0001447028-26-000017 | 10-K | XBRL Viewer

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Income taxes - Income Tax Rate Reconciliation, Prior Period (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Income Tax Disclosure [Abstract]
Computed taxes (benefits) at Canadian federal and provincial tax rates	$ (8,374)	$ (18,888)
Permanent and other differences		515
Federal R&D credit		1,122
Change in valuation allowance		11,748
Difference due to income taxed at foreign rates		4,101
Stock-based compensation	304	1,327
Other		2,319
Income tax expense	$ 0	$ 0

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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+ Details

Fair value measurements - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair value of contingent consideration (in $000s)	$ 8,395	$ 10,225	$ 7,600
Increase in fair value of contingent consideration	$ (1,830)	$ 2,625

Significant accounting policies

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Significant accounting policies

Basis of presentation and principles of consolidation

These consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and include the accounts of Arbutus Biopharma Corporation and its one wholly-owned subsidiary, Arbutus Biopharma, Inc. All intercompany balances and transactions have been eliminated.

Use of estimates

The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions about future events that affect the reported amounts of assets, liabilities, revenue, expenses and contingent liabilities as of the end or during the reporting period. Actual results could significantly differ from those estimates. Significant estimates in the accompanying consolidated financial statements impact contingent consideration.

Cash and cash equivalents

Cash and cash equivalents are all highly liquid instruments with an original maturity of three months or less when purchased. Cash equivalents are recorded at cost plus accrued interest. The carrying value of these cash equivalents approximates their fair value.

Investments in marketable securities

The Company’s short-term investments consist of marketable securities that have original maturities exceeding three months and remaining maturities of less than one year. The Company classifies investments with remaining maturities of one year or longer as non-current. These investments are accounted for as available-for-sale securities and are reported at fair value, with unrealized gains and losses reported in other comprehensive loss until their disposition. Realized gains and losses from the sale of marketable securities, if any, are calculated using the specific-identification method, and are recorded as a component of other income or loss. The Company reviews its available-for-sale securities at each period end to determine if they remain available-for-sale based on the Company’s current intent and ability to sell the security if it is required to do so. Declines in value judged to be other-than-temporary are included in interest expense in the Company’s statements of operations and comprehensive loss. As of December 31, 2025, the recorded value of the Company’s investments in marketable securities was deemed to be recoverable in all respects.

All investments are governed by the Company’s Investment Policy approved by the Company’s Board of Directors (the Board).

Foreign currency translation and functional currency conversion

The Company’s functional currency is the United States dollar. Monetary assets and liabilities denominated in foreign currencies are translated into United States dollars using exchange rates in effect at the balance sheet date. Opening balances related to non-monetary assets and liabilities are based on prior period translated amounts, and non-monetary assets and non-monetary liabilities are translated at the approximate exchange rate prevailing at the date of the transaction. Revenue and expense transactions are translated at the approximate exchange rate in effect at the time of the transaction. Foreign exchange gains and losses are included in the statement of operations and comprehensive loss as foreign exchange gains or losses.

Investment in Genevant

Arbutus accounts for its interest in Genevant as equity securities without readily determinable fair values. Accordingly, an estimate of the fair value of the securities is based on the original cost less previously recognized equity method losses, less impairments, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar Genevant securities. As of December 31, 2025, Arbutus owned approximately 16% of the outstanding common equity of Genevant and the carrying value of Arbutus’ investment in Genevant was zero.

See Note 5 for more information.

Property and equipment

Property and equipment is recorded at cost less impairment losses and accumulated depreciation. The Company records depreciation using the straight-line method over the estimated useful lives of the capital assets as follows:


	Useful Life (Years)
Laboratory equipment		5
Computer and office equipment	2	to	5
Furniture and fixtures		5

Leasehold improvements are depreciated over their estimated useful lives but in no case longer than the lease term, except where lease renewal is reasonably assured.

Property and equipment is reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. If such a review should indicate that the carrying amount of long-lived assets is not recoverable, then such assets are written down to their fair values.

Substantially all of the Company’s premises, property and equipment are located in the United States.

See Note 7 for more information.

Revenue from collaborations and licenses

The Company generates revenue through certain collaboration agreements and license agreements. Such agreements may require the Company to deliver various rights and/or services, including intellectual property rights or licenses and research and development services. Under such agreements, the Company is generally eligible to receive non-refundable upfront payments, funding for research and development services, milestone payments and royalties.

The Company’s collaboration agreements fall under the scope of Accounting Standards Codification (ASC) Topic 808, Collaborative Arrangements (ASC 808), when both parties are active participants in the arrangement and are exposed to significant risks and rewards. For certain arrangements under the scope of ASC 808, the Company analogizes to ASC Topic 606, Revenue from Contracts with Customers (ASC 606), for some aspects, including for the delivery of a good or service (i.e., a unit of account).

ASC 606 requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers under a five-step model: (i) identify contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when or as a performance obligation is satisfied.

In contracts where the Company has more than one performance obligation to provide its customer with goods or services, each performance obligation is evaluated to determine whether it is distinct based on whether (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available and (ii) the good or service is separately identifiable from other promises in the contract. The consideration under the contract is then allocated between the distinct performance obligations based on their respective relative stand-alone selling prices. The estimated stand-alone selling price of each deliverable reflects the Company’s best estimate of what the selling price would be if the deliverable was regularly sold on a stand-alone basis and is determined by reference to market rates for the good or service when sold to others or by using an adjusted market assessment approach if the selling price on a stand-alone basis is not available.

The consideration allocated to each distinct performance obligation is recognized as revenue when control is transferred to the customer for the related goods or services. Consideration associated with at-risk substantive performance milestones, including sales-based milestones, is recognized as revenue when it is probable that a significant reversal of the cumulative revenue recognized will not occur. Sales-based royalties received in connection with licenses of intellectual property are subject to a

specific exception in the revenue standards, whereby the consideration is not included in the transaction price and recognized in revenue until the customer’s subsequent sales or usages occur.

Leases

The Company accounts for its lease under ASC 842, Leases, which generally requires the recognition of operating and financing lease liabilities with corresponding right-of-use assets on the balance sheet. See Note 6 for more information.

Research and development costs

Research and development costs include compensation and benefits for research and development employees, an allocation of overhead expenses and costs associated with materials and supplies used in clinical trials and research and development, outside contracted services including clinical and preclinical study costs, legal, regulatory compliance and fees paid to consultants or outside parties for research and development activities performed on the Company’s behalf. Such costs are charged to expense in the period in which they are incurred.

Research and development costs that are paid in advance of performance or receipt are recorded as prepaid expense and are amortized over the period that the services are performed.

Net loss per share

Net loss per share is calculated based on the weighted average number of common shares outstanding. Diluted net loss per share does not differ from basic net loss per share for the years ended December 31, 2025 and 2024, since the effect of including potential common shares would be anti-dilutive. For the year ended December 31, 2025, potential common shares of 14.0 million pertaining to outstanding stock options and unvested restricted stock units were excluded from the calculation of net loss per share. A total of approximately 16.9 million outstanding stock options and unvested restricted stock units were excluded from the calculation for the year ended December 31, 2024.

See Note 12 and Note 13 for more information about the Company’s common shares.

Deferred income taxes

Income taxes are accounted for using the asset and liability method of accounting. Deferred income taxes are recognized for the future income tax consequences attributable to differences between the carrying values of assets and liabilities and their respective income tax bases and for loss carry-forwards. Deferred income tax assets and liabilities are measured using enacted income tax rates expected to apply to taxable income in the periods in which temporary differences are expected to be recovered or settled. The effect on deferred income tax assets and liabilities of a change in tax laws or rates is included in earnings in the period that includes the enactment date. When realization of deferred income tax assets does not meet the more-likely-than-not criterion for recognition, a valuation allowance is provided.

Stock-based compensation

The Company measures and recognizes compensation expense for all share-based compensation arrangements based on estimated fair values. The Company uses the Black-Scholes option valuation model to estimate the fair value of stock options at the date of grant. The Black-Scholes option valuation model requires the input of subjective assumptions to calculate the value of stock options. For those assumptions, the Company uses historical data and other information to estimate the expected price volatility and risk-free interest rate for all awards. The expected life of stock options granted are estimated to be five years for employees and six years for directors and executives, based on the Company’s historical experience. Assumptions on the dividend yield are based on the fact that the Company has never paid cash dividends and has no present intention to pay cash dividends. The restricted stock units granted by the Company are measured at the grant-date price of the Company’s common shares. Expense is recognized over the vesting period for all awards and commences at the grant date for time-based awards. For awards where vesting may be accelerated if certain performance conditions are achieved, the Company will accelerate recognition of any unrecognized expense if and when it becomes probable that the performance conditions will be satisfied. Forfeitures are recognized as they occur.

For the Company’s Employee Stock Purchase Plan, the fair value of the right to acquire stock at a discounted price under the plan is calculated using the Black-Scholes valuation model. Expense is recognized over the period the employee contributes to the plan through payroll deductions.

Comprehensive loss

Comprehensive loss is comprised of net loss and adjustments for the change in unrealized gains and losses on investments in available-for-sale marketable securities. The Company includes comprehensive loss and its components in the consolidated statements of operations and comprehensive loss, net of tax effects if any.

Concentrations of Credit Risk

Financial instruments which potentially subject the Company to credit risk consist primarily of cash, cash equivalents and marketable securities. The Company holds these investments in highly rated financial institutions, and, by policy, limits the amounts of credit exposure to any one financial institution. These amounts at times may exceed federally insured limits. The Company has not experienced any credit losses in such accounts and does not believe it is exposed to any significant credit risk on these funds. The Company has no off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements.

Recent accounting pronouncements

In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (ASU 2023-09), which improves income tax disclosures by requiring: (1) consistent categories and greater disaggregation of information in the rate reconciliation, and (2) income taxes paid disaggregated by jurisdiction. It also includes certain other amendments to improve the effectiveness of income tax disclosures. ASU 2023-09 is effective for annual periods beginning after December 15, 2024. Early adoption is permitted. The ASU indicates that all entities will apply the guidance prospectively with an option for retroactive application to each period presented in the financial statements. The Company has implemented ASU 2023-09 for the year ended December 31, 2025 on a prospective basis. See Note 15 for more information.

The Company has reviewed all other recently issued standards and has determined that such standards will not have a material impact on the Company’s financial statements or do not otherwise apply to the Company’s operations.

Organization	12 Months Ended
Organization	Dec. 31, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Description of the Business Arbutus Biopharma Corporation (“Arbutus” or the “Company”) is a clinical-stage biopharmaceutical company focused on infectious disease. The Company is currently developing imdusiran (AB-729), its proprietary, GalNAc-conjugated, subcutaneously-delivered ribonucleic acid interference (RNAi) therapeutic, and AB-101, its proprietary oral PD-L1 inhibitor, for the treatment of chronic hepatitis B (cHBV). The Company continues to protect and defend its intellectual property, which is the subject of its ongoing lawsuit against Pfizer Inc. and BioNTech SE (collectively, Pfizer/BioNTech) for their use of the Company’s patented lipid nanoparticle (LNP) technology in their COVID-19 messenger ribonucleic acid interference (mRNA)-LNP vaccines. The court issued a claim construction ruling in September 2025, which construed the disputed claim terms in a manner the Company generally considers to be favorable. The parties are awaiting further scheduling in the litigation. On March 3, 2026, the Company, along with Genevant Sciences GmbH and its parent (collectively, Genevant), entered into a settlement agreement (the Moderna Settlement Agreement) to resolve all patent infringement litigation and patent revocation proceedings involving Moderna, Inc. and its affiliates (collectively, Moderna) pending in the United States and internationally (the Moderna LNP Litigation). Under the terms of the Moderna Settlement Agreement, Moderna will make an aggregate $950.0 million noncontingent lump sum payment (the Noncontingent Settlement Payment) to the Company and Genevant on or before July 8, 2026. In addition, Moderna is obligated to pay the Company and Genevant an additional aggregate contingent lump sum payment of $1.3 billion (the Contingent Settlement Payment) upon a ruling that is favorable to the Company and Genevant in a limited appeal related to 28 U.S.C. §1498 (§1498) that Moderna is allowed to file pursuant to the Moderna Settlement Agreement (the Moderna §1498 Appeal). Under the Company’s license with Genevant, it is entitled to receive, after deduction of litigation costs, 20% of the Noncontingent Settlement Payment. In addition, as of the date of this annual report, the Company owns approximately 16% of the outstanding common equity of Genevant. The Company is currently evaluating a return of capital to its shareholders in the third quarter of calendar year 2026, following the receipt of its portion of the Noncontingent Settlement Payment. Liquidity At December 31, 2025, the Company had an aggregate of $91.5 million in cash, cash equivalents and investments in marketable securities. The Company had no outstanding debt as of December 31, 2025. The Company believes it has sufficient cash resources to fund its operations for at least the next 12 months. The success of the Company’s operations is dependent on obtaining the necessary regulatory approvals to bring one or more of its product candidates to market and achieve profitability from operations. The Company’s development activities and the commercialization of its products are dependent on its ability to successfully complete these activities and to obtain adequate financing through a combination of financing activities and operations. It is not possible to predict either the outcome of the Company’s existing or future development programs or the Company’s ability to continue to fund these programs in the future.

