experience as Chief Financial Officer of another public company and extensive experience managing investments in healthcare, biotechnology and chemicals companies, qualify him to serve on our board of directors and position him well to serve as our Chairman.

Professor Michael Gorley, Ph.D., joined our board of directors in October 2023. Since May 2025, Prof. Gorley has been the Chief Executive Officer of Green Dragon Energy, a consulting company he established with a mission to help drive the green energy transition by empowering fusion, nuclear and green energy research. Prof. Gorley has served as senior fellow since January 2025 at UK Atomic Energy Authority (UKAEA). In this role Prof. Gorley has served as a strategic leader and technical specialist at UKAEA. Prior to assuming his current role at UKAEA, Prof. Gorley was the Director of Fusion Technology Division from January 2024 to January 2025, Chief Technologist from September 2020 till January 2024, Materials Technology Group Leader from August 2018 to September 2020 and Materials Technology Programme Manager from June 2016 to August 2018. In these roles, Prof. Gorley directed the establishment of the Materials Technology Group and supporting Materials Testing Laboratories, and led the EUROfusion Engineering Data and Design Integration group. In addition, Prof. Gorley has been a visiting professor at

the University of Bristol, U.K. since June 2021. Prof. Gorley received a Ph.D. (DPhil) in Materials Science from Oxford University, U.K., with a thesis on ODS steels (specialized alloys for high-performance applications).

We believe that Prof. Gorley’s significant expertise in fusion technology and fusion materials contributes to the Board’s understanding and ability to analyze and navigate complex regulatory and business issues.

Ralph L. Hunter, Jr. joined our board of directors in September 2025. Mr. Hunter has over thirty five years of experience in the nuclear power generation industry. Since June 2025, Mr. Hunter has been the Chairman and Chief Executive Officer of RC Nuclear Consultants, LLC, a consulting company he established to help investors, technology companies, data center developers, power off takers and others navigate the new nuclear landscape. From February 2024 to June 2025, Mr. Hunter was President and Chief Executive Officer of Orion Nuclear Energy Corporation where he led the development company in securing opportunities nationally for both small modular reactors and micro-reactors. From 2013 to February 2024, Mr. Hunter led the development of Constellation Energy Corporation’s international clean energy business in his role as President of Constellation Generation Development, LLC (CGD), and was responsible for all of Constellation's (formerly Exelon Generation) development activities in the nuclear sector worldwide. Mr. Hunter served as Chair on the U.S. Civil Nuclear Trade Advisory Committee (CINTAC) which promoted civil nuclear energy exports, supported marketing U.S. civilian nuclear technologies, innovative U.S. nuclear technologies and the capabilities of U.S. nuclear operators and suppliers. Representing Constellation’s investment in small modular nuclear reactors internationally, Mr. Hunter also served on the Board of Rolls-Royce SMR Limited, a company involved in the United Kingdom’s clean energy development. Mr. Hunter was appointed as a member of the board of directors of Deep Isolation Nuclear, Inc. effective in January 2026. Mr. Hunter holds both a Bachelor of Engineering degree in Nuclear Engineering and a Master of Engineering degree in Nuclear Engineering from the University of Florida. He also attended the Executive Management Program at the Darden School of Business at the University of Virginia and is a certified Project Management Professional.

The Board believes that Mr. Hunter’s extensive relevant experience and competencies, including senior management experience, financial expertise, knowledge of the nuclear energy sector and risk governance, will be a valuable addition to the Board.

Sipho N. Maseko joined our board of directors in April 2025. Mr. Maseko is an experienced executive and serves as a director and advisor to a number of companies. Since March 2024 Mr. Maseko has served as an independent non-executive director of KAP Limited, a South African diversified industrial group consisting of industrial, chemical and logistics businesses, and since June 2023 Mr. Maseko has served as an independent non-executive director of Shoprite Holdings Ltd, Africa’s largest retail group. Mr. Maseko previously served as Chief Executive Officer of Telkom SA SOC Ltd, a South African wireline and wireless telecommunications provider, from April 2013 to June 2022. Prior to joining Telkom, Mr. Maseko served as Managing Director of Vodacom SA and Group Chief Operating Officer of Vodacom after serving almost 14 years at BP Africa Limited where he held a number of senior positions, including Chief Executive Officer and Chief Operating Officer for BP Downstream activities. Mr. Maseko joined BP in 1997 after being with Werksmans Attorneys and the Financial Services Board. Mr. Maseko received a bachelor’s degree from the University of the Witwatersrand and a law degree (LLB) from the University of KwaZulu-Natal.

The Board believes that Mr. Maseko’s extensive relevant experience and competencies, including senior management experience, financial expertise, knowledge of the market and regulatory landscape in South Africa, and risk governance, is a valuable addition to the Board.

