424B3 1 tmb-20260514x424b3.htm 424B3

Filed Pursuant to Rule 424(b)(3)

Registration No. 333-288735

PROSPECTUS SUPPLEMENT No. 3

(To Proxy Statement/Prospectus dated September 26, 2025)

SUPPLEMENT TO

PROSPECTUS FOR UP TO 151,970,541 SHARES OF COMMON STOCK, AND

18,350,000 WARRANTS TO PURCHASE SHARES OF COMMON STOCK

TERRESTRIAL ENERGY INC

This Supplement No. 3 (this “Supplement No. 3”) updates, amends and supplements the definitive proxy statement/prospectus dated September 26, 2025 (as supplemented or amended from time to time, the “Prospectus”), which forms a part the Registration Statement on Form S-4 (Registration No. 333-288735, the “Form S-4”) filed by Terrestrial Energy Inc. (formerly known as HCM II Acquisition Corp., or “HCM II”). Capitalized terms used in this prospectus supplement and not otherwise defined herein have the meanings specified in the Prospectus.

This Supplement No. 3 is being filed to update, amend and supplement the information included in the Prospectus with information contained in our Quarterly Report on Form 10-Q filed with the SEC on May 14, 2026, which is set forth below. To the extent information in this Supplement No. 3 differs from, updates or conflicts with information contained in the Prospectus, the information in this Supplement No. 3 is the more current information. This Supplement No. 3 is not complete without the Prospectus. This Supplement No. 3 should be read in conjunction with the Prospectus, which is to be delivered with this Supplement No. 3, and is qualified by reference thereto, except to the extent that the information in this Supplement No. 3 updates or supersedes the information contained in the Prospectus. Please keep this prospectus supplement with the Prospectus for future reference.

Investing in our securities involves a high degree of risk. See “Risk Factors” beginning on page 12 of the Prospectus.

NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES REGULATORY AGENCY HAS APPROVED OR DISAPPROVED OF THE SECURITIES DESCRIBED IN THE PROSPECTUS OR THIS PROSPECTUS SUPPLEMENT OR PASSED UPON THE ADEQUACY OR ACCURACY OF THE DISCLOSURE IN THE PROSPECTUS OR THIS PROSPECTUS SUPPLEMENT. ANY REPRESENTATION TO THE CONTRARY CONSTITUTES A CRIMINAL OFFENSE.

The date of this prospectus supplement is May 14, 2026.

This Supplement No. 3 should be read in conjunction with the Prospectus, which should be read carefully and in its entirety.

Table of Contents

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

(Mark One)

☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES

EXCHANGE ACT OF 1934

For the quarterly period ended March 31, 2026

☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES

EXCHANGE ACT OF 1934

For the transition period from to

Commission File Number: 001-42252

TERRESTRIAL ENERGY INC.

(Exact name of registrant as specified in its charter)


Delaware	98-1785406
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification Number)

2730 W. Tyvola Road

Suite 100

Charlotte, NC 28217

(Address of Principal Executive Offices)

(646) 687-8212

(Registrant’s telephone number)

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

Title of Each Class	Trading symbol	Name of Exchange on which registered
Common Stock, par value $0.0001 per share	IMSR	The Nasdaq Stock Market LLC
Redeemable Warrants, each whole warrant exercisable for one Common Stock at a price of $11.50 per share	IMSRW	The Nasdaq Stock Market LLC

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.

Large accelerated filer	☐	Accelerated filer	☐

Non-accelerated filer	☒	Smaller reporting company	☒	Emerging growth company	☒

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 is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

As of May 6, 2026, there were 105,935,254 of the registrant’s ordinary shares outstanding.