Shareholders’ equity (Details) - USD ($) $ in Millions	12 Months Ended
Shareholders’ equity (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024	Nov. 06, 2024
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	1,164,000
Jefferies LLC \| Common Shares \| Dec 2024 Registration Statements
Class of Stock [Line Items]
Aggregate share sales price			$ 300.0
Jefferies LLC \| Common Shares \| Dec 2024 Prospectus Supplement \| Dec 2024 Registration Statements
Class of Stock [Line Items]
Aggregate share sales price			$ 100.0
Jefferies LLC \| Common Shares \| Sale Agreement
Class of Stock [Line Items]
Number of shares issued under agreement	0	16,499,999
Proceeds from issuance of common stock		$ 44.1

Segment Reporting (Details) $ in Thousands	12 Months Ended
Segment Reporting (Details) $ in Thousands	Dec. 31, 2025 USD ($) numberOfSegments	Dec. 31, 2024 USD ($)
Segment Reporting [Abstract]
Number of reportable segments \| numberOfSegments	1
Segment Reporting Information [Line Items]
Total revenue	$ 14,083	$ 6,171
General and administrative	15,893	22,108
Gain on sale of property and equipment	674	0
Adjustments and reconciling items	0	0
Consolidated net loss	(33,501)	(69,920)
Reportable Segment
Segment Reporting Information [Line Items]
Total revenue	14,083	6,171
Research and development employee expense, lab supplies and overhead	13,961	26,613
Imdusiran IM-PROVE I, II & III clinical trials expense	4,824	15,735
AB-101-001 Phase 1a/1b clinical trial expense	6,220	10,196
Other early research and development programs expense	236	1,493
General and administrative	15,893	22,108
Restructuring expense	12,939	3,720
Other segment expense	(1,747)	2,811
Interest income	4,068	6,585
Gain on sale of property and equipment	674	0
Segment Reporting Information, Profit (Loss) [Abstract]	(33,501)	(69,920)
Consolidated net loss	$ (33,501)	$ (69,920)

Restructuring (Details) $ in Thousands	12 Months Ended
Restructuring (Details) $ in Thousands	Dec. 31, 2025 USD ($) employee	Dec. 31, 2024 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 12,939	$ 3,720
Restructuring And Workforce Reduction
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated \| employee	19
Restructuring costs	$ 12,939	3,720
Restructuring And Workforce Reduction \| Severance and continuing benefits
Restructuring Cost and Reserve [Line Items]
Restructuring costs	6,331	2,857
Restructuring And Workforce Reduction \| Non-cash stock compensation modification expense
Restructuring Cost and Reserve [Line Items]
Restructuring costs	2,483	0
Restructuring And Workforce Reduction \| Non-cash impairment of leasehold improvements and laboratory equipment
Restructuring Cost and Reserve [Line Items]
Restructuring costs	2,811	167
Restructuring And Workforce Reduction \| Non-cash impairment of lease right-of-use asset
Restructuring Cost and Reserve [Line Items]
Restructuring costs	948	0
Restructuring And Workforce Reduction \| Accrual of lease-related operating expenses
Restructuring Cost and Reserve [Line Items]
Restructuring costs	364	0
Restructuring And Workforce Reduction \| Contract close-out costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 0	$ 696

Fair value measurements - Assets and liabilities measured at fair value on recurring basis (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Assets
Cash and cash equivalents	$ 18,008	$ 36,330
Investments in marketable securities, current	73,463	86,293
Investments in marketable securities, non-current	0	0
Total	91,471	122,623
Liabilities
Contingent consideration	8,395	10,225	$ 7,600
Total	8,395	10,225
Level 1
Assets
Cash and cash equivalents	18,008	36,330
Investments in marketable securities, current	0	0
Total	18,008	36,330
Liabilities
Contingent consideration	0	0
Total	0	0
Level 2
Assets
Cash and cash equivalents	0	0
Investments in marketable securities, current	73,463	86,293
Total	73,463	86,293
Liabilities
Contingent consideration	0	0
Total	0	0
Level 3
Assets
Cash and cash equivalents	0	0
Investments in marketable securities, current	0	0
Total	0	0
Liabilities
Contingent consideration	8,395	10,225
Total	$ 8,395	$ 10,225

Property and equipment

12 Months Ended

Dec. 31, 2025

Property, Plant and Equipment [Abstract]

Property and equipment

During the year ended December 31, 2025 and related to its 2025 restructuring and planned exit from its corporate headquarters in Warminster, Pennsylvania (Note 16), the Company recorded impairment charges of $1.9 million and $0.9 million for leasehold improvements and laboratory equipment, respectively. In connection with the exit from the building and disposal of equipment, the Company also wrote off the fully-depreciated or fully-impaired balances associated with these assets in 2025.

The Company’s property and equipment balances as of the years ended December 31, 2025 and 2024 were as follows:


	Cost		Accumulated depreciation		Net book value
December 31, 2025	(in thousands)
Lab equipment	$	—	$	—	$	—
Leasehold improvements	—		—		—
Computer hardware and software	245		(213)		32
	$	245	$	(213)	$	32


	Cost		Accumulated depreciation		Net book value
December 31, 2024	(in thousands)
Lab equipment	$	7,238	$	(6,105)	$	1,133
Leasehold improvements	8,590		(6,489)		2,101
Computer hardware and software	477		(402)		75
	$	16,305	$	(12,996)	$	3,309

Depreciation expense for the years ended December 31, 2025 and 2024 was $0.4 million and $1.4 million, respectively.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2025
Subsequent Events [Abstract]
Subsequent events	Subsequent Events On March 3, 2026, subsequent to the Company’s December 31, 2025 balance sheet date, the Company and Genevant entered into the Moderna Settlement Agreement to resolve the Moderna LNP Litigation. As part of the Moderna Settlement Agreement, the Company and Genevant will receive an aggregate $950 million Noncontingent Settlement Payment in July 2026. This portion of the settlement is noncreditable and nonrefundable. In addition, the Company and Genevant are entitled to receive an additional Contingent Settlement Payment of up to an aggregate $1.3 billion upon the occurrence of certain events related to the Moderna §1498 Appeal, but which may be subject to repayment. Under the Genevant License, the Company is entitled to receive, after reimbursement of both the Company’s and Genevant’s litigation costs, 20% of the Noncontingent Settlement Payment. As of December 31, 2025, the Company owns approximately 16% of the outstanding common equity of Genevant. As the settlement was executed after December 31, 2025, no amounts related to the settlement have been reflected in the accompanying consolidated financial statements.

Significant accounting policies (Tables)

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Schedule of estimated useful lives of property and equipment

The Company records depreciation using the straight-line method over the estimated useful lives of the capital assets as follows:


	Useful Life (Years)
Laboratory equipment		5
Computer and office equipment	2	to	5
Furniture and fixtures		5

Significant accounting policies - Narrative (Details) shares in Millions	12 Months Ended
	Dec. 31, 2025 USD ($) subsidiary shares	Dec. 31, 2024 shares
Accounting Policies [Abstract]
Number of wholly-owned subsidiaries \| subsidiary	1
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of wholly-owned subsidiaries \| subsidiary	1
Equity method investments \| $	$ 0
Anti-dilutive common shares excluded from calculation of income per common share (in shares) \| shares	14.0	16.9
Options outstanding and expected to vest \| Directors and Executives
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Expected life (in years)	6 years
Options outstanding and expected to vest \| Employee
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Expected life (in years)	5 years
Genevant
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Ownership interest in equity method investment (as a percent)	16.00%
Equity method investments \| $	$ 0

Accounts payable and accrued liabilities (Tables)

12 Months Ended

Dec. 31, 2025

Payables and Accruals [Abstract]

Schedule of accounts payable and accrued liabilities

Accounts payable and accrued liabilities were comprised of the following:


	December 31, 2025		December 31, 2024
	(in thousands)
Trade accounts payable	$	1,173	$	2,316
Payroll accruals	2,159		3,393
Research and development accruals	412		691
Professional fee accruals	1,075		1,164
Restructuring liabilities	640		—
Total	$	5,459	$	7,564

Income taxes (Tables)

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Schedule of income before income tax, domestic and foreign

The domestic and foreign components of loss before income taxes were as follows:


	Year ended December 31,
	2025		2024
	(in thousands)
Domestic	$	11,952	$	(1,671)
Foreign	$	(45,453)	$	(68,249)
Loss before income taxes	$	(33,501)	$	(69,920)

Schedule of effective income tax rate reconciliation

A reconciliation of the Canadian federal statutory income tax rate to the effective tax rate for the year ended December 31, 2025 in accordance with the guidance in ASU 2023-09 is as follows:


	Year Ended December 31, 2025
	(in thousands, except percentages)
Computed taxes (benefits) at Canadian federal rates	$	(8,374)	25	%
Domestic tax effects:
Change in valuation allowance	(2,540)		8	%
Other	(449)		1	%
Domestic provincial tax effects:
Tax abatement	(1,195)		4	%
Provincial tax	1,435		(4)	%
Change in valuation allowance	(203)		1	%
Other	(36)		—	%
Foreign tax effects:
United States
Foreign tax rate differential	1,818		(5)	%
Non-taxable and non-deductible items: stock options	879		(3)	%
Tax credits: research and development credits	(403)		1	%
Changes in valuation allowance	8,706		(26)	%
Other adjustments:
Stock option adjustment	304		(1)	%
Other	58		—	%
Effective tax rate	$	—	—	%


	Year Ended December 31, 2024
	(in thousands)
Computed taxes (benefits) at Canadian federal and provincial tax rates	$	(18,888)

Permanent and other differences	515
Federal R&D credit	(1,122)


Change in valuation allowance	11,748
Difference due to income taxed at foreign rates	4,101
Stock-based compensation	1,327
Other	2,319
Income tax expense	$	—

Schedule of components of deferred tax assets

Significant components of the Company’s deferred tax assets and liabilities are shown below:


	As of December 31,
	2025		2024
	(in thousands)
Deferred tax assets (liabilities):
Operating loss carryforwards	$	111,292	$	96,075
Canadian research and development deductions	16,673		16,700
Book amortization in excess of tax	308		(232)
Revenue recognized for tax purposes in excess of revenue recognized for accounting purposes	929		1,296
Tax value in excess of accounting value in lease inducements	157		51
Deferred revenue	—		2,817
Canadian Federal investment tax credits	5,147		5,147
Canadian Provincial investment tax credits	1,953		1,953
Equity method investment	3,375		3,375
U.S. Federal research and development credits	8,677		8,310
Deductible stock options	3,559		4,037
U.S. research and experimental expenditures capitalization	27,188		33,707
Accrued interest payable	1,869		1,796
Amortization	191		256
Other	72		138
Total deferred tax assets	$	181,390	$	175,426
Valuation allowance	(181,390)		(175,426)
Net deferred tax assets (liabilities)	$	—	$	—

Collaborations and royalty entitlements (Tables)

12 Months Ended

Dec. 31, 2025

Revenue from Contract with Customer [Abstract]

Schedule of revenue recognized under collaborations, contracts and licensing agreements

Revenues from the Company’s royalty entitlements are summarized in the following table:


	Year ended December 31,
	2025		2024
	(in thousands)
Revenue from collaborations and licenses
Royalties from sales of ONPATTRO	$	1,667	$	2,562
Qilu Pharmaceutical Co., Ltd.	10,434		1,357
Other milestone and royalty payments	500		—
Non-cash royalty revenue
Royalties from sales of ONPATTRO	1,482		2,252
Total revenue	$	14,083	$	6,171

Sale of future royalties (Tables)

12 Months Ended

Dec. 31, 2025

Other Liabilities Disclosure [Abstract]

Activity related to net liability

The table below shows the activity related to the net liability for the years ended December 31, 2025 and December 31, 2024:


	Twelve Months Ended December 31,
	2025		2024
	(in thousands)
Net liability related to sale of future royalties - beginning balance	$	4,829	$	6,953
Non-cash royalty revenue	(1,482)		(2,251)
Non-cash interest expense	95		127
Net liability related to sale of future royalties - ending balance	$	3,442	$	4,829

Subsequent Events (Details) - Subsequent event - Moderna V. Genevant's And Arbutus' LNP Delivery Technology $ in Millions	Mar. 03, 2026 USD ($)
Settled Litigation
Subsequent Event [Line Items]
Percent of litigation settlement to be received after costs	0.20
Settled Litigation \| Genevant
Subsequent Event [Line Items]
Litigation settlement amount awarded	$ 950
Pending Litigation \| Genevant
Subsequent Event [Line Items]
Additional damages sought, pending appeals process	$ 1,300

Fair value measurements

12 Months Ended

Dec. 31, 2025

Fair Value Disclosures [Abstract]

Fair value measurements

The Company measures certain financial instruments and other items at fair value.

To determine the fair value, the Company uses the fair value 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 inputs market participants would use to value an asset or liability and are developed based on market data obtained from independent sources. Unobservable inputs are inputs based on assumptions about the factors market participants would use to value an asset or liability. The three levels of inputs that may be used to measure fair value are as follows:

•Level 1 inputs are quoted market prices for identical instruments available in active markets. The Company’s cash and cash equivalents are measured using Level 1 inputs.

•Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability either directly or indirectly. If the asset or liability has a contractual term, the input must be observable for substantially the full term. An example includes quoted market prices for similar assets or liabilities in active markets. The Company’s investments in marketable securities are measured using Level 2 inputs.

•Level 3 inputs are unobservable inputs for the asset or liability and will reflect management’s assumptions about market assumptions that would be used to price the asset or liability. The Company’s liability-classified options and contingent consideration are measured using Level 3 inputs.

Assets and liabilities are classified based on the lowest level of input that is significant to the fair value measurements. Changes in the observability of valuation inputs may result in a reclassification of levels for certain securities within the fair value hierarchy.

The carrying values of cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities approximate their fair values due to the immediate or short-term maturity of these financial instruments.

To determine the fair value of the contingent consideration related to a stock purchase agreement with Enantigen Therapeutics, Inc.’s (Enantigen) selling shareholders (Note 10), the Company uses a probability weighted assessment that considers the likelihood of successfully commercializing a treatment for cHBV, the timing of future revenues related to commercial sales, and a probability adjusted discount rate that reflects the early stage nature of the development program, time to complete the program development, and overall biotech indices.

The following table presents information about inputs used in measuring the fair value of the contingent consideration:


	As of December 31, 2025				As of December 31, 2024
Timing of milestone payments	2035		-	2038	2032		-	2035
Payment (in $000s)	$102,500				$102,500
Discount rate	10.1	%	-	10.4%	9.9	%	-	10.5%
Probability of success	25%				25%
Fair value of contingent consideration (in $000s)	$8,395				$10,225

These assumptions used in the discounted cash flow model are level 3 inputs as defined above. The Company assessed the sensitivity of the fair value measurement to changes in these unobservable inputs and determined that changes within a reasonable range would not result in a materially different assessment of fair value.

The following tables present information about the Company’s assets and liabilities that are measured at fair value on a recurring basis, and indicates the fair value hierarchy of the valuation techniques used to determine such fair value:


	Level 1		Level 2		Level 3		Total
As of December 31, 2025	(in thousands)
Assets
Cash and cash equivalents	$	18,008	$	—	$	—	$	18,008
Investments in marketable securities, current	—		73,463		—		73,463

Total	$	18,008	$	73,463	$	—	$	91,471
Liabilities
Contingent consideration	—		—		8,395		8,395
Total	$	—	$	—	$	8,395	$	8,395


	Level 1		Level 2		Level 3		Total
As of December 31, 2024	(in thousands)
Assets
Cash and cash equivalents	$	36,330	$	—	$	—	$	36,330
Investments in marketable securities, current	—		86,293		—		86,293

Total	$	36,330	$	86,293	$	—	$	122,623
Liabilities
Contingent consideration	—		—		10,225		10,225
Total	$	—	$	—	$	10,225	$	10,225

The following table presents the changes in fair value of the Company’s contingent consideration:


	Liability at beginning of the period		Increase in fair value of liability		Liability at end of the period
	(in thousands)
Year ended December 31, 2025	$	10,225	$	(1,830)	$	8,395
Year ended December 31, 2024	$	7,600	$	2,625	$	10,225

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 107
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-107

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 100
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-100

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 6A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 940
-SubTopic 820
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478119/940-820-50-1

+ Details

Investments in marketable securities (Tables)

12 Months Ended

Dec. 31, 2025

Investments, Debt and Equity Securities [Abstract]

Investments in marketable securities

Investments in marketable securities and cash equivalents consisted of the following:


	Amortized Cost		Gross Unrealized Gain(1)		Gross Unrealized Loss(1)		Fair Value
As of December 31, 2025	(in thousands)
Cash equivalents
Money market funds	$	10,218	$	—	$	—	$	10,218
Total	$	10,218	$	—	$	—	$	10,218
Investments in marketable short-term securities


US treasury bills	$	37,411	$	41	$	—	$	37,452
US government bonds	35,965		46		—		36,011
Total	$	73,376	$	87	$	—	$	73,463

(1) Gross unrealized gain (loss) is pre-tax and is reported in accumulated other comprehensive loss.


	Amortized Cost		Gross Unrealized Gain(1)		Gross Unrealized Loss(1)		Fair Value
As of December 31, 2024	(in thousands)
Cash equivalents
Money market fund	$	29,533	$	—	$	—	$	29,533
Total	$	29,533	$	—	$	—	$	29,533
Investments in marketable short-term securities

US corporate bonds	$	30,776	$	27	$	(6)	$	30,797

US treasury bills	55,467		29				55,496

Total	$	86,243	$	56	$	(6)	$	86,293

(1) Gross unrealized gain (loss) is pre-tax and is reported in accumulated other comprehensive loss.

Restructuring (Tables)

12 Months Ended

Dec. 31, 2025

Restructuring and Related Activities [Abstract]

Restructuring and Related Costs

Significant components of the Company’s restructuring charges are shown below:


	Year ended December 31,
	2025		2024
	(in thousands)
Severance and continuing benefits	$	6,331	$	2,857
Non-cash stock compensation modification expense	2,483		—
Non-cash impairment of leasehold improvements and laboratory equipment	2,811		167
Non-cash impairment of lease right-of-use asset	948		—
Accrual of lease-related operating expenses	364		—
Contract close-out costs	—		696
Total restructuring charges	$	12,939	$	3,720

Fair value measurements - Valuation (Details) $ in Thousands	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of contingent consideration (in $000s)	$ 8,395	$ 10,225	$ 7,600
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of contingent consideration (in $000s)	8,395	10,225
Level 3 \| Enantigen Therapeutics, Inc
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Payment (in $000s)	$ 102,500	$ 102,500
Level 3 \| Probability of success
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration, liability, measurement input	0.25	0.25
Minimum \| Level 3 \| Discount rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration, liability, measurement input	0.101	0.099
Maximum \| Level 3 \| Discount rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration, liability, measurement input	0.104	0.105

Significant accounting policies (Policies)

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Basis of presentation

Principles of consolidation

All intercompany balances and transactions have been eliminated.

Use of estimates

Cash and cash equivalents

Investments in marketable securities

All investments are governed by the Company’s Investment Policy approved by the Company’s Board of Directors (the Board).

Foreign currency translation and functional currency conversion

Investment in Genevant

Property and equipment


	Useful Life (Years)
Laboratory equipment		5
Computer and office equipment	2	to	5
Furniture and fixtures		5

Leasehold improvements are depreciated over their estimated useful lives but in no case longer than the lease term, except where lease renewal is reasonably assured.

Impairment of property and equipment

Substantially all of the Company’s premises, property and equipment are located in the United States.

See Note 7 for more information.

Revenue from collaborations and licenses

specific exception in the revenue standards, whereby the consideration is not included in the transaction price and recognized in revenue until the customer’s subsequent sales or usages occur.

Leases

Research and development costs

Research and development costs that are paid in advance of performance or receipt are recorded as prepaid expense and are amortized over the period that the services are performed.

Net loss attributable to common shareholders per share

Net loss per share

Deferred income taxes

Stock-based compensation

Comprehensive loss

Concentrations of Credit Risk

Recent accounting pronouncements

Collaborations and royalty entitlements - Summary of revenues (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total revenue	$ 14,083	$ 6,171
License \| Royalties from sales of ONPATTRO
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total revenue	1,667	2,562
License \| Qilu Pharmaceutical Co., Ltd.
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total revenue	10,434	1,357
License \| Other milestone and royalty payments
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total revenue	500	0
Non-cash royalty revenue
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total revenue	1,482	2,252
Non-cash royalty revenue \| Royalties from sales of ONPATTRO
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total revenue	$ 1,482	$ 2,252

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4A
-Subparagraph (c)
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147477548/944-605-55-14

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-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(5))
-Publisher FASB
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Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(i))
-Publisher FASB
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(A))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1B

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(B))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1B

Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Section S99
-Paragraph 1B
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-Publisher FASB
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Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
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-Publisher FASB
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Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-30

Reference 29: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Section 50
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-Subparagraph (b)
-Publisher FASB
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Reference 30: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 40
-Publisher FASB
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Reference 31: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-22

Reference 32: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2

+ Details

Stock-based compensation - Stock options outstanding under the Arbutus Plan (Details) - Arbutus Plans $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2025 USD ($) $ / shares shares
Options outstanding and expected to vest
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of options outstanding (in shares) \| shares	12,430,999
Options outstanding, Weighted average exercise price (in USD per share) \| $ / shares	$ 3.39
Intrinsic value of stock options \| $	$ 18,345
Weighted-average term remaining	6 years 2 months 12 days
Vested stock options
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of options outstanding (in shares) \| shares	9,146,505
Options outstanding, Weighted average exercise price (in USD per share) \| $ / shares	$ 3.44
Intrinsic value of stock options \| $	$ 13,243
Weighted-average term remaining	5 years 2 months 12 days

Related party transactions	12 Months Ended
Related party transactions	Dec. 31, 2025
Related Party Transactions [Abstract]
Related party transactions	Related Party Transaction On August 5, 2025, the Company entered into an agreement with Keith Manchester, M.D. for consulting services regarding the Company’s development strategy and its hepatitis B programs. Dr. Manchester served as a member of the Board until February 24, 2025 and is considered a related person due to his service on the Board during the fiscal year ended December 31, 2025. In connection with this agreement, the Company granted an option to purchase 400,000 common shares to Dr. Manchester, with 5/48ths vesting immediately and the remainder vesting monthly. Vesting of all unvested shares may be accelerated if certain performance conditions are achieved, at the discretion of the Board. The grant date fair value of the award was calculated using the Black-Scholes option valuation model, and expense will be recognized over the expected service period. The Company will accelerate recognition of any unrecognized expense if and when it becomes probable that the performance conditions will be satisfied.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480990/946-20-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480990/946-20-50-5

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480990/946-20-50-6

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477968/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477968/946-235-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(g)(3))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(e))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/850/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-6

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

+ Details

Segment Reporting (Tables)

12 Months Ended

Dec. 31, 2025

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment


	Year ended December 31,
	2025		2024
	(in thousands)
Revenue	$	14,083	$	6,171
Less:
Research and development employee expense, lab supplies and overhead	13,961		26,613
Imdusiran IM-PROVE I, II & III clinical trials expense	4,824		15,735
AB-101-001 Phase 1a/1b clinical trial expense	6,220		10,196
Other early research and development programs expense	236		1,493
General and administrative expense	15,893		22,108
Restructuring expense	12,939		3,720
Other segment expense (1)	(1,747)		2,811
Add:
Interest income	4,068		6,585
Gain on sale of property and equipment	674		—
Segment net loss	$	(33,501)	$	(69,920)
Adjustments and reconciling items	—		—
Consolidated net loss	$	(33,501)	$	(69,920)

(1) Other segment expense includes the change in the fair value of contingent consideration, non-cash interest expenses and foreign currency exchange gains and losses.

Stock-based compensation - Narrative (Details) - USD ($)		12 Months Ended
	Jul. 10, 2023	Dec. 31, 2025	Dec. 31, 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock-based compensation awards approved to be issued (in shares)		40,493,870
Restricted stock units (in shares)		1,529,959
Common shares reserved for issuance		1,500,000
Discount rate on shares		15.00%
Issuance of common shares pursuant to exercise of ESPP options (in shares)		60,493	227,333
Number of shares remaining for issuance		554,175
Stock-based compensation expense related to ESPP (less than)		$ 100,000	$ 100,000
Stock-based compensation expense		6,953,000	$ 8,986,000
Plan modification cost		2,500,000
Options outstanding and expected to vest
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unearned compensation expense		$ 6,300,000
Unearned compensation expense, recognition period		2 years 10 months 24 days
Naftzger Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)	500,000
Arbutus Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)		5 years 8 months 12 days	5 years 7 months 6 days
Intrinsic value of options exercised		$ 1,800,000	$ 1,400,000
Arbutus Plans \| Options outstanding and expected to vest
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)		12,430,999	15,451,687
Options granted (in shares)		5,263,722
Options granted - Weighted average exercise price (in CAD and USD per share)		$ 3.33
Options outstanding and expected to vest
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)		12,430,999
Number of additional shares authorized (in shares)		16,881,800
Options outstanding and expected to vest \| 2016 and 2011 Plans \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)		10 years
Options outstanding and expected to vest \| 2016 and 2011 Plans \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period (in years)		4 years
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares authorized (in shares)		16,881,800
Unearned compensation expense		$ 4,100,000
Unearned compensation expense, recognition period			1 year 8 months 12 days
Restricted Stock Units (RSUs) \| Arbutus Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units (in shares)		1,529,959	1,493,136
Weighted average grant date fair value (in dollars per share)		$ 3.58	$ 2.40
Performance shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 0	$ 0

Investments in marketable securities (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents	$ 18,008	$ 36,330
Cash Equivalents, Fair Value	18,008	36,330
Amortized Cost	73,376	86,243
Gross Unrealized Gain	87	56
Gross Unrealized Loss	0	(6)
Fair Value	73,463	86,293
Money market funds
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents	10,218	29,533
Cash Equivalents, Fair Value	10,218	29,533
US treasury bills
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	37,411	55,467
Gross Unrealized Gain	41	29
Gross Unrealized Loss	0
Fair Value	37,452	55,496
US government bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	35,965
Gross Unrealized Gain	46
Gross Unrealized Loss	0
Fair Value	$ 36,011
US corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		30,776
Gross Unrealized Gain		27
Gross Unrealized Loss		(6)
Fair Value		$ 30,797

Contingencies and commitments	12 Months Ended
Contingencies and commitments	Dec. 31, 2025
Commitments and Contingencies Disclosure [Abstract]
Contingencies and commitments	Contingencies and commitments Stock Purchase Agreement with Enantigen In October 2014, Arbutus Inc., the Company’s wholly-owned subsidiary, acquired all of the outstanding shares of Enantigen pursuant to a stock purchase agreement. The amount paid to Enantigen’s selling shareholders could be up to an additional $102.5 million in sales performance milestones in connection with the sale of the first commercialized product by Arbutus for the treatment of HBV, regardless of whether such product is based upon assets acquired under this agreement, and a low single-digit royalty on net sales of such first commercialized HBV product, up to a maximum royalty payment of $1.0 million that, if paid, would be offset against Arbutus’ milestone payment obligations. Certain other development milestones related to the acquisition were tied to programs which are no longer under development by Arbutus, and therefore the contingency related to those development milestones is zero. The contingent consideration is a financial liability and is measured at its fair value at each reporting period, with any changes in fair value from the previous reporting period recorded in the statement of operations and comprehensive loss (Note 3). The fair value of the contingent consideration was $8.4 million as of December 31, 2025.

