Terrestrial Energy (HONDU) adds UHY LLP consent to S-1 amendment

Rhea-AI Filing Summary

Terrestrial Energy Inc. filed a Post-Effective Amendment No. 1 to its Form S-1 to furnish a consent from UHY LLP relating to the audited financial statements for the years ended December 31, 2025 and December 31, 2024.

The amendment is exhibit-only and states the Registration Statement was initially declared effective on December 23, 2025; the Consent and signature pages are being filed as of March 30, 2026.

Key Figures

Registration No.: 333-291796 Amendment filing date: March 30, 2026 Registration effective date: December 23, 2025 +3 more

6 metrics

Registration No. 333-291796 Registration statement identifier

Amendment filing date March 30, 2026 Post-Effective Amendment No.1 filing date

Registration effective date December 23, 2025 Date the original Registration Statement was declared effective

Audited fiscal years Years ended December 31, 2025 and December 31, 2024 Financial statements covered by UHY LLP consent

I.R.S. Employer ID 98-1785406 Registrant's EIN as listed on cover

Prospectus supplement cited Prospectus Supplement No. 1 dated March 30, 2026 Supplement filing referenced in amendment

Key Terms

Post-Effective Amendment No. 1, Consent of UHY LLP, Prospectus Supplement No. 1

3 terms

Post-Effective Amendment No. 1 regulatory

"This Post-Effective Amendment No. 1 (this “Amendment”) to the Registration Statement"

Consent of UHY LLP regulatory

"to file a consent of UHY LLP with respect to its report dated March 30, 2026"

Prospectus Supplement No. 1 regulatory

"included in the Prospectus Supplement No. 1 dated March 30, 2026 filed pursuant to Rule 424(b)(3)"

Offering Details

other

Offering

Offering Type other

As filed with the U.S. Securities and Exchange Commission on March 30, 2026

Registration No. 333-291796

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

POST-EFFECTIVE 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)

Delaware	​ ​ ​	3443	​ ​ ​	98-1785406
(State or other jurisdiction of incorporation or organization)		(Primary Standard Industrial Classification Code Number)		(I.R.S. Employer Identification Number)

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2730 W. Tyvola Road, Suite 100

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, NC 28217

(646) 687-8212

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Sean Jones

Coleman Wombwell

K&L Gates LLP

300 South Tryon Street

Suite 1000

Charlotte, NC 28202

(704) 331-7406

Approximate date of commencement of proposed sale to the public: From time to time after this registration statement becomes effective.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933 check the following box: ☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering: ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering: ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering: ☒ 333-291796

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:

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Large accelerated filer	☐	Accelerated filer	☐
Non-accelerated filer	☒	Smaller reporting company	☒
		Emerging growth company	☒

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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 7(a)(2)(B) of the Securities Act: ☐

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This Post-Effective Amendment No. 1 to the Registration Statement Shall become effective immediately upon filing with the Securities and Exchange Commission in accordance with Rule 462(d) under the Securities Act.

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EXPLANATORY NOTE

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This Post-Effective Amendment No. 1 (this “Amendment”) to the Registration Statement on Form S-1 of Terrestrial Energy Inc. (File No. 333-291796), initially filed on November 26, 2025, and declared effective by the Securities and Exchange Commission on December 23, 2025 (the “Registration Statement”), is being filed as an exhibit-only filing solely to file a consent of UHY LLP with respect to its report dated March 30, 2026 relating to the financial statements of Terrestrial Energy Inc. for the years ended December 31, 2025 and December 31, 2024 contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025 and included in the Prospectus Supplement No. 1 dated March 30, 2026 filed pursuant to Rule 424(b)(3), filed herewith as Exhibit 23.1 (the “Consent”). Accordingly, this Amendment consists only of the facing page, this explanatory note, Item 16 of Part II of the Registration Statement, the signature pages to the Registration Statement, and the Consent. The prospectus and the balance of Part II of the Registration Statement are unchanged hereby and have been omitted.

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Part II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 16. Exhibits and Financial Statement Schedules.

(a) Exhibits.

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Number	​ ​ ​	Description	​ ​ ​	Form	​ ​ ​	Exhibit	​ ​ ​	Date Filed with the SEC	​ ​ ​	File Number
23.1	*	Consent of UHY LLP	​	​	​	​	​	​	​	​

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* Filed herewith

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SIGNATURES

Pursuant to the requirements of the U.S. Securities Act of 1933, as amended, the registrant has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Charlotte, State of North Carolina, on March 30, 2026.

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TERRESTRIAL ENERGY INC.		​
By:	/s/ Simon Irish	​
Name:	Simon Irish	​
Title:	Chief Executive Officer	​

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Pursuant to the requirements of the Securities Act, this registration statement has been signed by the following persons in the capacities and on the dates indicated below.

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​	​	​	​	​
Signature	​ ​ ​	Title	​ ​ ​	Date
​	​	​	​	​
/s/ Simon Irish	​	Chief Executive Officer and Director	​	March 30, 2026
Simon Irish	​	(Principal Executive Officer)	​	​
​	​	​	​	​
/s/ Brian Thrasher	​	Chief Financial Officer	​	March 30, 2026
Brian Thrasher	​	(Principal Financial and Accounting Officer)	​	​
​	​	​	​	​
*	​	Chairman of the Board of Directors	​	March 30, 2026
Frederick Buckman	​	​	​	​
​	​	​	​	​
*	​	Director	​	March 30, 2026
Shawn Matthews	​	​	​	​
​	​	​	​	​
*	​	Director	​	March 30, 2026
Hugh MacDiarmid	​	​	​	​
​	​	​	​	​
*	​	Director	​	March 30, 2026
David Hill	​	​	​	​
​	​	​	​	​
*	​	Director	​	March 30 2026
Charles Pardee	​	​	​	​
​	​	​	​	​
*	​	Director	​	March 30, 2026
Robert W. Jones	​	​	​	​
​	​	​	​	​
*	​	Director	​	March 30, 2026
William Johnson	​	​	​	​
​	​	​	​	​
*	​	Chief Technology Officer and Director	​	March 30, 2026
David LeBlanc	​	​	​	​

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By:	/s/ Simon Irish
Name:	Simon Irish
	Attorney-in-fact

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FAQ

What did Terrestrial Energy Inc.'s March 30, 2026 S-1 amendment do?

It filed an exhibit-only Post-Effective Amendment to add an auditor consent. The filing supplies UHY LLP's consent for the audited financial statements for years ended December 31, 2025 and December 31, 2024, and includes signature pages.

Does the amendment change the prospectus terms or offering size for HONDU?

No material offering terms were changed in this amendment. The submission is described as exhibit-only; it omits the prospectus text and states the prospectus and remainder of Part II are unchanged.

Which financial periods do the auditor's consent cover in the amendment?

The consent covers audited financial statements for the years ended December 31, 2025 and December 31, 2024. The consent from UHY LLP is included as Exhibit 23.1 to the amendment.

When did the original Registration Statement for Terrestrial Energy become effective?

The Registration Statement was declared effective on December 23, 2025. The amendment notes the initial filing date of November 26, 2025 and the effective date of December 23, 2025.