Table of Contents

TABLE OF CONTENTS


		Page

	Cautionary Note Regarding Forward-Looking Statements

Part I	Financial Information	4

Item 1.	Financial Statements (Unaudited)	4

	Condensed Consolidated Balance Sheets as of March 31, 2026 and December 31, 2025 (Unaudited)	4

	Condensed Consolidated Statements of Operations and Comprehensive Loss for the three months ended March 31, 2026 and 2025 (Unaudited)	5

	Condensed Consolidated Statements of Stockholders’ Equity (Deficit) for the three months ended March 31, 2026 and 2025 (Unaudited)	6

	Condensed Consolidated Statements of Cash Flows for the three months ended March 31, 2026 and 2025 (Unaudited)	7

	Notes to Condensed Consolidated Financial Statements (Unaudited)	8

Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	19

Item 3.	Quantitative and Qualitative Disclosures about Market Risk	23

Item 4.	Controls and Procedures	23

Part II	Other Information	25

Item 1.	Legal Proceedings	25

Item 1A.	Risk Factors	25

Item 2.	Unregistered Sales of Equity Securities and Use of Proceeds	25

Item 3.	Defaults Upon Senior Securities	25

Item 4.	Mine Safety Disclosures	25

Item 5.	Other Information	25

Item 6.	Exhibits	25

Exhibit Index		26

Signatures		27

Table of Contents

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Quarterly Report on Form 10-Q (this “Quarterly Report”) of Terrestrial Energy Inc. (“Terrestrial Energy,” the “Company,” “we,” “our,” and “us”) contains certain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). Forward-looking statements relate to future events or future performance and include, without limitation, statements concerning our business strategy, future revenues, market growth, capital requirements, product introductions, expansion plans and the adequacy of our funding. Other statements contained in this Quarterly Report that are not historical facts are also forward-looking statements. We have tried, wherever possible, to identify forward-looking statements by terminology such as “may,” “will,” “could,” “should,” “expects,” “anticipates,” “intends,” “plans,” “believes,” “seeks,” “estimates,” “continue,” “might,” “possible,” “potential,” “predict,” “project,” “goal,” “would,” “commit,” and other stylistic variants denoting forward-looking statements.

We caution investors that any forward-looking statements presented in this Quarterly Report, or that we may make orally or in writing from time to time, are based on information currently available, as well as our beliefs and assumptions. The actual outcome related to forward-looking statements will be affected by known and unknown risks, trends, uncertainties, and factors that are beyond our control or ability to predict. Although we believe that our assumptions are reasonable, they are not guarantees of future performance, and some will inevitably prove to be incorrect. As a result, our actual future results can be expected to differ from our expectations, and those differences may be material. Accordingly, investors should use caution in relying on forward-looking statements, which are based only on known results and trends at the time they are made, to anticipate future results or trends.

The forward-looking statements contained in this Quarterly Report are based on current expectations and beliefs concerning future developments and their potential effects on us. There can be no assurance that future developments affecting us will be those that we have anticipated. These forward-looking statements involve a number of risks, uncertainties (some of which are beyond our control), or other assumptions that may cause actual results or performance to be materially different from those expressed or implied by these forward-looking statements.

The discussion in this Quarterly Report should be read in conjunction with the condensed consolidated financial statements and notes thereto included in Item 1 of this Quarterly Report. Should one or more of these risks or uncertainties materialize, or should any of our assumptions prove incorrect, actual results may vary in material respects from those projected in these forward-looking statements, whether as a result of new information, future events or otherwise, except as may be required under applicable securities laws.

This Quarterly Report and all subsequent written and oral forward-looking statements attributable to us or any person acting on our behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this section. We do not undertake any obligation to release publicly any revisions to our forward-looking statements to reflect events or circumstances after the date of this Quarterly Report, except as may be required by law.

Table of Contents

PART I —FINANCIAL INFORMATION

Item 1. Financial Statements

Terrestrial Energy Inc.

Condensed Consolidated Balance Sheets

(in thousands, except share data)

(Unaudited)


		March 31,			December 31,
		2026			2025
ASSETS
Current assets
Cash and cash equivalents		$	76,946		$	97,164
Short-term investments			198,018			200,626
Prepaid expenses and other current assets			1,779			1,769
Total current assets			276,743			299,559

Property and equipment, net			831			835
Long-term investments			14,898			—
Intangible assets, net			699			708
Right-of-use assets			1,919			1,814
Other assets			78			64
Total Assets		$	295,168		$	302,980