Significant accounting policies - Estimated useful lives of property and equipment (Details)	Dec. 31, 2025
Laboratory equipment
Property, Plant and Equipment [Line Items]
Useful lives (in years)	5 years
Computer and office equipment \| Minimum
Property, Plant and Equipment [Line Items]
Useful lives (in years)	2 years
Computer and office equipment \| Maximum
Property, Plant and Equipment [Line Items]
Useful lives (in years)	5 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Useful lives (in years)	5 years

Sale of future royalties - Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Liability Related To Future Royalties [Roll Forward]
Net liability related to sale of future royalties - beginning balance	$ 4,829	$ 6,953
Non-cash royalty revenue	(1,482)	(2,251)
Non-cash interest expense	95	127
Net liability related to sale of future royalties - ending balance	3,442	$ 4,829
ONPATTRO, global net sales
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Annual Revenue Threshold	500,000
Annual Revenue Threshold	$ 500,000

Leases - Lease cost (Details) - USD ($) $ in Thousands	12 Months Ended
Leases - Lease cost (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Leases [Abstract]
Weighted-average remaining lease term (years)	1 year 3 months 18 days
Weighted average discount rate	9.00%
Cash paid for amounts included in the measurement of lease liabilities	$ 634	$ 616
Fixed lease payment	$ 200	$ 500

Accounts payable and accrued liabilities - Restructuring (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 12,939	$ 3,720
Restructuring And Workforce Reduction
Restructuring Cost and Reserve [Line Items]
Restructuring costs	12,939	$ 3,720
Restructuring And Workforce Reduction \| Severance And Employee Benefit Costs and Lease Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ (600)

- Definition

Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

+ References + Details

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Investment in Genevant (Details)	12 Months Ended
Investment in Genevant (Details)	Dec. 31, 2025 USD ($)
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 0
Genevant
Schedule of Equity Method Investments [Line Items]
Sub-licensing revenue, percentage	20.00%
Bona fide collaboration Percentage [Member]	14.00%
Equity method investments	$ 0
Ownership interest in equity method investment (as a percent)	16.00%

- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References + Details

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Sale of future royalties

12 Months Ended

Dec. 31, 2025

Other Liabilities Disclosure [Abstract]

Sale of future royalties

On July 2, 2019, the Company entered into a Purchase and Sale Agreement (the Agreement) with the Ontario Municipal Employees Retirement System (OMERS), pursuant to which the Company sold to OMERS part of its royalty interest on future global net sales of ONPATTRO (Patisiran) (ONPATTRO), an RNA interference therapeutic currently being sold by Alnylam Pharmaceuticals, Inc. (Alnylam).

ONPATTRO utilizes Arbutus’s LNP technology, which was licensed to Alnylam pursuant to the Cross-License Agreement, dated November 12, 2012, by and between the Company and Alnylam (the LNP License Agreement). Under the terms of the LNP License Agreement, the Company is entitled to tiered royalty payments on global net sales of ONPATTRO ranging from 1.00% to 2.33% after offsets, with the highest tier applicable to annual net sales above $500 million. This royalty interest was sold to OMERS, effective as of January 1, 2019, for $20 million in gross proceeds before advisory fees. OMERS will retain this entitlement until it has received $30 million in royalties, at which point 100% of such royalty interest on future global net sales of ONPATTRO will revert to the Company. OMERS has assumed the risk of collecting up to $30 million of future royalty payments from Alnylam and Arbutus is not obligated to reimburse OMERS if they fail to collect any such future royalties.

The $30 million in royalties to be paid to OMERS is accounted for as a liability, with the difference between the liability and the gross proceeds received accounted for as a discount. The discount, as well as $1.5 million of transaction costs, will be amortized as interest expense based on the projected balance of the liability as of the beginning of each period. As of December 31, 2025, the Company estimated an effective annual interest rate of approximately 2.1%. Over the course of the Agreement, the actual interest rate will be affected by the amount and timing of royalty revenue recognized and changes in the timing of forecasted royalty revenue. On a quarterly basis, the Company will reassess the expected timing of the royalty revenue, recalculate the amortization and effective interest rate and adjust the accounting prospectively as needed.

The Company recognizes non-cash royalty revenue related to the sales of ONPATTRO during the term of the Agreement. As royalties are remitted to OMERS from Alnylam, the balance of the recognized liability is effectively repaid over the life of the Agreement. From the inception of the royalty sale through December 31, 2025, an aggregate of $26.5 million of royalties have been earned by OMERS. There are a number of factors that could materially affect the amount and timing of royalty payments from Alnylam, none of which are within the Company’s control.

During the year ended December 31, 2025, the Company recognized non-cash royalty revenue of $1.5 million and $0.1 million of related non-cash interest expense. During the year ended December 31, 2024, the Company recognized non-cash royalty revenue of $2.3 million and related non-cash interest expense of $0.1 million.

The table below shows the activity related to the net liability for the years ended December 31, 2025 and December 31, 2024:


	Twelve Months Ended December 31,
	2025		2024
	(in thousands)
Net liability related to sale of future royalties - beginning balance	$	4,829	$	6,953
Non-cash royalty revenue	(1,482)		(2,251)
Non-cash interest expense	95		127
Net liability related to sale of future royalties - ending balance	$	3,442	$	4,829

In addition to the royalty from the LNP License Agreement, the Company is also receiving a second royalty interest ranging from 0.75% to 1.125% on global net sales of ONPATTRO, with 0.75% applying to sales greater than $500 million, originating from a settlement agreement and subsequent license agreement with Acuitas Therapeutics, Inc. (Acuitas). The royalty from Acuitas has been retained by the Company and was not part of the royalty sale to OMERS. In addition to the two royalty entitlements, the Company is entitled to receive payments upon the achievement of contractual milestones related to Alnylam’s use of the Company’s proprietary LNP technology for other products.

Cover - USD ($)	12 Months Ended
Cover - USD ($)	Dec. 31, 2025	Mar. 18, 2026	Jun. 30, 2025
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2025
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-34949
Entity Registrant Name	Arbutus Biopharma Corp
Entity Incorporation, State or Country Code	A1
Entity Tax Identification Number	98-0597776
Entity Address, Address Line One	701 Veterans Circle
Entity Address, City or Town	Warminster
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	18974
City Area Code	267
Local Phone Number	469-0914
Title of 12(b) Security	Common shares, without par value
Trading Symbol	ABUS
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 472,133,611
Shares price (in USD per share)			$ 3.09
Entity Common Stock, Shares Outstanding		195,478,068
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s definitive proxy statement for its 2026 Annual General Meeting of Shareholders, which the registrant intends to file pursuant to Regulation 14A with the Securities and Exchange Commission no later than 120 days after the registrant’s fiscal year ended December 31, 2025, are incorporated by reference into Part III of this Form 10-K.
Amendment Flag	false
Entity Central Index Key	0001447028
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Document Financial Statement Error Correction [Flag]	false

Fair value measurements - Changes in fair value of contingent consideration (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Fair Value, Liabilities Measured on Recurring Basis [Roll Forward]
Liability at beginning of the period	$ 10,225	$ 7,600
Increase in fair value of liability	(1,830)	2,625
Liability at end of the period	$ 8,395	$ 10,225

Shareholders’ equity	12 Months Ended
Shareholders’ equity	Dec. 31, 2025
Equity [Abstract]
Shareholders' equity	Shareholders’ equity Authorized share capital The Company’s authorized share capital consists of an unlimited number of common shares and preferred shares, without par value, and 1,164,000 Series A participating convertible preferred shares, without par value. Open Market Sale Agreement Effective March 26, 2025, the Company terminated its Open Market Sale Agreement with Jefferies LLC (Jefferies) dated December 20, 2018, as amended by Amendment No. 1, dated December 20, 2019, Amendment No. 2, dated August 7, 2020 and Amendment No. 3, dated March 4, 2021 (as amended, the Sale Agreement), under which the Company could issue and sell common shares, from time to time. Previously, on November 6, 2024, the Company filed: i) a shelf registration statement on Form S-3 with the SEC (File No. 333-283038) with an accompanying base prospectus, declared effective by the SEC on December 5, 2024 (the December 2024 Registration Statement), for the offer and sale of up to $300.0 million of the Company’s securities; and ii) a prospectus supplement with the SEC in connection with the offering of up to $100.0 million of the Company’s common shares pursuant to the Sale Agreement under the December 2024 Registration Statement (the December 2024 Prospectus Supplement). The Company did not utilize any of the December 2024 Prospectus Supplement pursuant to the Sale Agreement prior to the termination of the Sale Agreement. During the year ended December 31, 2024, the Company issued 16,499,999 common shares under the Sale Agreement, resulting in net proceeds of approximately $44.1 million. During the year ended 2025, the Company issued no common shares under the Sale Agreement.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-8A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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+ Details

Investments in marketable securities - narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2025 USD ($) numberOfSegments	Dec. 31, 2024 USD ($) numberOfSegments
Investments, Debt and Equity Securities [Abstract]
Fair Value	$ 73,463	$ 86,293
Investments in marketable securities, non-current	$ 0	$ 0
Number of loss positions \| numberOfSegments	0	6
Accrued Investment Income Receivable	$ (300)	$ (300)
Debt Securities, Realized Gain (Loss)	$ 100	$ 100

- Definition

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+ Details

Restructuring

12 Months Ended

Dec. 31, 2025

Restructuring and Related Activities [Abstract]

Restructuring

In both 2024 and 2025, the Company implemented changes to focus its efforts on advancing the clinical development of imdusiran and AB-101 by ceasing all discovery efforts, implementing workforce reductions, and halting preparations for a potential IM-PROVE III clinical trial. In 2025, the decision was made to exit the Company’s corporate headquarters in Warminster, Pennsylvania and to discontinue in-house scientific research. The restructuring has resulted in a total workforce after reductions of 19 employees.

Significant components of the Company’s restructuring charges are shown below:


	Year ended December 31,
	2025		2024
	(in thousands)
Severance and continuing benefits	$	6,331	$	2,857
Non-cash stock compensation modification expense	2,483		—
Non-cash impairment of leasehold improvements and laboratory equipment	2,811		167
Non-cash impairment of lease right-of-use asset	948		—
Accrual of lease-related operating expenses	364		—
Contract close-out costs	—		696
Total restructuring charges	$	12,939	$	3,720

Organization (Details) - USD ($)	Jan. 05, 2022	Dec. 31, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash, cash equivalents and short-term investments		$ 91,500,000
Outstanding debt		$ 0
One-Time Upfront Cash Payment \| Qilu
Class of Stock [Line Items]
Cash payment for collaborations	$ 40,000,000.0

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Significant accounting policies - Computation of basic and diluted net income (loss) per common share (Details) - $ / shares	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted average number of common shares - basic (in shares)	191,599,600	185,608,874
Weighted average number of common shares - diluted (in shares)	191,599,600	185,608,874
Basic net loss attributable to common shareholders per share (in USD per share)	$ (0.17)	$ (0.38)
Diluted net loss attributable to common shareholders per share (in USD per share)	$ (0.17)	$ (0.38)

- Definition

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Stock-based compensation

12 Months Ended

Dec. 31, 2025

Share-Based Payment Arrangement [Abstract]

Stock-based compensation

Awards outstanding and available for issuance

During the year ended December 31, 2025, the Company had stock options outstanding under the following plans (collectively, the Arbutus Plans): the 2016 Omnibus Share and Incentive Plan (the 2016 Plan), the 2011 Omnibus Share Compensation Plan (the 2011 Plan); and the 2023 inducement grant. During the year ended December 31, 2025, the Company had restricted stock units outstanding under the 2016 Plan.

As of December 31, 2025, the aggregate number of shares authorized for awards under the Arbutus Plans was 40,493,870. As of December 31, 2025, the Company had 12,430,999 options and 1,529,959 restricted stock units outstanding and 16,881,800 awards available for issuance under the Arbutus Plans.