Duncan Moore, Ph.D. has served on our board of directors since October 2021. Dr. Moore is a partner at East West Capital Partners since May 2008, which has a focus on making investments in the Healthcare Industry in Asia. Previously, from 1991 to 2008, Dr. Moore was a top-ranked pharmaceutical analyst at Morgan Stanley leading the firm’s global healthcare equity research team. Whilst at the University of Cambridge, he co-founded a medical diagnostics company called Ultra Clone with two colleagues which led to the beginnings of a 20-year career in healthcare capital markets analysis. In 1986, he was involved in setting up the BankInvest biotechnology funds and was on its scientific advisory board. Dr. Moore was educated in Edinburgh and went to the University of Leeds where he studied Biochemistry and Microbiology. He has a M.Phil. and Ph.D. from the University of Cambridge where he was also a post-doctoral research fellow. Dr. Moore is an active investor in biomedical companies and serves as a director of Forward Pharma A/S, a privately held pharmaceutical company based in Copenhagen, Denmark, Cycle Pharma, a privately held rare disease focused company based in Cambridge, UK, and GH Research PLC, a NASDAQ-listed psychedelic pharmaceutical company based in Dublin, Ireland. Dr. Moore is also the Chairman of the Scottish Life Sciences Association.

We believe that the experience, insights and knowledge Dr. Moore possesses from his leadership roles in business activities are important qualifications, skills and experience that provide valuable assistance to the Board and greatly contribute to the overall knowledge of the Board and its ability to address the issues we confront.

Robert Ryan joined our board of directors in January 2024. Mr. Ryan is a private investor with more than 30 years’ experience in investment banking, private equity and international financial law. Mr. Ryan was a partner of Balbec Capital LP from January 2019 to July 2023 and a managing director of Balbec Capital LP from January 2013 to January 2019. Prior to joining Balbec Capital LP, Mr. Ryan was associated with a number of international investment banks. Mr. Ryan started his career as a solicitor at a leading U.K. multinational law firm. Mr. Ryan received a LL.B. degree from the University of Leicester.

The Board believes that Mr. Ryan’s significant board experience and financial expertise contribute to the Board’s understanding and ability to analyze complex issues, particularly as the Company looks to grow its business, and qualify him to serve on our board of directors.

Todd Wider, M.D. has served on our board of directors since October 2021. Dr. Wider is currently Chief Medical Officer and board member of Xanadu Bio, Inc., a company focused on new modes of nanoparticle delivery of therapeutics. In addition, he is Chief Strategy Officer and board member at IsoBio and Chief Medical Officer and board member at Opeongo. Prior, Dr. Wider served as Executive Chairman and Chief Medical Officer of Emendo Biotherapeutics, which focused on highly specific next generation gene editing, until March 2024. Dr. Wider also served on the board of directors of ARYA Sciences Acquisition Corp I, which had a successful business combination with Immatics N.V. (IMTX) in 2020. He served on the board of ARYA Sciences Acquisition Corp II, which had a successful business combination with Nautilus Biotechnology (NAUT) in 2021. He also served on the board of ARYA III, which had a successful business combination with Cerevel Therapeutics (CERE) in 2021. He was also on the boards of ARYA Sciences Acquisition Corp IV (ARYD), which had a successful business combination with Adagio Medical Holdings, Inc. (ADGM) in 2024, and ARYA Sciences Acquisition Corp V (ARYD and ARYE), and Abeona Therapeutics Inc. (Nasdaq: ABEO). Dr. Wider has consulted with a number of entities in the biotechnology space. Dr. Wider is an active, honorary member of the medical staff of Mount Sinai Hospital in New York, where he worked for over 20 years, focused on reconstructive surgery. Dr. Wider received an MD from Columbia College of Physicians and Surgeons, where he was Rudin Fellow, and an AB, with high honors and Phi Beta Kappa, from Princeton University. He did his residency in general surgery and plastic and reconstructive surgery at Columbia Presbyterian Medical Center, and postdoctoral fellowships in complex reconstructive surgery at Memorial Sloan Kettering Cancer Center, where he was Chief Microsurgery Fellow, and in craniofacial surgery at the University of Miami. Dr. Wider is also a principal in Wider Film Projects, a documentary film company focused on producing films with sociopolitical resonance that have won Academy, Emmy and Peabody Awards.

We believe Dr. Wider, as a result of his vast public and private company board experience at a variety of companies, possesses knowledge and experience in various areas, including business leadership, finance and technology, which strengthens the Board’s overall knowledge, capabilities and experience.

Committees of the Board of Directors

Our board of directors has three standing committees: the audit committee, the compensation committee, and the nominating and corporate governance committee, each of which operates pursuant to a charter adopted by our board of directors. Our board of directors may also establish other committees from time to time to assist the board of directors. As of the date of this annual report, the composition and functioning of all of our committees comply with all applicable requirements of the Sarbanes-Oxley Act, Nasdaq, and SEC rules and regulations. Each committee’s charter is available on the Investor Relations portion of our website at https://investors.aspisotopes.com under Governance.