LIABILITIES AND STOCKHOLDERS’ EQUITY
Current liabilities
Accounts payable and accrued expenses		$	4,495		$	5,501
Operating lease liabilities, current			520			383
Finance lease liabilities, current			33			33
Total current liabilities			5,048			5,917

Operating lease liabilities, noncurrent			1,478			1,601
Finance lease liabilities, noncurrent			46			56
Total liabilities			6,572			7,574

Commitments and Contingencies (Note 10)

Stockholders’ Equity
Common shares, $0.0001 par value; 500,000,000 authorized shares; 82,242,434 and 81,771,422 shares issued and outstanding as of March 31, 2026 and December 31, 2025, respectively			8			8
Exchangeable shares, $0.0001 par value; 23,692,820 and 24,011,017 shares issued and outstanding as of March 31, 2026 and December 31, 2025			2			2
Additional paid-in-capital			421,734			418,815
Accumulated deficit			(135,128)			(124,625)
Accumulated other comprehensive income			1,980			1,206
Total stockholders’ equity			288,596			295,406
Total liabilities and stockholders’ equity		$	295,168		$	302,980

The accompanying notes are an integral part of these condensed consolidated financial statements.

Table of Contents

Terrestrial Energy Inc.

Condensed Consolidated Statements of Operations and Comprehensive Loss

(in thousands, except share data)

(Unaudited)


	Three months ended
	March 31,
	2026		2025

OPERATING EXPENSES
Research and development costs	$	4,566	$	1,408
General and administrative		7,304		3,289
Depreciation and amortization		61		181
Total Operating Expenses		11,931		4,878
OPERATING LOSS		(11,931)		(4,878)

OTHER INCOME (EXPENSE)
Government grants		48		23
Interest expense		(2)		(1,231)
Interest expense – related party		—		(140)
Interest and dividend income		1,453		4
Foreign exchange loss		(34)		(30)
OTHER INCOME (EXPENSE)		1,465		(1,374)

Net loss before income tax		(10,466)		(6,252)
Income tax expense		(37)		—
Net loss		(10,503)		(6,252)

Loss per common share, basic and diluted	$	(0.10)	$	(0.10)
Weighted-Average Shares of Common Shares Outstanding, Basic and diluted		105,861,986		63,170,918

Net loss	$	(10,503)	$	(6,252)
Other comprehensive (loss) income net of tax:
Foreign currency translation adjustments		(64)		(827)
Change in net unrealized gains on short-term and long-term investments		838		—
Comprehensive loss	$	(9,729)	$	(7,079)

The accompanying notes are an integral part of these condensed consolidated financial statements.

Table of Contents

Terrestrial Energy Inc.

Condensed Consolidated Statements of Changes in Stockholders’ Equity (Deficit)

(in thousands, except share data)

(Unaudited)



									Accumulated
							Additional		Other				Total
	Common Shares			Exchangeable Shares			Paid-In-		Comprehensive		Accumulated		Stockholders'
	Shares	Amount		Shares	Amount		Capital		Income		Deficit		Equity
Balance as of January 1, 2026	81,771,422	$	8	24,011,017	$	2	$	418,815	$	1,206	$	(124,625)	$	295,406
Stock-based compensation	—		—	—		—		2,761		—		—		2,761
Shares issued upon exercise of options	140,815		—	—		—		158		—		—		158
Conversion of exchangeable shares to common shares	318,197		—	(318,197)		—		—		—		—		—
Issuance of shares for private placement	12,000		—	—		—		—		—		—		—
Currency translation adjustments	—		—	—		—		—		(64)		—		(64)
Change in unrealized gains on short-term and long-term investments	—		—	—		—		—		838		—		838
Net loss	—		—	—		—		—		—		(10,503)		(10,503)
Balance, March 31, 2026	82,242,434	$	8	23,692,820	$	2	$	421,734	$	1,980	$	(135,128)	$	288,596