The Company issues new common shares of stock to settle options exercised.

The 2011 Plan expired in June 2021. Under the 2016 Plan, the Board may grant options, and other types of awards, to employees, directors and consultants of the Company. The exercise price of the options is determined by the Board but will be at least equal to the closing market price of the common shares on the date of grant and the term may not exceed 10 years. Options granted generally vest over four years for employees and for directors’ initial grants, and immediately for directors’ annual grants.

In July 2023, the Company provided an inducement grant of 500,000 options in connection with the hiring of its then-General Counsel and Chief Compliance Officer, which is governed by substantially the same terms as the 2016 Plan.

Hereafter, information on options governed by the Arbutus Plans is presented on a consolidated basis as the terms of the plans are similar.

Stock options under the Arbutus Plans

The following table summarizes activity related to the Company’s equity-classified stock options for the year ended December 31, 2025:


	Number	Weighted-Average Exercise Price
Balance as of December 31, 2024	15,451,687	$	3.37
Options granted	5,263,722	$	3.33
Options exercised	(1,926,656)	$	2.87
Options forfeited, canceled or expired	(6,357,754)	$	3.44
Balance as of December 31, 2025	12,430,999	$	3.39

The intrinsic value of options exercised under the Arbutus Plans during 2025 and 2024 was $1.8 million and $1.4 million, respectively. The weighted average grant-date fair value of stock options granted during the year ended December 31, 2025 and 2024 was $2.34 and $1.87, respectively.

The following table summarizes additional information related to the Company’s equity-classified stock options as of December 31, 2025:


	As of December 31, 2025
Options outstanding and expected to vest
Number of stock options outstanding	12,430,999
Weighted-average exercise price	$	3.39
Intrinsic value (in $000s)	$	18,345
Weighted-average term remaining	6.2 years
Vested stock options
Number of vested stock options	9,146,505
Weighted-average exercise price	$	3.44
Intrinsic value (in $000s)	$	13,243
Weighted-average term remaining	5.2 years

The assumptions used in the Black-Scholes option-pricing for grants made during the years ended December 31, 2025 and 2024 were as follows:


	December 31, 2025		December 31, 2024
Expected average option term	5.7 years		5.6 years
Expected volatility (historical)	82.2	%	92.0	%
Expected dividends	—	%	—	%
Risk-free interest rate	4.02	%	3.84	%

The Company considers all available information when estimating the fair value of its stock option grants.

Restricted Stock Units under the 2016 Plan

The following table summarizes activity related to the Company’s restricted stock units, for the year ended December 31, 2025:


	Number	Weighted-Average Grant-Date Fair Value
Balance as of December 31, 2024	1,493,136	$	2.57
Restricted stock units granted	1,968,509	$	3.58
Restricted stock units vested	(580,584)	$	2.61
Restricted stock units forfeited, canceled or expired	(1,351,102)	$	2.90
Balance as of December 31, 2025	1,529,959	$	3.55

The restricted stock units vest over three years in equal annual installments beginning one year from the grant date. The weighted average grant-date fair value of restricted stock units granted during the years ended December 31, 2025 and 2024 was $3.58 and $2.40, respectively.

Employee Stock Purchase Plan

In May 2020, the Company’s shareholders approved the 2020 Employee Stock Purchase Plan (the ESPP) which became effective on May 28, 2020. A total of 1,500,000 common shares were reserved for issuance under the ESPP. Company employees contribute funds via payroll deductions, which are used to buy Company common shares at a discount of up to 15% based on the lower of the price at the start of the offering period and at the end of the relevant purchase period within such offering period. The initial offering period under the ESPP was September 1, 2020 through August 31, 2021 with purchase dates set on February 26, 2021 and August 31, 2021, with subsequent offering periods beginning on September 1 and ending on August 31. The Company issued 60,493 and 227,333 shares under its ESPP for the years ended December 31, 2025 and 2024, respectively. As of December 31, 2025, there were 554,175 shares remaining for issuance under the ESPP. For both of the years ended December 31, 2025 and 2024, the Company recognized less than $0.1 million of stock-based compensation expense related to the ESPP. The fair value of the right to acquire stock at a discounted price under the ESPP is calculated using the Black-Scholes valuation model and recorded as stock-based compensation. Expense is recognized over the period the employee contributes to the plan through payroll deductions.

Stock-based compensation expense

Total stock-based compensation expense was comprised of the vesting of options and restricted stock units awarded to employees under the Arbutus Plans calculated in accordance with the fair value method as described above and amortization of compensation cost related to the ESPP.

The Company recognizes forfeitures as they occur, and the effects of forfeitures are reflected in stock-based compensation expense.

Stock-based compensation has been recorded in the consolidated statement of operations and comprehensive loss as follows:


	Year Ended December 31,
	2025		2024
	(in thousands)
Research and development	$	1,901	$	3,647
General and administrative	2,550		5,339
Restructuring	$	2,502	$	—
Total	$	6,953	$	8,986

At December 31, 2025, there remained $6.3 million and $4.1 million of unrecognized compensation expense related to unvested equity employee stock options and restricted stock units, respectively, to be recognized as expense over weighted-average periods of approximately 2.9 years and 1.7 years, respectively.

For each of the years ended December 31, 2025 and 2024, the Company had zero performance-based stock compensation expense.

Modification associated with restructuring

During the year ended December 31, 2025, the Company recognized $2.5 million of expense related to the modification of stock options for employees who were terminated as a result of the restructuring (Note 16). The modifications involved extension of the post-termination exercise period from 90 days to one year. The expense was recorded as part of restructuring costs in the consolidated statements of operations and comprehensive income.

Fair value measurements (Tables)

12 Months Ended

Dec. 31, 2025

Fair Value Disclosures [Abstract]

Schedule of assets and liabilities measured at fair value on a recurring basis


	Level 1		Level 2		Level 3		Total
As of December 31, 2025	(in thousands)
Assets
Cash and cash equivalents	$	18,008	$	—	$	—	$	18,008
Investments in marketable securities, current	—		73,463		—		73,463

Total	$	18,008	$	73,463	$	—	$	91,471
Liabilities
Contingent consideration	—		—		8,395		8,395
Total	$	—	$	—	$	8,395	$	8,395


	Level 1		Level 2		Level 3		Total
As of December 31, 2024	(in thousands)
Assets
Cash and cash equivalents	$	36,330	$	—	$	—	$	36,330
Investments in marketable securities, current	—		86,293		—		86,293

Total	$	36,330	$	86,293	$	—	$	122,623
Liabilities
Contingent consideration	—		—		10,225		10,225
Total	$	—	$	—	$	10,225	$	10,225

Schedule of changes in fair value of contingent consideration

The following table presents the changes in fair value of the Company’s contingent consideration:


	Liability at beginning of the period		Increase in fair value of liability		Liability at end of the period
	(in thousands)
Year ended December 31, 2025	$	10,225	$	(1,830)	$	8,395
Year ended December 31, 2024	$	7,600	$	2,625	$	10,225

Investment in Genevant	12 Months Ended
Investment in Genevant	Dec. 31, 2025
Equity Method Investments and Joint Ventures [Abstract]
Investment in Genevant	Investment in Genevant In April 2018, the Company entered into an agreement with Roivant Sciences Ltd. (Roivant), its largest shareholder, to launch Genevant Sciences Ltd., a company focused on nucleic acid- and gene editing-based therapeutics enabled by the Company’s LNP and ligand conjugate delivery technologies. The Company licensed rights to its LNP and ligand conjugate delivery platforms to Genevant outside of hepatitis B (HBV), except to the extent certain rights had already been licensed to other third parties (the Genevant License). The Company retained all rights to its LNP and conjugate delivery platforms for HBV. Under the Genevant License, as amended, if a third-party sublicensee of intellectual property licensed by Genevant from the Company commercializes a sublicensed product, the Company becomes entitled to receive a specified percentage of certain revenue that may be received by Genevant for such sublicense, including royalties, commercial milestones and other sales-related revenue, or, if less, tiered low single-digit royalties on net sales of the sublicensed product. The specified percentage is 20% in the case of a mere sublicense (i.e., naked sublicense) by Genevant without additional contribution and 14% in the case of a bona fide collaboration with Genevant. Additionally, if Genevant receives proceeds from an action for infringement by any third parties of the Company’s intellectual property licensed to Genevant, the Company would be entitled to receive, after deduction of litigation costs, 20% of the proceeds received by Genevant or, if less, tiered low single-digit royalties on net sales of the infringing product (inclusive of the proceeds from litigation or settlement, which would be treated as net sales). The Company accounts for its interest in Genevant as equity securities without readily determinable fair values. Accordingly, an estimate of the fair value of the securities is based on the original cost less previously recognized equity method losses, less impairments, plus or minus changes resulting from observable price changes in orderly transactions for identical or a similar Genevant securities. As of December 31, 2025 and 2024, the carrying value of the Company’s investment in Genevant was zero and the Company owned approximately 16% of the outstanding common equity of Genevant.

Stock-based compensation - Activity related to stock options (Details) - Arbutus Plans - Options outstanding and expected to vest - $ / shares	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Number of optioned common shares
Balance - Number of optioned common shares (in shares)	15,451,687
Options granted (in shares)	5,263,722
Options exercised (in shares)	(1,926,656)
Options forfeited, canceled or expired (in shares)	(6,357,754)
Balance - Number of optioned common shares (in shares)	12,430,999	15,451,687
Weighted average exercise price
Balance - Weighted average exercise price (in CAD and USD per share)	$ 3.37
Options granted - Weighted average exercise price (in CAD and USD per share)	3.33
Options exercised - Weighted average exercise price (in CAD and USD per share)	2.87
Options forfeited, canceled or expired - Weighted average exercise price (in CAD and USD per share)	3.44
Balance - Weighted average exercise price (in CAD and USD per share)	3.39	$ 3.37
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Weighted Average Grant Date Fair Value	$ 2.34	$ 1.87

Leases - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Leases - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Lessee, Lease, Description [Line Items]
Fixed lease payment	$ 0.2	$ 0.5
Variable lease payment	0.1	0.2
Operating Lease, Cost	$ 0.3	$ 0.7
Corporate Headquarters Located 701 Veterans Circle, Warminster, Pennsylvania
Lessee, Lease, Description [Line Items]
Discount rate	9.00%

Stock-based compensation - Valuation assumptions for stock options under the Arbutus Plan (Details) - Arbutus Plans	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected average option term	5 years 8 months 12 days	5 years 7 months 6 days
Expected volatility (historical)	82.20%	92.00%
Expected dividends	0.00%	0.00%
Risk-free interest rate	4.02%	3.84%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Leases - Maturity of lease liability (Details) $ in Thousands	Dec. 31, 2025 USD ($)
Leases [Abstract]
2026	$ 654
2027	133
2028	0
2029	0
2030	0
Thereafter	0
Total lease payments	787
Less: interest	(41)
Present value of lease payments	$ 746

Property and equipment (Details) - USD ($) $ in Thousands	12 Months Ended
Property and equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Property, Plant and Equipment [Line Items]
Cost	$ 245	$ 16,305
Accumulated depreciation	(213)	(12,996)
Net book value	32	3,309
Depreciation	363	1,380
Lab equipment
Property, Plant and Equipment [Line Items]
Cost	0	7,238
Accumulated depreciation	0	(6,105)
Net book value	0	1,133
Leasehold improvements
Property, Plant and Equipment [Line Items]
Cost	0	8,590
Accumulated depreciation	0	(6,489)
Net book value	0	2,101
Computer hardware and software
Property, Plant and Equipment [Line Items]
Cost	245	477
Accumulated depreciation	(213)	(402)
Net book value	$ 32	$ 75

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2025
Audit Information [Abstract]
Auditor Name	Ernst & Young LLP
Auditor Location	Philadelphia, Pennsylvania
Auditor Firm ID	42

Sale of future royalties - Narrative (Details) - USD ($)			12 Months Ended		78 Months Ended
	Jul. 02, 2019	Jan. 01, 2019	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2025
Other Liabilities Disclosure [Line Items]
Non-cash royalty revenue			$ 1,482,000	$ 2,251,000
Non-cash interest expense			$ 95,000	127,000
Minimum
Other Liabilities Disclosure [Line Items]
Royalty interest, Percent interest			75.00%
Maximum
Other Liabilities Disclosure [Line Items]
Royalty interest, Percent interest			112.50%
OMERS
Other Liabilities Disclosure [Line Items]
Royalty interest sold, percentage of sales, annual revenue threshold of highest tier	$ 500,000,000
Gross proceeds from royalty interest sold		$ 20,000,000
Royalty interest sold, maximum royalties for buyer	$ 30,000,000
Royalty guarantees commitments percentage	100.00%
Royalty payable	$ 30,000,000.0
Non-cash royalty revenue			$ 1,500,000	2,300,000	$ (26,500,000)
Transaction costs related to sale of future royalties	$ 1,500,000
Effective annual interest rate of royalty liability			2.10%
Non-cash interest expense			$ 100,000	$ 100,000
OMERS \| Minimum
Other Liabilities Disclosure [Line Items]
Royalty, percentage of interest sold	1.00%
Royalty interest, Percent interest			0.75%
OMERS \| Maximum
Other Liabilities Disclosure [Line Items]
Royalty, percentage of interest sold	2.33%
Royalty interest, Percent interest			1.125%

Stock-based compensation - Stock-based compensation expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 6,953	$ 8,986
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,901	3,647
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	2,550	5,339
Restructuring
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 2,502	$ 0

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Consolidated Balance Sheets (Parenthetical) - shares	12 Months Ended
Consolidated Balance Sheets (Parenthetical) - shares	Dec. 31, 2025	Dec. 31, 2024
Statement of Financial Position [Abstract]
Common shares, shares issued (in shares)	192,531,225	189,963,492
Common shares, shares outstanding (in shares)	192,531,225	189,963,492
Common Stock, Shares Authorized, Unlimited [Fixed List]	Unlimited

Accounts payable and accrued liabilities

12 Months Ended

Dec. 31, 2025

Payables and Accruals [Abstract]

Accounts payable and accrued liabilities

Accounts payable and accrued liabilities were comprised of the following:


	December 31, 2025		December 31, 2024
	(in thousands)
Trade accounts payable	$	1,173	$	2,316
Payroll accruals	2,159		3,393
Research and development accruals	412		691
Professional fee accruals	1,075		1,164
Restructuring liabilities	640		—
Total	$	5,459	$	7,564

In March 2025, the Company implemented changes to focus its efforts on advancing the clinical development of imdusiran and AB-101 by ceasing all discovery efforts, implementing workforce reductions, and halting preparations for a potential IM-PROVE III clinical trial. In addition, in 2025, the decision was made to exit the Company’s corporate headquarters in Warminster, Pennsylvania and to discontinue in-house scientific research. The Company recognized $12.9 million of restructuring charges in 2025, of which there was $0.6 million in severance and medical benefit costs and lease expenses accrued as of December 31, 2025.

