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. Charlotte, NC 28217 (646) 687-8212 (Address, including zip code, and telephone number, including area code, of registrant's principal executive offices) Simon Irish Chief Executive Officer 2730 W. Tyvola Road, Suite 100 Charlotte, N ...

Financial Performance - The Company had net income of $1,927,839 for the three months ended September 30, 2025, consisting of 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 reported net income of $3,218,865, which includes interest earned of $7,449,387 and 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[151] Marketable Securities and Cash - 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 Company had cash held outside the trust account of $350,389 available for working capital needs[154] - As of September 30, 2025, the fair value of the forward purchase derivative liability was $0[158] Business Combination - The Business Combination Agreement with Terrestrial Energy Inc. was entered into on March 26, 2025, and is expected to close in the fourth quarter of 2025, pending shareholder approvals[138] - The Business Combination Agreement was unanimously approved by the boards of directors of both the Company and Terrestrial Energy[138] - The Company has until August 19, 2026, to complete the initial Business Combination, after which it will face mandatory liquidation if not completed[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] Financing Plans - The Company plans to issue 5,000,000 shares of Domesticated Common Stock at $10.00 per share as part of the PIPE Financing, raising an additional $50,000,000[141] Debt and Obligations - The company has no off-balance sheet arrangements or obligations as of September 30, 2025[159] - There are no long-term debts or capital lease obligations, with a monthly payment of $15,000 to the Sponsor for office space and services[161] 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]

Financial Performance - The company reported a net income of $601,027 for the three months ended June 30, 2025, consisting of interest earned on marketable securities of $2,477,726, offset by operating costs of $1,489,307 and changes in fair value of FPA Liability of $387,392 [139]. - For the six months ended June 30, 2025, the company had a net income of $1,291,026, with interest earned on marketable securities totaling $4,940,590, and operating costs of $2,592,440 [140]. Marketable Securities and Trust Account - As of June 30, 2025, the company held marketable securities in the trust account amounting to $240,134,175, which will be used to complete the Business Combination [148]. - As of June 30, 2025, cash held outside the trust account was $124,083, available for working capital needs [149]. Business Combination - 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, including an over-allotment option [143]. - The company has entered into PIPE Subscription Agreements to issue 5,000,000 shares of Domesticated Common Stock at $10.00 per share, raising additional capital for the Business Combination [137]. - The Business Combination Agreement with Terrestrial Energy Inc. was unanimously approved and is expected to close in Q4 2025, subject to shareholder approvals [134]. - The company has until August 19, 2026, to complete the initial Business Combination, failing which it will trigger an automatic winding up and liquidation [150]. Liabilities and Financial Obligations - The fair value of the Forward Purchase Agreement liability as of June 30, 2025, was $1,057,124, subject to re-measurement at each balance sheet date [154]. - The company has no long-term debt or capital lease obligations, with a monthly payment of $15,000 to the Sponsor for office space and support services [156]. - The underwriter is entitled to a deferred underwriting discount of 4.40% on gross proceeds from the Initial Public Offering, totaling $10,720,000, payable upon completion of the initial Business Combination [157]. Accounting and Reporting - There are no critical accounting estimates disclosed as of June 30, 2025 [158]. - Management believes that recently issued accounting standards will not materially affect the company's financial statements [159]. - The company is classified as a smaller reporting company and is not required to provide additional market risk disclosures [161]. Acquisition Plans - The company expects to incur significant costs in pursuing its acquisition plans and cannot assure the success of completing a business combination [131].

Financial Performance - The Company had a net income of $689,999 for the three months ended March 31, 2025, consisting of interest earned on marketable securities of $2,462,864, offset by operating costs of $1,103,133[136]. - Cash used in operating activities for the three months ended March 31, 2025, was $150,929, with net income affected by interest earned on marketable securities[142]. Marketable Securities - As of March 31, 2025, the Company held marketable securities in the trust account amounting to $237,656,449, which will be used to complete the Business Combination[143]. - The fair value of the forward purchase derivative liability as of March 31, 2025, was $669,732[148]. Initial Public Offering - The Initial Public Offering generated gross proceeds of $230,000,000 from the sale of 23,000,000 Units, including an over-allotment option[139]. - The deferred underwriting discount for the Initial Public Offering is $10,720,000, payable upon the completion of the initial Business Combination[151]. Business Combination - The Business Combination Agreement with Terrestrial Energy is expected to close in the fourth quarter of 2025, pending shareholder approvals[131]. - The Company has until August 19, 2026, to complete the initial Business Combination, after which it will face mandatory liquidation[145]. Company Structure and Compliance - The Company has no long-term debt or off-balance sheet financing arrangements as of March 31, 2025[149]. - Management does not believe that any recently issued accounting standards would have a material effect on the Company's financial statements[153]. - The Company is classified as a smaller reporting company and is not required to provide certain market risk disclosures[155]. Future Financing Plans - The Company plans to issue 5,000,000 shares of Domesticated Common Stock at a price of $10.00 per share as part of the PIPE Financing[134].