									Accumulated
									Other
							Additional		Comprehensive				Total
	Common Shares			Exchangeable Shares			Paid-In-		Income		Accumulated		Stockholders'
	Shares*	Amount		Shares*	Amount		Capital		(Loss)		Deficit		Deficit
Balance as of January 1, 2025, as recast	39,159,901	$	4	24,011,017	$	2	$	82,774	$	337	$	(96,608)	$	(13,491)
Stock-based compensation	—		—	—		—		180		—		—		180
Issuance of warrants in connection with convertible notes, net of tax	—		—	—		—		2,595		—		—		2,595
Currency translation adjustments	—		—	—		—		—		(827)		—		(827)
Net loss	—		—	—		—		—		—		(6,252)		(6,252)
Balance, March 31, 2025	39,159,901	$	4	24,011,017	$	2	$	85,549	$	(490)	$	(102,860)	$	(17,795)

* The shares of the Company’s common stock prior to the Recapitalization have been retrospectively recast to reflect the change in the capital structure as a result of the Recapitalization as described in Note 1.

The accompanying notes are an integral part of these condensed consolidated financial statements.

Table of Contents

Terrestrial Energy Inc.

Condensed Consolidated Statements of Cash Flows

(in thousands)

(Unaudited)


	Three months ended
	March 31,
	2026		2025
Cash flows from operating activities
Net loss	$	(10,503)	$	(6,252)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization		61		181
Amortization of debt discount		—		517
Interest income and accretion of discount on investments, net		(55)		—
Stock-based compensation		2,761		180
Unrealized foreign currency transaction gain		(378)		(96)
Noncash lease expense		99		62
Changes in operating assets and liabilities
Prepaid expenses and other current assets		27		(150)
Accounts payable and accrued expenses		(908)		2,023
Accrued interest		—		663
Accrued interest - related party		—		143
Operating lease payments		(197)		(31)
Net cash used in operating activities		(9,093)		(2,760)

Cash flows from investing activities
Purchases of intangible assets		—		(21)
Purchases of property and equipment		(53)		(163)
Purchase of investments		(73,146)		—
Proceeds from redemptions of investments		61,693		—
Net cash used in investing activities		(11,506)		(184)

Cash flows from financing activities
Proceeds from issuance of convertible notes		—		9,335
Proceeds from issuance of convertible notes – related parties		—		1,650
Proceeds from the exercise of stock options for common shares		158		—
Repayment of finance lease liabilities		(9)		(40)
Net cash provided by financing activities		149		10,945

Effect of exchange rate changes on cash and cash equivalents		232		295

(Decrease) increase in cash and cash equivalents during the period		(20,218)		8,296
Cash and cash equivalents, beginning of period		97,164		3,022
Cash and cash equivalents, end of period	$	76,946	$	11,318

Supplemental noncash investing and financing activities
Recognition of warrants in connection with convertible notes, net of tax	$	—	$	2,595
Operating lease liabilities obtained in exchange for operating lease assets	$	228	$	—

The accompanying notes are an integral part of these condensed consolidated financial statements.

Table of Contents

Terrestrial Energy Inc.

Notes to Condensed Consolidated Financial Statements

(in thousands, except share data or otherwise stated)

(Unaudited)

1. Organization and Description of Business

Terrestrial Energy Inc. (the “Company” or “TEI”), a Company incorporated under the laws of the State of Delaware, is a Company developing Generation IV nuclear technology, as defined by the Generation IV International Forum. The Company is committed to delivering reliable, resilient, emission-free, and cost-competitive energy by developing and deploying its patented Integral Molten Salt Reactor (“IMSR”) for commercial operation.

On October 28, 2025 (the “Closing Date”), Terrestrial Energy Inc. (formerly HCM II Acquisition Corp. “HCM II”) consummated the transactions set forth by the Business Combination Agreement dated March 26, 2025 with Terrestrial Energy Development Inc. (formerly Terrestrial Energy, Inc.) (“TEDI”) and HCM II Merger Sub Inc. (the “Business Combination”). Upon closing, Merger Sub merged with and into TEDI, with TEDI surviving as a wholly owned subsidiary of Terrestrial Energy Inc. (collectively, the “Transactions”). Under the terms of the Agreement, TEDI’s outstanding shares of common stock and convertible notes were exchanged for shares in Terrestrial Energy Inc. at an exchange ratio specified in the Business Combination Agreement.

The Business Combination was accounted for as a reverse recapitalization in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”). Under this method of accounting, TEDI was deemed to be the accounting acquirer for financial reporting purposes.