Income taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Income taxes - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Components of Deferred Tax Assets [Line Items]
Canadian federal and provincial income tax rate	25.00%
Research and development credits	$ 8,700	$ 8,300
Operating loss carryforwards	111,292	96,075
Deferred tax assets, operating loss carryforwards, subject to expiration	11,700	11,700
Domestic	11,952	(1,671)
Foreign	(45,453)	(68,249)
U.S. research and experimental expenditures capitalization	27,188	33,707
Federal
Components of Deferred Tax Assets [Line Items]
Net operating losses	329,900	260,000
Investment tax credit carryforward
Components of Deferred Tax Assets [Line Items]
Investment tax credits available to reduce Canadian federal income taxes	7,100	7,100
Investment tax credits available to reduce provincial income taxes	2,000	2,000
Research tax credit carryforward
Components of Deferred Tax Assets [Line Items]
Operating loss carryforwards	61,800	61,800
General Business Tax Credit Carryforward
Components of Deferred Tax Assets [Line Items]
Deferred tax assets, operating loss carryforwards, subject to expiration	$ 152,700	$ 150,800

Leases

12 Months Ended

Dec. 31, 2025

Leases [Abstract]

Leases

In the first quarter of 2025, the Board decided to exit our corporate headquarters at 701 Veterans Circle, Warminster, Pennsylvania. The lease for this property expires on April 30, 2027 and was the Company’s sole operating lease as of December 31, 2025.

The Company accounts for its lease under ASC 842, Leases. Leases with an initial term of 12 months or less are not recorded on the balance sheet. The Company determines if an arrangement is a lease at inception. Right-of-use assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease right-of-use assets and lease liabilities are recognized based on the present value of lease payments over the lease term. The lease does not provide an implicit rate so in determining the present value of lease payments, the Company utilized its incremental borrowing rate for the lease, which was 9.0%. The Company recognizes lease expense on a straight-line basis over the remaining lease term.

During the years ended December 31, 2025 and 2024, the Company incurred total operating lease expenses of $0.3 million and $0.7 million, respectively, which included lease expenses associated with fixed lease payments of $0.2 million and $0.5 million, respectively, and variable payments associated with common area maintenance and similar expenses of $0.1 million and $0.2 million, respectively.

Weighted average remaining lease term and discount rate were as follows:


			As of December 31, 2025
Weighted-average remaining lease term (years)			1.3
Weighted average discount rate			9.0%

The Company did not include options to extend its lease terms as part of its ROU asset and lease liabilities.

Supplemental cash flow information related to the Company’s operating lease was as follows:


	Twelve Months Ended December 31,
	2025		2024
	(in thousands)
Cash paid for amounts included in the measurement of lease liabilities	$	634	$	616

Future minimum lease payments under the Company’s operating lease as of December 31, 2025 were as follows:


	As of December 31, 2025
	(in thousands)
2026	$	654
2027	133
2028	—
2029	—
2030	—
Thereafter	—
Total lease payments	$	787
Less: interest	(41)
Present value of lease payments	$	746

Income taxes

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Income taxes

The Company is subject to taxation and files income tax returns in Canadian federal and provincial, and United States federal and several state jurisdictions. As described in Note 2, the Company implemented ASU 2023-09 for the year ended December 31, 2025 on a prospective basis.

Income tax expense varies from the amounts that would be computed by applying the combined Canadian federal tax rate of 25% to the loss before income taxes as shown in the following tables. The change in the rate from 27% in 2024 to 25% in 2025 is due to the adoption of the new standard, which requires the rate reconciliation to begin with the federal rate in the country of domicile. In 2024, a combined rate of 27% was used (federal of 15% and provincial of 12%).

The domestic and foreign components of loss before income taxes were as follows:


	Year ended December 31,
	2025		2024
	(in thousands)
Domestic	$	11,952	$	(1,671)
Foreign	$	(45,453)	$	(68,249)
Loss before income taxes	$	(33,501)	$	(69,920)

There is no provision for federal, state or foreign income taxes.

A reconciliation of the Canadian federal statutory income tax rate to the effective tax rate for the year ended December 31, 2025 in accordance with the guidance in ASU 2023-09 is as follows:


	Year Ended December 31, 2025
	(in thousands, except percentages)
Computed taxes (benefits) at Canadian federal rates	$	(8,374)	25	%
Domestic tax effects:
Change in valuation allowance	(2,540)		8	%
Other	(449)		1	%
Domestic provincial tax effects:
Tax abatement	(1,195)		4	%
Provincial tax	1,435		(4)	%
Change in valuation allowance	(203)		1	%
Other	(36)		—	%
Foreign tax effects:
United States
Foreign tax rate differential	1,818		(5)	%
Non-taxable and non-deductible items: stock options	879		(3)	%
Tax credits: research and development credits	(403)		1	%
Changes in valuation allowance	8,706		(26)	%
Other adjustments:
Stock option adjustment	304		(1)	%
Other	58		—	%
Effective tax rate	$	—	—	%

The reconciliation of the combined Canadian federal and provincial income tax rate to the effective income tax rate for the year ended December 31, 2024 is as follows:


	Year Ended December 31, 2024
	(in thousands)
Computed taxes (benefits) at Canadian federal and provincial tax rates	$	(18,888)

Permanent and other differences	515
Federal R&D credit	(1,122)


Change in valuation allowance	11,748
Difference due to income taxed at foreign rates	4,101
Stock-based compensation	1,327
Other	2,319
Income tax expense	$	—

The Company had investment tax credits available to reduce Canadian federal income taxes of $7.1 million as of both December 31, 2025 and 2024, which expire between 2031 and 2037, and provincial income taxes of $2.0 million as of both December 31, 2025 and 2024, which expire between 2024 and 2027. The investment tax credits are accounted for under a flow-through method. In addition, the Company had research and development credits of $8.7 million as of December 31, 2025 and $8.3 million as of December 31, 2024, which expire between 2031 and 2038 and which can be used to reduce future taxable income in the United States.

The Company had scientific research and experimental development expenditures of $61.8 million available for indefinite carry-forward as of both December 31, 2025 and 2024. The Company also had net operating losses of $152.7 million and $150.8 million as of December 31, 2025 and 2024, respectively, which are due to expire between 2035 and 2038 and which can be used to offset future taxable income in Canada.

As of December 31, 2025 and 2024, the Company had $11.7 million of net operating losses due to expire in 2035 which can be used to offset future taxable income in the United States. United States net operating loss carryforwards arising in 2019 and future periods have an indefinite carryforward period. As of December 31, 2025 and 2024, the Company had $329.9 million and $260.0 million of net operating losses subject to an indefinite carryforward period which can be used to offset future taxable income in the United States.

As a result of ownership changes occurring on October 1, 2014 and March 4, 2015, the Company’s ability to use these losses may be limited under Internal Revenue Code Section 382. Losses incurred to date may be further limited if a subsequent change in control occurs.

The Company generated $12.0 million of pre-tax domestic income and $45.5 million in pre-tax foreign losses, respectively, for the year ended December 31, 2025. The Company generated $1.7 million of pre-tax domestic losses and $68.2 million in pre-tax foreign losses, respectively, for the year ended December 31, 2024. The Company used accumulated domestic net operating losses to offset the taxable income in both years.

As required by the 2017 Tax Cuts and Jobs Act and effective in 2022, the deferred tax asset as of December 31, 2025 and 2024 included $27.2 million and $33.7 million, respectively, related to the mandatory capitalization and amortization of research and development expenses.

Significant components of the Company’s deferred tax assets and liabilities are shown below:


	As of December 31,
	2025		2024
	(in thousands)
Deferred tax assets (liabilities):
Operating loss carryforwards	$	111,292	$	96,075
Canadian research and development deductions	16,673		16,700
Book amortization in excess of tax	308		(232)
Revenue recognized for tax purposes in excess of revenue recognized for accounting purposes	929		1,296
Tax value in excess of accounting value in lease inducements	157		51
Deferred revenue	—		2,817
Canadian Federal investment tax credits	5,147		5,147
Canadian Provincial investment tax credits	1,953		1,953
Equity method investment	3,375		3,375
U.S. Federal research and development credits	8,677		8,310
Deductible stock options	3,559		4,037
U.S. research and experimental expenditures capitalization	27,188		33,707
Accrued interest payable	1,869		1,796
Amortization	191		256
Other	72		138
Total deferred tax assets	$	181,390	$	175,426
Valuation allowance	(181,390)		(175,426)
Net deferred tax assets (liabilities)	$	—	$	—

- Definition

The entire disclosure for income tax.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
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-Name Accounting Standards Codification
-Section 50
-Paragraph 1
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-URI https://asc.fasb.org/1943274/2147477617/942-740-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479360/740-10-S99-2

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482603/740-30-50-2

+ Details

Collaborations and royalty entitlements - Narrative (Details)					12 Months Ended		78 Months Ended
	Jan. 06, 2022 USD ($)	Jan. 05, 2022 USD ($)	Jul. 02, 2019 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2025 USD ($) product shares	Dec. 31, 2024 USD ($) shares	Dec. 31, 2025 USD ($) product shares	Jun. 30, 2025 $ / shares	Dec. 13, 2021 USD ($) $ / shares shares	Apr. 11, 2018
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Common shares, shares issued (in shares) \| shares					192,531,225	189,963,492	192,531,225
Shares price (in USD per share) \| $ / shares								$ 3.09
Total revenue					$ 14,083,000	$ 6,171,000
Deferred license revenue, current					0	7,571,000	$ 0
Deferred license revenue, non-current					$ 0	2,863,000	$ 0
Number of royalty entitlements \| product					2		2
Non-cash royalty revenue					$ 1,482,000	2,251,000
License
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Equity method investment, percentage or revenue entitled										50.00%
Non-cash royalty revenue
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total revenue					$ 1,482,000	2,252,000
Minimum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Royalty interest, Percent interest					75.00%
Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Royalty interest, Percent interest					112.50%
Common Shares \| Qilu
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Ownership interest (percent)									2.50%
Qilu
Research and Development Arrangement, Contract to Perform for Others [Line Items]
License Agreement Milestone payment maximum									$ 245,000,000
Qilu \| Common Shares
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Common shares, shares issued (in shares) \| shares									3,579,952
Shares price (in USD per share) \| $ / shares									$ 4.19
Premium percentage on closing stock price									15.00%
Proceeds from issuance of common stock	$ 15,000,000.0
Qilu \| One-Time Upfront Cash Payment
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Cash payment for collaborations		$ 40,000,000.0
Barinthus
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Percent of costs related to collaboration					50.00%
Costs related to collaboration					$ 1,400,000	2,100,000
OMERS
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Royalty interest sold, percentage of sales, annual revenue threshold of highest tier			$ 500,000,000
Gross proceeds from royalty interest sold				$ 20,000,000
Royalty interest sold, maximum royalties for buyer			$ 30,000,000
Royalty guarantees commitments percentage			100.00%
Royalty payable			$ 30,000,000.0
Non-cash royalty revenue					$ 1,500,000	2,300,000	$ (26,500,000)
OMERS \| Minimum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Royalty, percentage of interest sold			1.00%
Royalty interest, Percent interest					0.75%
OMERS \| Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Royalty, percentage of interest sold			2.33%
Royalty interest, Percent interest					1.125%
Royalties from sales of ONPATTRO \| License
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total revenue					$ 1,667,000	2,562,000
Qilu Pharmaceutical Co., Ltd.
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Income taxes paid					4,400,000
Revenue, remaining performance obligation, amount									$ 50,400,000
Premiums earned, net					4,100,000
Other deferred costs, gross					600,000		$ 600,000
Amortization of other deferred charges					200,000	100,000
Qilu Pharmaceutical Co., Ltd. \| License
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total revenue					10,434,000	1,357,000
Deferred Income, Revenue Recognized					9,600,000
Qilu Pharmaceutical Co., Ltd. \| Service, Other
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Deferred Income, Revenue Recognized					800,000
Qilu Pharmaceutical Co., Ltd. \| One-Time Upfront Cash Payment
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Cash payment for collaborations					40,000,000.0
Royalties from sales of ONPATTRO \| Non-cash royalty revenue
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total revenue					1,482,000	$ 2,252,000
ONPATTRO, global net sales
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Annual Revenue Threshold					$ 500,000,000