Audit Committee

The members of our audit committee are Robert Ryan, Duncan Moore, and Ralph Hunter, with Mr. Ryan serving as chair. Our board of directors has determined that each member of the audit committee has sufficient knowledge in financial and auditing matters to serve on the audit committee. Our board of directors has designated each of the audit committee members as an “audit committee financial expert,” as defined under the applicable rules of the SEC. Our board of directors has determined that each member of the audit committee meets the independence requirements for audit committees required under Section 10A of the Exchange Act and the applicable Nasdaq rules. The audit committee’s responsibilities include:

Compensation Committee

The members of our compensation committee are Duncan Moore and Robert Ryan, with Dr. Moore serving as chair. Our board of directors has determined that each member of the compensation committee is “independent” as that term is defined in SEC and Nasdaq rules, meets the heightened independence requirements for compensation committee purposes under Section 10C of the Exchange Act and related SEC and Nasdaq rules, and are considered a “non-employee director” under Rule 16b-3 under the Exchange Act. The compensation committee’s responsibilities include:

Nominating and Corporate Governance Committee

The members of our nominating and corporate governance committee are Sipho Maseko, Michael Gorley, and Todd Wider, with Prof. Gorley serving as chair. Our board of directors has determined that each member of the nominating and corporate governance committee is “independent” as defined in Nasdaq rules. The nominating and corporate governance committee’s responsibilities include:

Our Executive Officers

The following table sets forth information regarding our executive officers as of April 29, 2026(1):

Paul E. Mann. Please see the biographical information provided above in the section entitled “Board of Directors.”

Heather Kiessling. Ms. Kiessling has served as our Chief Financial Officer since July 2024. She previously served as Managing Director at Danforth Advisors LLC, a life science financial strategy consultancy and was a consultant since October 2015, providing consulting and advisory services to the Company under the terms of a consulting agreement with Danforth Advisors since November 2021. Prior to joining Danforth Advisors, Ms. Kiessling held finance leadership roles at Cytonome/ST, LLC and AutoImmune Inc. Ms. Kiessling is a CPA and holds a B.A. in management science from University of California, San Diego, and an M.B.A. with a focus in finance and accounting from University of Michigan Graduate School of Business.

Robert Ainscow. Mr. R. Ainscow co-founded the Company in September 2021 and served as our VP and Head of Business Development until September 2022 when he was appointed Interim Chief Financial Officer. Prior to ASP Isotopes, Robert was head of capital markets at Zenzic Partners Limited from October 2017 to February 2021 and a founder of Bluezest Mortgages since November 2015. Robert has over 20 years’ experience in financing operating companies and lending platforms through the provision of structured finance and securitization structures in the debt capital markets. He has developed, executed and managed innovative structures to fund credit, renewable energy and transport and logistics assets encompassing all major financial jurisdictions, on and offshore. Robert began his career at the first ever internet-bank, First-E; in the investment banking division, WIT-Soundview. Following the “.com” correction he entered mainstream investment banking at U.S. firms Morgan Stanley and Bear Stearns in London where he was an analyst in the Law Division with responsibility for capital markets oversight and a Vice President in the Principal and Asset-Backed Finance Group with responsibility for securitization respectively. He subsequently worked at Investec bank twice over the subsequent years as well as a variety of directorships, consultancies and investments in start-up and growth phase lending and securitization platform.

Donald G. Ainscow Mr. D. Ainscow has served as our Executive Vice President, General Counsel and secretary since August 2025. Prior to joining the company, Mr. D. Ainscow was Of Counsel at the law firm Blank Rome LLP from October 2023 to August 2025. During his tenure at Blank Rome, Mr. D. Ainscow worked with ASP Isotopes and QLE as outside counsel on a number of acquisitions, securities and corporate matters. Prior to his time at Blank Rome, Mr. D. Ainscow was Of Counsel at DLA Piper LLP from November 2021 to October 2023. Mr. Ainscow began his legal career in October 2005 at Norton Rose Fulbright US LLP, where he most recently was Senior Counsel from January 2018 to November 2021. Mr. D. Ainscow brings more than 20 years of legal experience to the company’s executive team having worked at several global law firms, where he specialized in corporate law, mergers, acquisitions and other strategic transactions, securities offerings and SEC reporting, financings and corporate governance. Mr. D. Ainscow received a LL.B., with honors, from the University of Warwick, England, and a LL.M. from Duke University School of Law.

Family Relationships

Two members of our management team have a family relationship: Robert Ainscow and Donald G. Ainscow are brothers.

Code of Business Conduct

We have adopted a written code of business conduct that applies to our directors, officers and employees, including our principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions. A copy of the code is posted on the Investor Relations section of our website at www.aspisotopes.com. If we make any substantive amendments to, or grant any waivers from, the code of business conduct and ethics for any officer or director, we will disclose the nature of such amendment or waiver on our website or in a current report on Form 8-K within four business days of such amendment or waiver.

Delinquent Section 16(a) Reports

Section 16(a) of the Exchange Act requires our executive officers, directors and persons who own more than ten percent of a registered class of our equity securities to file reports of ownership and changes in ownership with the SEC. Executive officers, directors and greater than ten-percent shareholders are required by SEC regulation to furnish us with copies of all Section 16(a) forms they file. SEC regulations require us to identify in this report anyone who filed a required report late during the most recent fiscal year.