The Business Combination closed on Tuesday, October 28, 2025, with trading commencing on the Nasdaq Stock Market LLC (“Nasdaq”) on Wednesday, October 29, 2025.

Upon closing of the transaction, the combined company became known as Terrestrial Energy Inc. and its securities and warrants were listed on Nasdaq under the symbols “IMSR” and “IMSRW”, respectively.

Liquidity and Going Concern

Historically, the Company’s primary sources of liquidity have been cash flows from private fundraising offerings to related parties or other investors and other financing activities to fund operations. For the three months ended March 31, 2026 and 2025, the Company reported operating losses of $11,931 and $4,878, respectively, and negative cash flows from operations of $9,093 and $2,760, respectively. As of March 31, 2026, the Company had $76,946 in cash and cash equivalents and $198,018 in short-term investments. The Company had net working capital of $271,695 and an accumulated deficit of $135,128.

The Company believes that it has sufficient liquidity to support operations for at least the next twelve months following the date of issuance of the condensed consolidated financial statements. This projection is based on the Company’s current expectations regarding cost structure, cash burn rate and other operating assumptions.

Table of Contents

Terrestrial Energy Inc.

Notes to Condensed Consolidated Financial Statements

(in thousands, except share data or otherwise stated)

(Unaudited)

2. Significant Accounting Policies

Basis of Presentation and Principles of Consolidation

The accompanying unaudited condensed consolidated financial statements and accompanying notes are prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial reporting.

The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with the instructions to Form 10-Q and Articles 8 and 10 of Regulation S-X of the U.S. Securities and Exchange Commission (“SEC”). Certain information or footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted, pursuant to the rules and regulations of the SEC for interim financial reporting. Accordingly, it does not include all the information and footnotes necessary for a complete presentation of financial position, results of operations, or cash flows. The information herein should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2025, which was filed on March 30, 2026. In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all adjustments, consisting of a normal recurring nature, which are necessary for a fair statement of the financial position, operating results, and cash flows for the periods presented.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make certain estimates, judgments and assumptions. The Company believes that the estimates, judgments and assumptions made when accounting for items and matters such as, but not limited to, determination of deferred income for government assistance, useful life of property and equipment and intangible assets, fair value of stock options granted, recognition of deferred income tax assets, determination of incremental borrowing rate used to measure lease liabilities, and warrants, are reasonable based on information available at the time they are made. These estimates, judgments and assumptions can affect the reported amounts of assets and liabilities as of the date of the condensed consolidated financial statements, as well as amounts reported on the statements of operations during the periods presented. Actual results could differ from those estimates.

Foreign Currency

The Company’s reporting currency is the United States dollar (“USD”). The functional currency of each subsidiary is determined by the currency of the primary economic environment in which the entity operates. The functional currency of Terrestrial Energy Ontario Inc. (“TEON”) is the Canadian dollar (“CAD”), that of Terrestrial Energy Limited, a company incorporated under the laws of England and Wales, the Pound Sterling and that of Terrestrial Energy USA, Inc., the USD. Assets and liabilities of the operating subsidiaries are translated at the spot rate in effect at the applicable reporting date. Revenues and expenses of the operating subsidiaries are translated at the average exchange rates in effect during the applicable period. The resulting foreign currency translation adjustment is recorded as Accumulated other comprehensive income (loss), which is reflected as a separate component of Stockholders’ Equity (Deficit). The functional currency is translated into U.S. dollars for balance sheet accounts using currency exchange rates in effect as of the balance sheet date, and for revenue and expense accounts using a weighted-average exchange rate during the respective reporting period. The transactions in foreign currency (that is a different currency than the functional currency of the entity) are converted at the exchange rate prevailing to the date of the transaction. The assets and liabilities denominated in foreign currencies are evaluated in the current period on the date of the closing or at the opening rate, when applicable. The translation adjustments are deferred as a separate component of equity in “Accumulated other comprehensive income (loss)”. Gains or losses resulting from transactions denominated in foreign currencies and intercompany debt that is not of a long-term investment nature are included in foreign exchange gain (loss) in the condensed consolidated statements of operations and comprehensive loss.

