Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2025 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 TERRESTRIAL ENERGY INC. (Exact name of registrant as specified in its charter) 98-1785406 Delaware (Jurisdiction of Incorporation) (I.R.S. Employer Identification No.) 001-4225 ...

Exhibit 99.1 Terrestrial Energy Announces Fourth Quarter and Full Year 2025 Results Texas A&M University selected commercial IMSR plant for deployment at RELLIS campus U.S. Department of Energy selected both Terrestrial Energy reactor pilot and fuel-line pilot projects for advanced reactor programs NRC Accepted IMSR Principal Design Criteria Including Inherent Reactor Control Mechanisms Completed business combination, raising approximately $292 million in gross proceeds CHARLOTTE, N.C. – March 30, 2026 – Te ...

Table of Contents As filed with the U.S. Securities and Exchange Commission on December 22, 2025 Registration No. 333-291796 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 AMENDMENT NO.1 TO FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 TERRESTRIAL ENERGY INC. (Exact name of registrant as specified in its charter) (State or other jurisdiction of incorporation or organization) (Primary Standard Industrial Classification Code Number) 2730 W. Tyvola Road, Suite 100 Ch ...

Table of Contents As filed with the U.S. Securities and Exchange Commission on November 25, 2025 Registration No. 333- UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 TERRESTRIAL ENERGY INC. (Exact name of registrant as specified in its charter) Delaware 3443 98-1785406 (Primary Standard Industrial (I.R.S. Employer Identification Number) Charlotte, NC 28217 (646) 687-8212 (Address, including zip code, and telephone numb ...

Financial Performance - The Company reported a net income of $1,927,839 for the three months ended September 30, 2025, primarily from interest earned on marketable securities of $2,508,797, offset by operating costs of $1,638,082[143]. - For the nine months ended September 30, 2025, the Company had a net income of $3,218,865, with interest income of $7,449,387 and total operating costs of $4,230,522[144]. - The Company incurred cash used in operating activities of $1,055,702 for the nine months ended September 30, 2025, influenced by changes in operating assets and liabilities[151]. Marketable Securities and Trust Account - As of September 30, 2025, the Company held marketable securities in the trust account amounting to $242,642,972, which will be used to complete the Business Combination[153]. - As of September 30, 2025, the fair value of the forward purchase derivative liability was $0[158]. - The company has no off-balance sheet arrangements or obligations as of September 30, 2025[159]. Business Combination - The Business Combination Agreement with Terrestrial Energy Inc. was entered into on March 26, 2025, with an aggregate consideration of $925,000,000 for the merger[137]. - The Business Combination is expected to close in the fourth quarter of 2025, pending shareholder approvals and customary closing conditions[138]. - The Company has until August 19, 2026, to complete the initial Business Combination, or it will trigger an automatic winding up and liquidation[155]. Initial Public Offering - The Company completed its Initial Public Offering on August 19, 2024, raising gross proceeds of $230,000,000 from the sale of 23,000,000 Units[148]. - The underwriter is entitled to a deferred underwriting discount of 4.40% of gross proceeds from the Initial Public Offering, totaling $10,720,000, payable upon completion of the initial Business Combination[162]. Capital and Financing - The Company plans to issue 5,000,000 shares of Domesticated Common Stock at $10.00 per share through PIPE Financing, raising an additional $50,000,000[141]. - As of September 30, 2025, the Company had cash held outside the trust account of $350,389 available for working capital needs[154]. Accounting and Reporting - Management does not have any critical accounting estimates to disclose as of September 30, 2025[163]. - Recent accounting standards are not expected to materially affect the company's financial statements[164]. - The company is classified as a smaller reporting company and is not required to provide additional market risk disclosures[166]. Liabilities - The company has no long-term debt or significant liabilities, except for a monthly payment of $15,000 to the Sponsor for office-related services[161].

Core Points - HCM II Acquisition Corp. has received shareholder approval for its business combination with Terrestrial Energy Inc., a developer of small modular Generation IV nuclear plants utilizing proprietary Integral Molten Salt Reactor (IMSR) technology [1][2] - The closing of the business combination is anticipated on or about October 27, 2025, with trading on Nasdaq commencing on October 28, 2025, under the symbols "IMSR" and "IMSRW" [2] Company Overview - Terrestrial Energy focuses on developing Generation IV nuclear plants that leverage IMSR technology, which offers benefits in capital efficiency, cost reduction, and versatility for various industrial applications [3] - The IMSR plants are designed to provide low-cost, reliable, and clean energy, extending the application of nuclear energy beyond traditional electric power markets [3] - The company aims to support energy demand growth and decarbonization efforts, with plans to license and commission the first IMSR plants for operation in the early 2030s [3] HCM II Acquisition Corp. Overview - HCM II is a special-purpose acquisition company (SPAC) formed to pursue business combinations with established companies poised for growth [4] - The management team includes Shawn Matthews as Chairman and CEO, and Steven Bischoff as President and CFO [5]