Based solely on our review of the copies of such forms furnished to us and the written representations from certain of the reporting persons that no other reports were required during the year ended December 31, 2025, all executive officers, directors and greater than ten-percent beneficial owners complied with the reporting requirements of Section 16(a)), except that a late Form 4 report was filed for Dr. Moore on April 17, 2026 (which Form 4 reported two transactions) and a Form 3 and a Form 4 will be filed late for Mr. Maseko due to several failures of the company to obtain EDGAR filer codes on Mr. Maseko’s behalf.

Item 11. Executive Compensation

Processes and Procedures for Compensation Decisions

Our compensation committee is responsible for the executive compensation programs for our executive officers and reports to our board of directors on its discussions, decisions and other actions. Typically, our Chief Executive Officer makes recommendations to our compensation committee, often attends committee meetings and is involved in the determination of compensation for the respective executive officers who report to him, except that the Chief Executive Officer does not make recommendations as to his own compensation. Our Chief Executive Officer makes recommendations to our compensation committee regarding short- and long-term compensation for all executive officers (other than himself) based on our results, an individual executive officer’s contribution toward these results and performance toward individual goal achievement. Our compensation committee then reviews the recommendations and other data and makes decisions as to total compensation for each executive officer, as well as each individual compensation component. Our compensation committee reviews and approves, or makes recommendations for approval by the independent members of the board of directors regarding, the compensation of each executive officer, including our Chief Executive Officer.

Our compensation committee is authorized to retain the services of one or more executive compensation advisors, as it sees fit, in connection with the establishment of our compensation programs and related policies.

Our named executive officers for 2025, which consist of our principal executive officer and our next two most highly compensated executive officers, were as follows:

2025 Summary Compensation Table

The following table sets forth information concerning the compensation awarded to, earned by, or paid to our named executive officers for all services rendered in all capacities to the Company and our subsidiaries for the years ended December 31, 2025 and 2024.

Employment Arrangements with Our Named Executive Officers

Below is a description of our employment agreements with our named executive officers for fiscal year 2025, including a discussion of the severance pay and other benefits to be provided in connection with a termination of employment and/or a change in control under the arrangements with our named executive officers.

Paul Mann

We entered into an executive employment agreement with Mr. Mann in October 2021, which was amended in December 2022 and April 2024, which governs the current terms of his employment with us as Executive Chairman and Chief Executive Officer. Pursuant to the agreement, Mr. Mann is entitled to a base salary of $520,000 per annum (subject to annual adjustments by the board of directors), a target annual discretionary bonus equal to 100% of his annual base salary, and milestone-based bonuses paid in shares of our Common Stock based on the achievement of revenue milestones. Annual bonuses will be paid in a mixture of cash and Common Stock, as determined by the compensation committee.

Subject to our achievement of $4.167 million in average monthly revenues for a trailing three- month period Mr. Mann will be paid a $1,000,000 bonus. Subject to our achievement of $8.33 million in average monthly revenues for a trailing three-month period Mr. Mann will be paid an additional $1,000,000 bonus. Subject to our achievement of $12.5 million in average monthly revenues for a trailing three-month period Mr. Mann will be paid an additional $1,000,000 bonus. Subject to our achievement of $16.67 million in average monthly revenues for a trailing three-month period Mr. Mann will be paid an additional $1,000,000 bonus. Any earned milestone-based bonuses will be paid within 30 days of the achievement of the applicable revenue goal and the number of vested shares issued to Mr. Mann shall be determined by dividing the $1,000,000 bonus amount by either the then fair market value per share of Common Stock, as determined in good faith by our board of directors, or the closing sale price of our Common Stock on the trading day immediately preceding the applicable payment date, as reported by the principal trading market for our Common Stock.

During his employment, Mr. Mann shall receive an equity award equal to two percent (2%) of the Company’s outstanding common shares as of the Company’s immediately preceding fiscal year, which shall be granted on March 1 of each year and vest quarterly over a 12-month period.

Mr. Mann’s employment agreement, as amended, has an initial term of five years ending on April 5, 2029 and will automatically renew for successive one-year periods unless either party provides notice of non-renewal at least three months prior to expiration of the then-current term. Mr. Mann is also entitled to certain severance benefits under the terms of his employment agreement.

Upon a termination of Mr. Mann’s employment for any reason, Mr. Mann is entitled to receive a pro-rata annual bonus for the year of termination.

Upon a termination of Mr. Mann’s employment for any reason other than due to his voluntary resignation without good reason and which does not occur in connection with a change in control, Mr. Mann will receive continued payment of Mr. Mann’s base salary until the end of the then-applicable remaining employment period term and reimbursement of COBRA premiums for up to an 18-month period.