Table of Contents

Terrestrial Energy Inc.

Notes to Condensed Consolidated Financial Statements

(in thousands, except share data or otherwise stated)

(Unaudited)

Concentration of Credit Risks

The Company’s cash accounts in a financial institution may at times exceed the Federal Depository Insurance coverage of $250,000. No losses have been incurred to date on any deposit balance.

Fair Value Measurements

Fair value is defined as the exit price, or the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants as of the measurement date. The authoritative guidance establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the most observable inputs be used when available. Observable inputs are from sources independent of the Company. Unobservable inputs reflect the Company’s assumptions about the factors market participants would use in valuing the asset or liability developed based upon the best information available in the circumstances. The categorization of financial assets and liabilities within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The hierarchy is broken down into three levels:

●

Level 1: Inputs are quoted prices in active markets for identical assets or liabilities.

●

Level 2: Inputs include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, and inputs (other than quoted prices) that are observable for the asset or liability, either directly or indirectly.

●

Level 3: Inputs are unobservable for the asset or liability.

The carrying amounts of certain financial instruments, such as cash equivalents, prepaid expenses and other current assets, accounts payable and accrued expenses, approximate fair value due to their relatively short maturities. The Company’s investments are classified as Level 1 or Level 2 assets (as described in Note 3). The valuation techniques used to measure the fair values of the Company’s Level 2 financial instruments, which generally have counterparties with high credit ratings, are based on quoted market prices or model-driven valuations using significant inputs derived from and corroborated by observable market data.

Warrants

The Company reviews the terms of warrants to purchase its common stock to determine whether warrants should be classified as liabilities or stockholders’ equity (deficit) in its condensed consolidated balance sheets. In order for a warrant to be classified in stockholders’ equity (deficit), the warrant must be (i) indexed to the Company’s equity and (ii) meet the conditions for equity classification.

If a warrant does not meet the conditions for stockholders’ equity (deficit) classification, it is carried on the condensed consolidated balance sheets as a warrant liability measured at fair value, with subsequent changes in the fair value of the warrant recorded in other income (expense) in the condensed consolidated statements of operations and comprehensive loss. If a warrant meets both conditions for equity classification, the warrant is initially recorded, at its relative fair value on the date of issuance, in stockholders’ deficit in the condensed consolidated balance sheets, and the amount initially recorded is not subsequently remeasured at fair value.

Stock-Based Compensation

The Company accounts for stock-based compensation arrangements granted to employees in accordance with Accounting Standards Codification (“ASC”) 718, “Compensation: Stock Compensation”, by measuring the grant date fair value of the award and recognizing the resulting expense over the period during which the employee is required to perform service in

Table of Contents

Terrestrial Energy Inc.

Notes to Condensed Consolidated Financial Statements

(in thousands, except share data or otherwise stated)

(Unaudited)

exchange for the award. Equity-based compensation expense is only recognized for awards subject to performance conditions if it is probable that the performance condition will be achieved. The Company accounts for forfeitures when they occur.

The Company uses the Black-Scholes option pricing model to determine the grant date fair value of its stock-based compensation. This model requires the Company to estimate the expected volatility and the expected term of the stock options, which are highly complex and subjective variables. The Company uses an expected volatility of its stock price during the expected life of the options that is based on the historical performance of the Company’s stock price as well as including an estimate using similar companies. The expected term is computed using the simplified method as the Company’s best estimate given its lack of actual exercise history. The Company has selected a risk-free rate based on the implied yield available on U.S. Treasury securities with a maturity equivalent to the expected exercise term of the stock option.

Prior to the Closing of the Business Combination, there was no public market for the Company’s common stock. Therefore, the Company determined the fair value of common stock at the time of each grant of stock options by considering a number of objective and subjective factors in accordance with applicable elements of the practice aid issued by the American Institute of Certified Public Accountants titled, “Valuation of Privately Held Company Equity Securities Issued as Compensation.” Stock options granted by the Company have exercise prices equal to the fair value of the Company’s common stock, as determined by the Company on the date of grant. After the Closing of the Business Combination, the closing price of the common stock on Nasdaq is used as the fair value of the Company’s common stock.