Core Viewpoint - HCM II Acquisition Corp. (NASDAQ: HOND) is initiating coverage with a Buy rating, focusing on the public listing of Terrestrial Energy, which is developing an integral molten salt reactor (IMSR) [1] Company Overview - HCM II Acquisition Corp. is facilitating the public listing of Terrestrial Energy, a company engaged in innovative energy solutions [1] Technology Development - Terrestrial Energy is working on the IMSR, which represents a significant advancement in nuclear reactor technology, potentially offering safer and more efficient energy production [1]

Core Insights - Terrestrial Energy Inc. has been selected for the U.S. Department of Energy's Fuel Line Pilot Program, validating its Integral Molten Salt Reactor (IMSR) technology and commercialization strategy [1][3][5] - The Fuel Line Pilot Program aims to address the domestic nuclear fuel resource shortage and enhance the U.S. nuclear fuel supply chain [2][4] - This selection complements Terrestrial Energy's recent participation in the Advanced Reactor Pilot Program, positioning the company at the forefront of the nuclear renaissance in the U.S. [3][5] Company Strategy - Terrestrial Energy's strategy includes establishing an IMSR fuel line within a DOE-authorized facility, linking research and demonstration of IMSR fuel salt production to commercial licensing [2][4] - The company utilizes Standard Assay Low-Enriched Uranium (SALEU) fuel, which is less than 5% uranium-235, to avoid supply challenges associated with High-Assay Low-Enriched Uranium (HALEU) [4][5] - The collaboration with key suppliers like Westinghouse Electric Company will support fuel supply and logistics for the IMSR project [5] Technology and Market Position - IMSR plants are designed to deliver zero-carbon, reliable, and dispatchable power, with a nameplate capacity of 822 MWth / 390 MWe, suitable for various applications including data centers and industrial heat [6][7] - The modular design of IMSR plants allows for distributed energy supply, extending nuclear energy's application beyond traditional electricity markets [7][8] - Terrestrial Energy's focus on innovative reactor technology and a comprehensive fuel cycle strategy positions it to meet the growing demand for reliable, carbon-free power across multiple sectors [5][8]

Core Insights - Terrestrial Energy has achieved a significant milestone with the U.S. Nuclear Regulatory Commission (NRC) issuing its first Safety Evaluation on the Principal Design Criteria (PDC) for the Integral Molten Salt Reactor (IMSR), marking a pivotal step in the commercialization of molten salt reactor technology [1][6] - The NRC's ruling confirms the IMSR's unique safety mechanisms, particularly its use of temperature as an inherent control mechanism for reactor power, enhancing the safety and efficiency of the licensing process [1][2][5] Company Overview - Terrestrial Energy is focused on developing Generation IV nuclear power plants utilizing its proprietary IMSR technology, which aims to provide a cost-effective, versatile, and reliable source of zero-carbon energy [7][8] - The IMSR is designed to be small and modular, suitable for distributed energy supply across various industrial applications, thereby extending the use of nuclear energy beyond traditional electric power markets [8] Regulatory Progress - The NRC's Safety Evaluation serves as a foundational approval for future operating license applications, establishing a design framework that supports the commercialization of the IMSR [6] - In April 2023, the Canadian Nuclear Safety Commission (CNSC) completed a Vendor Design Review (VDR) of the IMSR, concluding that there are no fundamental barriers to licensing the plant for commercial use, further bolstering confidence in the technology [6] Market Potential - The IMSR technology is positioned to contribute significantly to global decarbonization efforts, providing low-cost, dispatchable energy that can support various industrial processes [8] - The successful regulatory approvals and the innovative design of the IMSR highlight its compelling commercial potential in the evolving energy landscape [5][8]

Core Insights - Terrestrial Energy is advancing the commercialization of its Integral Molten Salt Reactor (IMSR) technology to provide high-temperature, clean, and flexible energy solutions for various sectors, including industrial, data centers, and grid power [1] - The company has opened a new corporate headquarters in Charlotte, North Carolina, marking a significant milestone in its growth and commitment to U.S. nuclear supply chains [2][5] - Terrestrial Energy's strategy includes a domestically-secured supply chain and the use of Standard-Assay Low Enriched Uranium (LEU) fuels, distinguishing it from competitors relying on High-Assay Low-Enriched Uranium (HALEU) [4] Company Developments - The new headquarters will facilitate the development of IMSR plants and strengthen the company's leadership in the U.S. advanced nuclear reactor sector [5] - Terrestrial Energy is collaborating with Siemens for sourcing key electric power components, which enhances its supply chain capabilities [4] - The company has achieved a critical materials testing milestone in partnership with NRG PALLAS and signed a memorandum of understanding with Ameresco, Inc. to develop hybrid energy systems [5] Market Positioning - Terrestrial Energy's focus on a U.S.-anchored supply chain mitigates trade uncertainties and reduces reliance on foreign suppliers, positioning the company to leverage America's nuclear ecosystem [3] - The IMSR technology is designed for distributed supply of zero-carbon, reliable, and low-cost energy, extending nuclear energy applications beyond traditional electric power markets [6] - The company aims to build, license, and commission its first IMSR plants in the early 2030s, indicating a long-term growth strategy in the nuclear energy sector [6]