IPO and Financial Proceeds - The company completed its Initial Public Offering (IPO) on August 19, 2024, raising gross proceeds of $230,000,000 from the sale of 23,000,000 units at $10.00 per unit[28]. - An additional $6,850,000 was generated from the sale of 6,850,000 Private Placement Warrants at $1.00 each, bringing total gross proceeds to $236,850,000[29]. - A total of $231,150,000 from the net proceeds was placed in a trust account, with an initial value of $10.05 per unit[30]. - Transaction costs related to the IPO amounted to $15,396,014, which included $4,000,000 in underwriting fees and $10,720,000 in deferred underwriting fees[41]. - The company has not generated any revenues to date and expects to incur significant costs in pursuit of its acquisition plans[143][144]. Business Combination Plans - The company must complete a business combination with a fair market value of at least 80% of the assets held in the trust account[42]. - The company anticipates structuring its initial business combination to acquire 100% of the equity interests or assets of the target business, but may also acquire less than 100% under certain conditions[51]. - The company is focused on identifying a target business for a merger or acquisition, with an emphasis on established businesses poised for growth[24]. - The management team emphasizes the importance of quality management in target businesses to ensure efficient scaling and sustained growth[32]. - The company has entered into a Business Combination Agreement with Terrestrial Energy Inc., with the merger expected to close in Q4 2025, subject to shareholder approvals[145][146]. Shareholder Rights and Redemption - The company will provide stockholders the opportunity to redeem shares for a pro rata portion of the trust account, initially valued at $10.05 per share[43]. - Public shareholders will have the opportunity to redeem their shares for cash upon completion of the initial business combination, regardless of their voting decision[82]. - A public stockholder is restricted from seeking redemption rights for more than 10% of the shares sold in the Initial Public Offering, referred to as "Excess Shares"[88]. - Shareholders are restricted from seeking redemption rights for Excess Shares without prior consent, limiting the ability of large shareholders to block the business combination[94]. - The company plans to redeem Public Shares at a per-share price equal to the aggregate amount in the trust account, estimated at approximately $10.05 per share[108]. Financial Management and Risks - The company has not secured third-party financing for its initial business combination, and there is no assurance that such financing will be available[69]. - If the cash consideration required exceeds the available cash, the initial business combination will not be completed, and shares submitted for redemption will be returned[93]. - The company may face significant risks, including the inability to complete its initial business combination and potential dilution of public shareholders' investments[124]. - If the net proceeds from the Initial Public Offering are insufficient, the company may depend on loans from its Sponsor or affiliates to fund its search for a target business[125]. - The company expects to have access to approximately $1,150,000 from the Initial Public Offering proceeds to cover potential claims and liquidation costs[111]. Management and Governance - The company is classified as an "emerging growth company," allowing it to take advantage of certain exemptions from reporting requirements, which may affect the attractiveness of its securities[66]. - The management team has developed a broad network of contacts and corporate relationships, which is expected to provide a substantial number of potential initial business combination targets[58]. - The board of directors consists of five members, with three independent directors, ensuring compliance with Nasdaq rules[190]. - The audit committee is composed solely of independent directors, including Jacob Loveless, ensuring financial oversight and compliance with SEC rules[192]. - The company has adopted a code of ethics applicable to all directors, officers, and employees, ensuring adherence to ethical standards[199]. Operational Status and Future Outlook - The company has not commenced any operations as of December 31, 2024, and will not generate operating revenues until after completing its initial business combination[38]. - The company has until August 19, 2026, to complete the initial Business Combination, or it will face automatic winding up and liquidation[160]. - Management plans to address liquidity concerns through a Business Combination, with substantial doubt raised about the ability to continue as a going concern if not completed[162]. - The company has no off-balance sheet financing arrangements or long-term liabilities, except for a monthly payment of $15,000 to the Sponsor[163][164]. - The company may face adverse effects on its business due to economic uncertainties, including geopolitical instability and inflation[152].

Financial Performance - For the three months ended September 30, 2024, the company reported a net income of $1,071,221, consisting of interest earned on marketable securities of $1,349,715, offset by operating costs of $278,494[90] - From inception on April 4, 2024, through September 30, 2024, the company had a net income of $1,018,558, with total interest earned of $1,349,715 and operating costs of $331,157[90] Marketable Securities and Trust Account - As of September 30, 2024, the company held marketable securities in the trust account amounting to $232,499,715, which will be used primarily to complete a Business Combination[97] - The company plans to use funds held in the Trust Account for working capital to finance operations of the target business post-Business Combination[94] 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 at $10.00 per Unit[93] - The company also sold 6,850,000 Private Placement Warrants at $1.00 per warrant, generating additional gross proceeds of $6,850,000[93] Cash and Operating Activities - Cash held outside the trust account as of September 30, 2024, was $825,134, which is available for working capital needs[98] - The company incurred cash used in operating activities of $294,130 from inception through September 30, 2024[96] Debt and Financing - The company has no long-term debt or off-balance sheet arrangements as of September 30, 2024[101] - The company may need additional financing to complete its Business Combination or to address potential redemptions of Public Shares[100]