Upon a termination of Mr. Mann’s employment due to his death, disability, termination without cause, resignation for good reason, or resignation in connection with a change of control, the vesting and exercisability of all equity awards held by Mr. Mann shall immediately accelerate, so that all such equity awards shall be fully vested and exercisable as of the date of his termination. Additionally, upon such termination Mr. Mann’s stock options (as well as any other exercisable equity awards) will remain exercisable until the earlier one year after Mr. Mann’ s termination or the original maximum permitted term of the equity award.

Upon a termination of Mr. Mann’s employment for any reason other than due to his voluntary resignation without good reason and which does not occur in connection with a change in control, Mr. Mann will receive continued payment of Mr. Mann’s base salary until the end of the then-applicable remaining employment period term and reimbursement of COBRA premiums for up to an 18-month period.

Heather Kiessling

We entered into an executive employment agreement with Heather Kiessling in June 2024 pursuant to which she was appointed as Chief Financial Officer, effective July 1, 2024. Pursuant to the agreement, Ms. Kiessling is entitled to an initial base salary of $400,000 per annum (subject to annual adjustments by the board of directors) and a target annual discretionary bonus equal to 50% of her annual base salary. Annual bonuses will be paid in a mixture of cash and Common Stock, as determined by the compensation committee. The employment agreement also provides that Ms. Kiessling will be awarded an initial grant of 400,000 shares of restricted stock pursuant to the Company’ 2024 Inducement Equity Incentive Plan, which shall vest (subject to compliance with the applicable vesting conditions) in eight equal semi-annual installments over a four-year period beginning on the six-month anniversary of the Transition Date. The award of 400,000 shares of restricted stock was granted as an inducement material to Ms. Kiessling becoming an employee of the Company, in accordance with Nasdaq Listing Rule 5635(c)(4). Ms. Kiessling will also be eligible to receive annual equity-based awards pursuant to the Company’s 2022 Equity Incentive Plan.

Ms. Kiessling’s employment agreement has an initial term of one year and will automatically renew for successive one-year periods unless either party provides notice of non-renewal at least three months prior to expiration of the then-current term. Ms. Kiessling is also entitled to certain severance benefits under her employment agreement.

Upon a termination of Ms. Kiessling’s employment for any reason other than due to her voluntary resignation without good reason and which does not occur in connection with a change in control, Ms. Kiessling will receive reimbursement of COBRA premiums for up to an 18-month period.

Upon a termination of Ms. Kiessling’s employment due to her death, disability, or termination without cause after the initial one (1)-year term, resignation for good reason, or resignation in connection with a change in control the vesting and exercisability of all equity awards held by Ms. Kiessling shall immediately accelerate, so that all such equity awards shall be fully vested and exercisable as of the date of her termination. Additionally, upon such termination any stock options held by Ms. Kiessling (as well as any other exercisable equity awards) will remain exercisable until the earlier of one year after Ms. Kiessling’s termination or the original maximum permitted term of the equity award.

Robert Ainscow

We entered into an executive employment agreement with Robert Ainscow in October 2021 pursuant to which he was appointed as Vice President and Head of Business Development. We entered into amendments to Mr. R. Ainscow’s employment agreement in September 2022 in connection with his appointment as Interim Chief Financial Officer and in April 2024 in connection with his appointment as Chief Operating Officer and Chief Financial Officer. Pursuant to the agreement (as amended), Mr. R. Ainscow is entitled to a base salary of $360,000 per annum (subject to annual adjustments by the board of directors), a target annual discretionary bonus equal to 40% of his annual base salary, and milestone-based bonuses paid in shares of our Common Stock based on the achievement of revenue milestones. Annual bonuses will be paid in a mixture of cash and Common Stock, as determined by the compensation committee.

Mr. R. Ainscow’s employment agreement, as amended, has an initial term of three years ending on April 5, 2027 and will automatically renew for successive one-year periods unless either party provides notice of non-renewal at least three months prior to expiration of the then-current term. Mr. R. Ainscow is also entitled to certain severance benefits under his employment agreement.

Upon a termination of Mr. R. Ainscow’s employment for any reason other than due to his voluntary resignation without good reason and which does not occur in connection with a change in control, Mr. R. Ainscow will receive reimbursement of COBRA premiums for up to an 18-month period.

Upon a termination of Mr. R. Ainscow’s employment due to his death, disability, or termination without cause, resignation for good reason, or resignation in connection with a change in control the vesting and exercisability of all equity awards held by Mr. R. Ainscow shall immediately accelerate, so that all such equity awards shall be fully vested and exercisable as of the date of his termination. Additionally, upon such termination Mr. R. Ainscow’s stock options (as well as any other exercisable equity awards) will remain exercisable until the earlier of one year after Mr. R. Ainscow’s termination or the original maximum permitted term of the equity award.

Restricted Stock Awards in 2025

On April 14, 2025, we made an award of restricted stock to Mr. Mann pursuant to the terms of his employment agreement. Mr. Mann received 1,441,361 shares of restricted common stock (or 2% of the Company’s outstanding common shares as of the Company’s immediately preceding fiscal year), which will become 25% vested on each of June 1, 2025, September 1, 2025, December 1, 2025 and March 1, 2026.