Stock-based compensation (Tables)

12 Months Ended

Dec. 31, 2025

Share-Based Payment Arrangement [Abstract]

Schedule of stock option activity

The following table summarizes activity related to the Company’s equity-classified stock options for the year ended December 31, 2025:


	Number	Weighted-Average Exercise Price
Balance as of December 31, 2024	15,451,687	$	3.37
Options granted	5,263,722	$	3.33
Options exercised	(1,926,656)	$	2.87
Options forfeited, canceled or expired	(6,357,754)	$	3.44
Balance as of December 31, 2025	12,430,999	$	3.39

The following table summarizes additional information related to the Company’s equity-classified stock options as of December 31, 2025:


	As of December 31, 2025
Options outstanding and expected to vest
Number of stock options outstanding	12,430,999
Weighted-average exercise price	$	3.39
Intrinsic value (in $000s)	$	18,345
Weighted-average term remaining	6.2 years
Vested stock options
Number of vested stock options	9,146,505
Weighted-average exercise price	$	3.44
Intrinsic value (in $000s)	$	13,243
Weighted-average term remaining	5.2 years

The following table summarizes activity related to the Company’s restricted stock units, for the year ended December 31, 2025:


	Number	Weighted-Average Grant-Date Fair Value
Balance as of December 31, 2024	1,493,136	$	2.57
Restricted stock units granted	1,968,509	$	3.58
Restricted stock units vested	(580,584)	$	2.61
Restricted stock units forfeited, canceled or expired	(1,351,102)	$	2.90
Balance as of December 31, 2025	1,529,959	$	3.55

Schedule of weighted average Black-Scholes option-pricing assumptions and resultant fair values

The assumptions used in the Black-Scholes option-pricing for grants made during the years ended December 31, 2025 and 2024 were as follows:


	December 31, 2025		December 31, 2024
Expected average option term	5.7 years		5.6 years
Expected volatility (historical)	82.2	%	92.0	%
Expected dividends	—	%	—	%
Risk-free interest rate	4.02	%	3.84	%

Schedule of allocation of stock-based compensation

Stock-based compensation has been recorded in the consolidated statement of operations and comprehensive loss as follows:


	Year Ended December 31,
	2025		2024
	(in thousands)
Research and development	$	1,901	$	3,647
General and administrative	2,550		5,339
Restructuring	$	2,502	$	—
Total	$	6,953	$	8,986

Property and equipment (Tables)

12 Months Ended

Dec. 31, 2025

Property, Plant and Equipment [Abstract]

Schedule of property and equipment

The Company’s property and equipment balances as of the years ended December 31, 2025 and 2024 were as follows:


	Cost		Accumulated depreciation		Net book value
December 31, 2025	(in thousands)
Lab equipment	$	—	$	—	$	—
Leasehold improvements	—		—		—
Computer hardware and software	245		(213)		32
	$	245	$	(213)	$	32


	Cost		Accumulated depreciation		Net book value
December 31, 2024	(in thousands)
Lab equipment	$	7,238	$	(6,105)	$	1,133
Leasehold improvements	8,590		(6,489)		2,101
Computer hardware and software	477		(402)		75
	$	16,305	$	(12,996)	$	3,309

Income taxes - Deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Components of Deferred Tax Assets [Line Items]
Operating loss carryforwards	$ 111,292	$ 96,075
Canadian research and development deductions	16,673	16,700
Book amortization in excess of tax	308	(232)
Revenue recognized for tax purposes in excess of revenue recognized for accounting purposes	929	1,296
Tax value in excess of accounting value in lease inducements	157	51
Equity method investment	3,375	3,375
U.S. Federal research and development credits	8,677	8,310
Deductible stock options	3,559	4,037
U.S. research and experimental expenditures capitalization	27,188	33,707
Accrued interest payable	1,869	1,796
Amortization	191	256
Other	72	138
Total deferred tax assets	181,390	175,426
Valuation allowance	(181,390)	(175,426)
Net deferred tax assets (liabilities)	0	0
Qilu Pharmaceutical Co., Ltd.
Components of Deferred Tax Assets [Line Items]
Deferred revenue	0	2,817
Federal
Components of Deferred Tax Assets [Line Items]
Investment tax credits	5,147	5,147
Domestic tax effects:
Components of Deferred Tax Assets [Line Items]
Investment tax credits	$ 1,953	$ 1,953

Contingencies and commitments (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Oct. 31, 2014
Contingencies and Commitments [Line Items]
Contingent consideration	$ 8,395	$ 10,225	$ 7,600
Fair Value, Measurements, Recurring \| Enantigen's Selling Shareholders
Contingencies and Commitments [Line Items]
Contingent consideration	8,400
Blumberg and Drexel \| Fair Value, Measurements, Recurring \| Enantigen
Contingencies and Commitments [Line Items]
Contingent consideration	$ 0
Blumberg and Drexel \| Arbutus Inc.
Contingencies and Commitments [Line Items]
Development and regulatory milestones payment per licensed compound series, maximum				$ 102,500
Maximum royalty payment				$ 1,000

Investments in marketable securities

12 Months Ended

Dec. 31, 2025

Investments, Debt and Equity Securities [Abstract]

Investments in marketable securities

Investments in marketable securities and cash equivalents consisted of the following:


	Amortized Cost		Gross Unrealized Gain(1)		Gross Unrealized Loss(1)		Fair Value
As of December 31, 2025	(in thousands)
Cash equivalents
Money market funds	$	10,218	$	—	$	—	$	10,218
Total	$	10,218	$	—	$	—	$	10,218
Investments in marketable short-term securities


US treasury bills	$	37,411	$	41	$	—	$	37,452
US government bonds	35,965		46		—		36,011
Total	$	73,376	$	87	$	—	$	73,463

(1) Gross unrealized gain (loss) is pre-tax and is reported in accumulated other comprehensive loss.


	Amortized Cost		Gross Unrealized Gain(1)		Gross Unrealized Loss(1)		Fair Value
As of December 31, 2024	(in thousands)
Cash equivalents
Money market fund	$	29,533	$	—	$	—	$	29,533
Total	$	29,533	$	—	$	—	$	29,533
Investments in marketable short-term securities

US corporate bonds	$	30,776	$	27	$	(6)	$	30,797

US treasury bills	55,467		29				55,496

Total	$	86,243	$	56	$	(6)	$	86,293

(1) Gross unrealized gain (loss) is pre-tax and is reported in accumulated other comprehensive loss.

The contractual maturity of the $73.5 million and $86.3 million of short-term marketable securities held by the Company as of December 31, 2025 and December 31, 2024, respectively, was less than one year. As of December 31, 2025 and December 31, 2024, the Company did not hold any long-term marketable securities.

At December 31, 2025, the Company had no available-for-sale investment debt securities in an unrealized loss position. At December 31, 2024, the Company had 6 available-for-sale investment debt securities in an unrealized loss position without an allowance for credit losses. Unrealized losses on the Company’s investments in debt securities have not been recognized into income as the issuers’ bonds are of high credit quality and the decline in fair value is largely due to market conditions and/or changes in interest rates. The Company does not intend to sell and it is more likely than not that the Company will not be required to sell the securities prior to the anticipated recovery of their amortized cost basis. The issuers continue to make timely interest payments on the bonds. The fair value is expected to recover as the bonds approach maturity.

Accrued interest receivable on investments in marketable securities was $0.3 million at both December 31, 2025 and 2024 and is included in prepaid expenses and other current assets.

The Company had realized gains on investments of less than $0.1 million for both of the years ended December 31, 2025 and 2024

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
Consolidated Statements of Cash Flows - USD ($)	Dec. 31, 2025	Dec. 31, 2024
OPERATING ACTIVITIES
Net loss	$ (33,501,000)	$ (69,920,000)
Non-cash items:
Depreciation and amortization	363,000	1,380,000
Gain on sale of property and equipment	(674,000)	0
Stock-based compensation expense	6,953,000	8,986,000
Change in fair value of contingent consideration	(1,830,000)	2,625,000
Non-cash royalty revenue	(1,482,000)	(2,251,000)
Non-cash interest expense	95,000	127,000
Restructuring, Settlement and Impairment Provisions	2,811,000	167,000
Net accretion of investments in marketable securities	(2,349,000)	(3,135,000)
Net change in operating items:
Accounts receivable	1,375,000	(633,000)
Prepaid expenses and other assets	1,698,000	2,298,000
Accounts payable and accrued liabilities	(2,105,000)	(2,707,000)
Change in deferred license revenue	(10,434,000)	(1,357,000)
Other liabilities	(557,000)	(430,000)
Net cash used in operating activities	(39,637,000)	(64,850,000)
INVESTING ACTIVITIES
Purchase of investments in marketable securities	(140,061,000)	(141,509,000)
Disposition of investments in marketable securities	155,277,000	164,639,000
Proceeds from sale of property and equipment	364,000	0
Acquisition of property and equipment	0	(182,000)
Net cash provided by investing activities	15,580,000	22,948,000
FINANCING ACTIVITIES
Issuance of common shares pursuant to the Open Market Sale Agreement	0	44,123,000
Issuance of common shares pursuant to exercise of stock options	5,540,000	7,477,000
Issuance of common shares pursuant to ESPP	181,000	396,000
Net cash provided by financing activities	5,721,000	51,996,000
Effect of foreign exchange rate changes on cash and cash equivalents	14,000	(49,000)
(Decrease) / increase in cash and cash equivalents	(18,322,000)	10,045,000
Cash and cash equivalents, beginning of period	36,330,000	26,285,000
Cash and cash equivalents, end of period	$ 18,008,000	$ 36,330,000

Consolidated Statement of Stockholders’ Equity - USD ($) $ in Thousands	Total	Common Shares	Additional paid-in capital	Deficit	Accumulated other comprehensive loss
Shares, Issued, Beginning Balance at Dec. 31, 2023		169,867,414
Beginning balance at Dec. 31, 2023	$ 106,018	$ 1,349,821	$ 81,270	$ (1,276,652)	$ (48,421)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	8,986		8,986
Issuance of common shares pursuant to the Open Market Sales Agreement (in shares)		16,499,999
Issuance of common shares pursuant to the Open Market Sale Agreement	$ 44,123	$ 44,123
Issuance of common shares pursuant to exercise of ESPP options (in shares)	227,333	227,333
Issuance of common shares pursuant to exercise of ESPP	$ 396	$ 536	(140)
Issuance of common shares pursuant to exercise of options (in shares)		2,958,264
Issuance of common shares pursuant to exercise of stock options	7,477	$ 14,355	(6,878)
Issuance of common shares upon settlement of RSUs (in shares)		410,482
Issuance of common shares upon settlement of RSUs	0	$ 1,190	(1,190)
Unrealized gain (loss) on available-for-sale securities	286				286
Net loss	(69,920)			(69,920)
Ending balance (in shares) at Dec. 31, 2024		189,963,492
Ending balance at Dec. 31, 2024	97,366	$ 1,410,025	82,048	(1,346,572)	(48,135)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	$ 6,953		6,953
Issuance of common shares pursuant to exercise of ESPP options (in shares)	60,493	60,493
Issuance of common shares pursuant to exercise of ESPP	$ 181	$ 252	(71)
Issuance of common shares pursuant to exercise of options (in shares)		1,926,656
Issuance of common shares pursuant to exercise of stock options	5,540	$ 9,634	(4,094)
Issuance of common shares upon settlement of RSUs (in shares)		580,584
Issuance of common shares upon settlement of RSUs	0	$ 1,518	(1,518)
Unrealized gain (loss) on available-for-sale securities	37				37
Net loss	(33,501)			(33,501)
Ending balance (in shares) at Dec. 31, 2025		192,531,225
Ending balance at Dec. 31, 2025	$ 76,576	$ 1,421,429	$ 83,318	$ (1,380,073)	$ (48,098)

Income taxes - Income Tax Rate Reconciliation, Post ASU 2023-09 Update (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Amount
Computed taxes (benefits) at Canadian federal and provincial tax rates	$ (8,374)	$ (18,888)
Change in valuation allowance		11,748
Foreign tax rate differential		4,101
Non-taxable and non-deductible items: stock options	304	1,327
Tax credits: research and development credits		(1,122)
Other	58
Income tax expense	$ 0	$ 0
Percent
Canadian federal and provincial income tax rate	25.00%
Non-taxable and non-deductible items: stock options	(1.00%)
Other	0.00%
Effective tax rate	0.00%
Domestic tax effects:
Amount
Change in valuation allowance	$ (2,540)
Other	$ (449)
Percent
Change in valuation allowance	8.00%
Other	1.00%
Domestic provincial tax effects:
Amount
Change in valuation allowance	$ (203)
Tax abatement	(1,195)
Provincial tax	1,435
Other	$ (36)
Percent
Change in valuation allowance	1.00%
Tax abatement	0.04
Provincial tax	(4.00%)
Other	0.00%
United States
Amount
Change in valuation allowance	$ 8,706
Foreign tax rate differential	1,818
Non-taxable and non-deductible items: stock options	879
Tax credits: research and development credits	$ (403)
Percent
Change in valuation allowance	(26.00%)
Foreign tax rate differential	(5.00%)
Non-taxable and non-deductible items: stock options	(3.00%)
Tax credits: research and development credits	1.00%