The Company grants restricted stock units (“RSUs”) to employees and non-employee directors as part of its equity-based compensation program. RSUs represent the right to receive shares of the Company’s common stock upon vesting, subject to specified service. RSUs do not have voting or dividend rights prior to the issuance of shares, except for dividend equivalents if and when declared, as applicable under the terms of the award agreements.

The Company accounts for RSUs in accordance with ASC 718, Compensation—Stock Compensation. Compensation expense for RSUs is measured at the grant-date fair value, which is equal to the closing market price of the Company’s common stock on the date of grant. For RSUs subject solely to service-based vesting conditions, compensation expense is recognized on a straight-line basis over the requisite service period, which is generally the vesting period of the award. The Company accounts for forfeitures as they occur.

Upon vesting, each RSU is converted into one share of the Company’s common stock. The Company may withhold shares to satisfy statutory tax withholding requirements. The issuance of shares upon vesting results in an increase to common stock and additional paid-in capital.

Government Grants

Government grants are recognized where there is reasonable assurance that the grant will be received, and all attached conditions will be complied with. When the grant relates to an expense item, the grant is recognized in other income as government grants deferred over the period necessary to match the grant on a systematic basis to the costs that it is intended to compensate. Where the grant relates to an asset, it is recognized as deferred income, and then recognized as income over the useful life of the related depreciable asset.

Net Loss Per Share

Basic and diluted net loss per share attributable to common stockholders is presented in conformity with the two-class method required for participating securities. The two-class method determines net income (loss) per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income (loss) available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to shares in undistributed

Table of Contents

Terrestrial Energy Inc.

Notes to Condensed Consolidated Financial Statements

(in thousands, except share data or otherwise stated)

(Unaudited)

earnings as if all income (loss) for the period had been distributed. The Company’s preferred stock does not contractually require the holders of such stock to participate in losses of the Company. Accordingly, in periods in which the Company reports a net loss attributable to common stockholders, such losses are not allocated to such participating securities.

Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common stock outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common stock and potentially dilutive securities outstanding for the period. For purposes of this calculation, stock options, warrants, and restricted stock units have been excluded from the calculation of diluted net loss per share attributable to common stockholders as their effect is anti-dilutive for all periods presented.

Segment reporting

The Company has a single operating and reportable segment. The Company’s Chief Executive Officer (“CEO”) is its Chief Operating Decision Maker (“CODM”), who reviews financial information presented on a consolidated basis for the purposes of making operating decisions, allocating resources and evaluating financial performance.

Emerging Growth Company Status

The Company is an emerging growth company, as defined in Section 2(a) of the Securities Act of 1933, as amended, (the “Securities Act”), as modified by the Jumpstart Our Business Startups Act of 2012 (“JOBS Act”). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act, until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that the Company (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opt out of the extended transition period provided in the JOBS Act. As a result, these condensed consolidated financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.

Recent Accounting Pronouncements

The Company has assessed the adoption impacts of recently issued accounting standards by the Financial Accounting Standards Board on the Company’s condensed consolidated financial statements as well as material updates to previous assessments, if any, to the Company’s annual audited consolidated financial statements and notes thereto included in our Form 10-K for the year ended December 31, 2025.

3. Financial Instruments

The following table shows the Company’s cash, cash equivalent and investments by significant investment category as of March 31, 2026:

Table of Contents

Terrestrial Energy Inc.

Notes to Condensed Consolidated Financial Statements

(in thousands, except share data or otherwise stated)

(Unaudited)


	As of March 31, 2026
										Cash and Cash		Short-Term		Long-Term
	Amortized Cost			Unrealized Gains		Unrealized Losses		Fair Value		Equivalents		Investments		Investments
Cash	$	—	$	—	$	—	$	—	$	4,252	$	—	$	—
Level 1:		—		—		—		—		—		—		—
Money market funds		—		—		—		—		72,694		—		—
U.S. Treasury securities		196,039		1,979		—		198,018		—		198,018		—
Level 2:		—		—		—		—		—		—

SEC Form 424B3 filed by Terrestrial Energy Inc.