In addition, on April 14, 2025, we made a discretionary award of restricted stock to Ms. Kiessling and Mr. R. Ainscow. Ms. Kiessling and Mr. R. Ainscow each received 400,000 shares of restricted common stock, which will vest in equal semi-annual installments over a four-year period beginning on the grant date, subject to his or her continuous service with us as of each such vesting date.

QLE Equity Awards

Quantum Leap Energy LLC (QLE) was formed in September 2023 as a wholly owned subsidiary of the Company to focus on the development and commercialization of advanced nuclear fuels, such as High-Assay Low Enriched Uranium (HALEU) and Lithium-6. In 2024, the Quantum Leap Energy LLC 2024 Equity Incentive Plan, as amended (which we refer to as the QLE Equity Plan), was adopted by the QLE board of managers and the board of directors of the Company, and was approved by the Company, as sole member of QLE, and the Company's stockholders at the Company's 2024 annual meeting of stockholders. The maximum aggregate number of shares authorized for issuance under the QLE Equity Plan is 15% of the common equity of QLE deemed outstanding. For purposes hereof, “common equity of QLE deemed outstanding” means: (i) ASP Isotopes Inc.’s shares or equity interest in QLE and (ii) the shares or units of common equity issuable upon conversion of QLE’s convertible promissory notes issued in February and June 2024 (or any securities issued upon conversion or exchange thereof).
 

In 2025, each of our named executive officers (NEOs) received equity awards under the QLE Equity Plan in the form of restricted stock unit (RSU) awards that will vest and become payable only upon consummation of a "Listing Event" (as defined below), which includes certain liquidity events, such as an initial public offering of QLE or a merger of QLE with a SPAC or another public company, subject to the NEO’s continued employment with the Company through the date of such liquidity event. Through this design, our NEOs may only realize liquidity from their QLE equity awards when the Company has achieved liquidity with respect to its ownership stake in QLE and will forfeit their equity awards if their employment terminates for any reason prior to the date of such liquidity event, thereby aligning the NEOs’ incentives with those of the Company and our stockholders.

In 2025, Mr. Mann, Ms. Kiessling, and Mr. R. Ainscow received an RSU award for 2.5%, 1.0%, and 1.0%, respectively, of the common equity of QLE deemed outstanding as of the grant date, each such RSU award subject to vesting in full upon consummation of a "Listing Event". For purposes of the vesting of the RSUs issued to our NEOs, “Listing Event” means the consummation, on or before September 21, 2028, of any of the following transactions by QLE, a corporate successor to QLE or a holding company established with respect to QLE’s equity securities in connection with any of the following transactions (a “Public Issuer”): (i) a listing of common equity of QLE (or the common equity of such Public Issuer) through acquisition by or merger of such Public Issuer with a special purpose acquisition company or another entity listed on the NYSE or NASDAQ, (ii) a firm commitment underwritten public offering pursuant to an effective registration statement under the Securities Act and in connection with such offering the common equity of QLE is listed for trading on the Nasdaq, the NYSE or another exchange or marketplace approved by the Board, or (iii) a direct listing of common equity of QLE (or the common equity securities of the Public Issuer) on the NYSE or Nasdaq.

Health benefits

We provide customary employee benefits to eligible employees, including to our NEOs, including medical, dental and vision benefits, short-term and long-term disability insurance, basic and supplemental life insurance and basic and supplemental accidental death and dismemberment insurance.

Nonqualified deferred compensation

We do not maintain nonqualified defined contribution plans or other nonqualified deferred compensation plans.

Perquisites

We generally do not provide perquisites or personal benefits to our NEOs.

Compensatory Actions After Fiscal Year End

As described above, our named executive officers are eligible to receive annual bonuses in accordance with the terms of their respective employment agreements, with the amount of such bonus and whether such bonus is paid in cash or stock (or a mix of cash and stock) to be determined by the board of directors in its discretion, based on a recommendation of the compensation committee. On April 29, 2026, in recognition of the contributions of Mr. Mann, Ms. Kiessling and Mr. R. Ainscow to the Company in 2025, the board of directors approved, based on a recommendation by the compensation committee, a discretionary cash bonus for 2025 of $600,000, $230,000 and $230,000, respectively. In addition, on April 29, 2026, the Board increased the base salaries of our named executive officers as follows: Mr. Mann $720,000; Ms. Kiessling $550,000; and Mr. R. Ainscow $510,000.

Outstanding Equity Awards at December 31, 2025

The following table sets forth information regarding outstanding option and stock awards held by our named executive officers as of December 31, 2025.

Director Compensation

The following table sets forth information regarding compensation earned by our non-employee-directors for service on our board of directors during the year ended December 31, 2025. The table does not include Mr. Mann, our Executive Chairman and Chief Executive Officer, who did not receive additional compensation for his service as a director.

Effective October 30, 2024, the board of directors adopted a Non-Employee Director Compensation Policy. Under the Non-Employee Director Compensation Policy, our non-employee directors are eligible to receive an annual cash retainer for Board membership of $100,000 (which is prorated for the portion of the year they earned such retainers) and equity awards. Our policy provides that each non-employee director elected to the board will be granted an award of restricted stock with a value of $100,000 (the “Initial Grant”). In addition, on the date of each of our annual meetings of stockholders, each non-employee director who will continue as a non-employee director following such meeting will be granted either an award of restricted stock or an award of nonstatutory stock options, at the election of such director having a value of $250,000 (the “Annual Grant”). The number of shares subject to each of the Initial Grant and Annual Grant is determined by dividing the value of such award by the closing price of our stock over the trailing 30-day period prior to the grant date. The Initial Grant will vest in full on the one-year anniversary of the grant date, subject to continued service as a director. The Annual Grant will vest in full on the earlier of (i) the first anniversary of the grant date or (ii) our next annual meeting of stockholders, subject to continued service as a director through the applicable vesting date.

We will reimburse all reasonable out-of-pocket expenses incurred by directors for their attendance at meetings of our Board or any committee thereof.

Insider Trading Policy

We have adopted an insider trading policy (the “Insider Trading Policy”), governing the purchase, sale and other transactions in our securities that applies to our directors, executive officers, employees, and other covered persons, including immediate family members and entities controlled by any of the foregoing persons, as well as by the Company itself.

The Insider Trading Policy prohibits, among other things, insider trading and certain speculative transactions in our securities (including short sales, buying put and selling call options and other hedging or derivative transactions in our securities) and establishes a regular blackout period schedule during which directors, executive officers, employees, and other covered persons may not trade in our securities, as well as certain pre-clearance procedures that directors and executive officers must observe prior to effecting any transaction in our securities.

We believe that the Insider Trading Policy is reasonably designed to promote compliance with insider trading laws, rules and regulations, and listing standards applicable to us. A copy of the Insider Trading Policy has been filed as an exhibit to the Company’s Annual Report on Form 10-K for the year ended December 31, 2025.

Hedging and Pledging Prohibitions

As part of our Insider Trading Policy, our employees (including our executive officers and the non-employee members of our board of directors) are prohibited from trading in publicly-traded options, such as puts and calls, and other derivative securities with respect to our securities. This includes any hedging or similar transaction designed to decrease the risks associated with holding shares of our common stock.

In addition, our employees (including our executive officers and the non-employee members of our board of directors) are prohibited from holding our common stock in a margin account or pledging our securities as collateral for a loan.

Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

The following table sets forth information relating to the beneficial ownership of our common stock as of April 29, 2026, by:

The number of shares beneficially owned by each entity, person, director or executive officer 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 shares over which the individual has sole or shared voting power or investment power as well as any shares that the individual has the right to acquire within 60 days of April 29, 2026, through the exercise of any stock option, warrants or other rights or vesting of restricted stock units. Except as otherwise indicated, and subject to applicable community property laws, the persons named in the table have sole voting and investment power with respect to all shares of common stock held by that person.

The percentage of shares beneficially owned is computed on the basis of 125,903,447 shares of our common stock outstanding as of April 29, 2026. Shares of our common stock that a person has the right to acquire within 60 days of April 29, 2026, are deemed outstanding for purposes of computing the percentage ownership of the person holding such rights, but are not deemed outstanding for purposes of computing the percentage ownership of any other person, except with respect to the percentage ownership of all directors and executive officers as a group. Unless otherwise indicated below, the address for each beneficial owner listed is c/o ASP Isotopes Inc., 2200 Ross Avenue, Suite 4575E, Dallas, Texas 75201.

* Less than one percent.

Securities Authorized for Issuance under Equity Compensation Plans

The following table gives information as of December 31, 2025, about shares of our common stock that may be issued upon the exercise of options under our existing equity compensation plans:

Item 13. Certain Relationships and Related Transactions and Director Independence

Our common stock is listed on the Nasdaq Stock Market. Under the rules of the Nasdaq Stock Market, independent directors must comprise a majority of a listed company’s board of directors. In addition, the rules of the Nasdaq Stock Market require that, subject to specified exceptions, each member of a listed company’s audit, compensation and nominating and corporate governance committees be independent.

Audit committee members and compensation committee members must also satisfy the independence criteria set forth in Rule 10A-3 and Rule 10C-1, respectively, under the Securities Exchange Act of 1934, as amended (“Exchange Act”). Under the rules of the Nasdaq Global Select Market, a director will only qualify as an “independent director” if, in the opinion of that company’s board of directors, that person does not have a relationship that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director.

To be considered independent for purposes of Rule 10A-3 and under the rules of Nasdaq, a member of an audit committee of a listed company may not, other than in his or her capacity as a member of the audit committee, the board of directors or any other board committee: (1) accept, directly or indirectly, any consulting, advisory or other compensatory fee from the listed company or any of its subsidiaries; or (2) be an affiliated person of the listed company or any of its subsidiaries.

To be considered independent for purposes of Rule 10C-1 and under the rules of Nasdaq, the board of directors must affirmatively determine that each member of the compensation committee is independent, including a consideration of all factors specifically relevant to determining whether the director has a relationship to the company which is material to that director’s ability to be independent from management in connection with the duties of a compensation committee member, including, but not limited to: (i) the source of compensation of such director, including any consulting, advisory or other compensatory fee paid by the company to such director and (ii) whether such director is affiliated with the company, a subsidiary of the company or an affiliate of a subsidiary of the company.

Our board of directors has determined that each of the current non-employee directors, Michael Gorley, Ph.D., Ralph Hunter, Jr., Sipho Maseko, Duncan Moore, Ph.D., Robert Ryan and Todd Wider, M.D., are independent directors. In making this determination, our board of directors applied the standards set forth under applicable SEC and Nasdaq rules. Our board of directors considered all relevant facts and circumstances known to it in evaluating the independence of these directors, including their current and historical employment, any compensation we have given to them, any transactions we have with them, their beneficial ownership of our capital stock, their ability to exert control over us, all other material relationships they have had with us and the same facts with respect to their immediate families.

Although there is no specific policy regarding diversity in identifying director nominees, both the nominating and corporate governance committee and the board of directors seek the talents and backgrounds that would be most helpful to us in selecting director nominees. In particular, the nominating and corporate governance committee, when recommending director candidates to our board of directors for nomination, may consider whether a director candidate, if elected, assists in achieving a mix of board of directors’ members that represents a diversity of background and experience.

Policies and Procedures for Related Party Transactions

Our board of directors has adopted a written related person transaction policy setting forth the policies and procedures for the review and approval or ratification of related person transactions. This policy covers, with certain exceptions set forth in Item 404 of Regulation S-K under the Securities Act, any transaction, arrangement or relationship, or any series of similar transactions, arrangements or relationships in which we were or are to be a participant, where the amount involved exceeds $120,000 and a related person had or will have a direct or indirect material interest, including, without limitation, purchases of goods or services by or from the related person or entities in which the related person has a material interest, indebtedness, guarantees of indebtedness and employment by us of a related person. In reviewing and approving any such transactions, our audit committee is tasked to consider all relevant facts and circumstances, including, but not limited to, whether the transaction is on terms comparable to those that could be obtained in an arm’s length transaction with an unrelated third party and the extent of the related person’s interest in the transaction.

Certain Relationships and Related Transactions

Other than the compensation agreements and other arrangements described in the “Executive Compensation” section of this Annual Report on Form 10-K/A and the transactions described below, since January 1, 2024, there has not been and there is not currently proposed, any transaction or series of similar transactions to which we were, or will be, a party in which the amount involved exceeded, or will exceed, $120,000 and in which any director, executive officer, holder of 5% or more of any class of our capital stock or any member of the immediate family of, or entities affiliated with, any of the foregoing persons, had, or will have, a direct or indirect material interest.

Employment Relationships with Related Persons. Mr. Robert Ainscow, our Chief Operating Officer, is the brother of Donald Ainscow, who was appointed as Executive Vice President, General Counsel and Secretary in August 2025, and Natalie Grancharov was employed by us in March 2026, joining from Intel Corporation as Vice President, Business Development to support the Electronics business. Each of Mr. D. Ainscow’s and Ms. Grancharov’s compensation is greater than $120,000, and consists of a base salary, bonus and equity awards.

Item 14. Principal Accountant Fees and Services

Independent Registered Public Accountants’ Fees

Our audit committee is responsible for the audit fee negotiations associated with the Company’s retention of EisnerAmper LLP ("EisnerAmper") as the independent registered public accounting firm retained to audit the Company’s financial statements. The following table is a summary of fees billed to the Company by EisnerAmper for professional services rendered for the fiscal years ended December 31, 2025 and 2024.

Pre-Approval Policies and Procedures

Our audit committee has established a policy that all audit and permissible non-audit services provided by our independent registered public accounting firm will be pre-approved by the audit committee, and all such services were pre-approved in accordance with this policy during the fiscal years ended December 31, 2025 and 2024. These services may include audit

services, audit-related services, tax services and other services. The audit committee considers whether the provision of each non-audit service is compatible with maintaining the independence of our auditors. Pre-approval is detailed as to the particular service or category of services and is generally subject to a specific budget. Our independent registered public accounting firm and management are required to periodically report to the audit committee regarding the extent of services provided by the independent registered public accounting firm in accordance with this pre-approval, and the fees for the services performed to date.

PART IV

Item 15. Exhibits, Financial Statement Schedules

The following documents are filed as part of this Annual Report on Form 10-K:

The information concerning our consolidated financial statements and Report of Independent Registered Public Accounting Firm required by this Item is incorporated by reference herein to the section of this Annual Report on Form 10-K in Item 8, entitled “Financial Statements and Supplementary Data.”

All schedules have been omitted because the required information is not present or not present in amounts sufficient to require submission of the schedules, or because the information required is included in the Financial Statements or notes thereto.

The list of exhibits filed with this report is set forth in the Exhibit Index immediately preceding the signature page and is incorporated herein by reference.

* Filed herewith.

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized, on the 30th day of April, 2026.