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Current assets:
Cash and cash equivalents	$ 18,008	$ 36,330
Investments in marketable securities, current	73,463	86,293
Accounts receivable	1,447	2,409
Prepaid expenses and other current assets	1,538	2,284
Total current assets	94,456	127,316
Property and equipment, net of accumulated depreciation and impairment	32	3,309
Investments in marketable securities, non-current	0	0
Right of use asset	0	1,048
Other non-current assets	130	34
Total assets	94,618	131,707
Current liabilities:
Accounts payable and accrued liabilities	5,459	7,564
Deferred license revenue, current	0	7,571
Lease liability, current	547	483
Total current liabilities	6,006	15,618
Liability related to sale of future royalties	3,442	4,829
Deferred license revenue, non-current	0	2,863
Contingent consideration	8,395	10,225
Lease liability, non-current	199	806
Total liabilities	18,042	34,341
Stockholders’ equity
Issued and outstanding: 192,531,225 and 189,963,492 as of December 31, 2025 and 2024, respectively.	1,421,429	1,410,025
Additional paid-in capital	83,318	82,048
Deficit	(1,380,073)	(1,346,572)
Accumulated other comprehensive loss	(48,098)	(48,135)
Total stockholders' equity	76,576	97,366
Total liabilities and stockholders' equity	$ 94,618	$ 131,707

Cybersecurity Risk Management and Strategy Disclosure	12 Months Ended
Cybersecurity Risk Management and Strategy Disclosure	Dec. 31, 2025
Cybersecurity Risk Management, Strategy, and Governance [Line Items]
Cybersecurity Risk Management Processes for Assessing, Identifying, and Managing Threats [Text Block]	We are increasingly dependent on sophisticated software applications and computing infrastructure to conduct key operations. We depend on both our own systems, networks, and technology as well as the systems, networks and technology of our contractors, consultants, vendors and other business partners. Cybersecurity Program Given the importance of cybersecurity to our business, we maintain a robust and comprehensive cybersecurity program to support both the effectiveness of our systems and our preparedness for information security risks. This program includes a number of administrative, physical and technical safeguards, with regular evaluations of our cybersecurity posture, including internal and external audits, as well as annual penetration tests. We also require cybersecurity training when onboarding new employees and contractors and on an annual basis thereafter. Our cybersecurity program leverages industry frameworks, including the National Institute of Standards and Technology (NIST) Cybersecurity Framework to strengthen our program effectiveness and reduce cybersecurity risks. We use a risk-based approach with respect to our oversight of third-party service providers. As part of our process for onboarding new vendors, we assess new third-party service providers for technical capabilities, reputation, financial stability, pricing, and other criteria and such third-party service providers are reviewed and approved by our Finance and Legal departments. We have implemented processes to confirm that agreements with third-parties contain data security and privacy terms as appropriate. For certain key third-party service providers, we obtain a SOC type 2 audit report from the vendor’s audit firm which provides detailed information and assurance about a service organization’s security, availability, processing integrity, confidentiality and privacy controls. Process for Assessing, Identifying and Managing Material Risks from Cybersecurity Threats In the event of a cybersecurity incident, we maintain a regularly tested Incident Management and Response program as well as business continuity and disaster recovery plans. Pursuant to the program and its escalation protocols, designated personnel are responsible for assessing the severity of an incident and associated threat and handling it in accordance with that severity level. We have relationships with a number of third-party service providers to assist with cybersecurity evaluation, containment and remediation efforts.
Cybersecurity Risk Management Processes Integrated [Flag]	true
Cybersecurity Risk Management Processes Integrated [Text Block]	Given the importance of cybersecurity to our business, we maintain a robust and comprehensive cybersecurity program to support both the effectiveness of our systems and our preparedness for information security risks.
Cybersecurity Risk Management Third Party Engaged [Flag]	true
Cybersecurity Risk Third Party Oversight and Identification Processes [Flag]	true
Cybersecurity Risk Materially Affected or Reasonably Likely to Materially Affect Registrant [Flag]	false
Cybersecurity Risk Board of Directors Oversight [Text Block]	Board Oversight While our Board of Directors has overall responsibility for risk oversight, our Audit Committee oversees cybersecurity risk matters. The Audit Committee is responsible for reviewing, discussing with management, and overseeing our data privacy, information technology and security and cybersecurity risk exposures. On at least an annual basis, the ED, IT & IS reports to the Audit Committee on information security and cybersecurity matters, including significant information technology risks, significant threats (and the potential impact of those exposures on our business, financial results, operations and reputation) and the steps implemented by management to monitor and mitigate exposures. He also apprises the Audit Committee promptly of high priority cybersecurity incidents, consistent with our Incident Management and Response Policy, and provides updates to the full Board as needed.
Cybersecurity Risk Board Committee or Subcommittee Responsible for Oversight [Text Block]	The controls and processes employed to assess, identify and manage material risks from cybersecurity threats are implemented and overseen by our Executive Director of IT and Information Security (ED, IT & IS), who reports to our Chief Financial Officer
Cybersecurity Risk Process for Informing Board Committee or Subcommittee Responsible for Oversight [Text Block]	He is responsible for the day-to-day management of the cybersecurity program, including the prevention, detection, investigation, response to, and recovery from cybersecurity threats and incidents, and is regularly engaged to help ensure the cybersecurity program functions effectively in the face of evolving cybersecurity threats. He provides regular briefings (quarterly at a minimum) to our Computer Security Incident Response Team consisting of the Chief Financial Officer and General Counsel/Chief Compliance Officer on cybersecurity matters, including threats, events, and program enhancements.
Cybersecurity Risk Role of Management [Text Block]	Management Oversight The controls and processes employed to assess, identify and manage material risks from cybersecurity threats are implemented and overseen by our Executive Director of IT and Information Security (ED, IT & IS), who reports to our Chief Financial Officer. Our ED, IT & IS has over 30 years of IT experience and an Advanced Graduate Certification in Cybersecurity. He is responsible for the day-to-day management of the cybersecurity program, including the prevention, detection, investigation, response to, and recovery from cybersecurity threats and incidents, and is regularly engaged to help ensure the cybersecurity program functions effectively in the face of evolving cybersecurity threats. He provides regular briefings (quarterly at a minimum) to our Computer Security Incident Response Team consisting of the Chief Financial Officer and General Counsel/Chief Compliance Officer on cybersecurity matters, including threats, events, and program enhancements.
Cybersecurity Risk Management Positions or Committees Responsible [Flag]	true
Cybersecurity Risk Management Positions or Committees Responsible [Text Block]	Executive Director of IT and Information Security (ED, IT & IS), who reports to our Chief Financial Officer
Cybersecurity Risk Management Expertise of Management Responsible [Text Block]	Our ED, IT & IS has over 30 years of IT experience and an Advanced Graduate Certification in Cybersecurity.
Cybersecurity Risk Process for Informing Management or Committees Responsible [Text Block]	The controls and processes employed to assess, identify and manage material risks from cybersecurity threats are implemented and overseen by our Executive Director of IT and Information Security (ED, IT & IS), who reports to our Chief Financial Officer. Our ED, IT & IS has over 30 years of IT experience and an Advanced Graduate Certification in Cybersecurity. He is responsible for the day-to-day management of the cybersecurity program, including the prevention, detection, investigation, response to, and recovery from cybersecurity threats and incidents, and is regularly engaged to help ensure the cybersecurity program functions effectively in the face of evolving cybersecurity threats. He provides regular briefings (quarterly at a minimum) to our Computer Security Incident Response Team consisting of the Chief Financial Officer and General Counsel/Chief Compliance Officer on cybersecurity matters, including threats, events, and program enhancements.
Cybersecurity Risk Management Positions or Committees Responsible Report to Board [Flag]	true

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Dec. 31, 2025
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Collaborations and royalty entitlements

12 Months Ended

Dec. 31, 2025

Revenue from Contract with Customer [Abstract]

Collaborations and royalty entitlements

Collaborations

Qilu Pharmaceuticals Co, Ltd.

In December 2021, the Company entered into a technology transfer and license agreement (the Qilu License Agreement) with Qilu Pharmaceutical Co., Ltd. (Qilu), pursuant to which the Company granted Qilu a sublicensable, royalty-bearing license, under certain intellectual property owned by the Company, which was non-exclusive as to development and manufacturing and exclusive with respect to commercialization of imdusiran, including pharmaceutical products that include imdusiran, for the treatment or prevention of hepatitis B in China, Hong Kong, Macau and Taiwan (Greater China and Taiwan).

In partial consideration for the rights granted by the Company, Qilu paid the Company a one-time upfront cash payment of $40.0 million on January 5, 2022 and agreed to pay the Company up to $245 million, net of withholding taxes, upon the achievement of certain technology transfer, development, regulatory and commercialization milestones (the Milestone Payments). Qilu paid $4.4 million of withholding taxes to the Chinese taxing authority on the Company’s behalf, related to the upfront cash payment. In addition, Qilu agreed to pay the Company double-digit royalties into the low twenties percent based upon annual net sales of imdusiran in Greater China and Taiwan. The royalties were payable on a product-by-product and region-by-region basis, subject to certain limitations.

Qilu was responsible for all costs related to developing, obtaining regulatory approval for, and commercializing imdusiran for the treatment or prevention of hepatitis B in Greater China and Taiwan. Qilu was required to use commercially reasonable efforts to develop, seek regulatory approval for, and commercialize at least one imdusiran product candidate in Greater China and Taiwan. A joint development committee was established between the Company and Qilu to coordinate and review the development, manufacturing and commercialization plans. Both parties also entered into a supply agreement and related quality agreement pursuant to which the Company would manufacture and supply Qilu with all quantities of imdusiran necessary for Qilu to develop and commercialize in Greater China and Taiwan until the Company completed its manufacturing technology transfer to Qilu and Qilu received all approvals required for it or its designated contract manufacturing organization to manufacture imdusiran in Greater China and Taiwan.

Concurrent with the execution of the license agreement, the Company entered into a Share Purchase Agreement (the Share Purchase Agreement) with Anchor Life Limited, a company established pursuant to the applicable laws and regulations of Hong Kong and an affiliate of Qilu (the Investor), pursuant to which the Investor purchased 3,579,952 of the Company’s common shares at a purchase price of USD $4.19 per share, which was a 15% premium on the thirty-day average closing price of the Company’s common shares as of the close of trading on December 10, 2021 (the Share Transaction). The Company received $15.0 million of gross proceeds from the Share Transaction on January 6, 2022. The common shares sold to the Investor in the Share Transaction represented approximately 2.5% of the Company’s common shares outstanding immediately prior to the execution of the Share Purchase Agreement.

In June 2025, the Company and Qilu mutually agreed to conclude the strategic partnership and terminated the Qilu License Agreement and related agreements, and the Company now once again holds global rights for imdusiran. As no obligations remain under the Qilu License Agreement, the Company recognized all previously deferred revenue in the second quarter of 2025.

For the period of time the Qilu License Agreement was effective, it fell under the scope of ASC 808 as both parties were active participants in the arrangement and were exposed to significant risks and rewards. While this arrangement was in the scope of ASC 808, the Company analogized to ASC 606 for some aspects of this arrangement, including for the delivery of a good or service (i.e., a unit of account). In accordance with the guidance, the Company identified the following commitments under the arrangement: (i) rights to develop, use, sell, have sold, offer for sale and import any product comprised of Licensed Product (as defined in the Qilu License Agreement) (the Qilu License) and (ii) drug supply obligations and manufacturing technology transfer (the Manufacturing Obligations). The Company determined that these two commitments were not distinct performance obligations for purposes of recognizing revenue as the manufacturing process is highly specialized and Qilu would not be able to benefit from the Qilu License Agreement without the Company’s involvement in the manufacturing activities until the

transfer of the manufacturing know-how was complete. As such, the Company combined these commitments into one performance obligation to which the transaction price was allocated and recognized this transaction price associated with the bundled performance obligation over time using an inputs method based on labor hours expended by the Company on its Manufacturing Obligations.

The Company determined the initial transaction price of the combined performance obligation to be $50.4 million, which includes the $40.0 million upfront fee, $4.4 million of withholding taxes paid by Qilu on behalf of the Company and the premium paid for the Share Transaction of $4.1 million. The Company determined the Milestone Payments to be variable consideration subject to constraint at inception. At the end of each subsequent reporting period, the Company will reevaluate the probability of achievement of the future development, regulatory, and sales milestones subject to constraint and, if necessary, will adjust its estimate of the overall transaction price. Any such adjustments will be recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment.

Due to the conclusion of the strategic partnership with Qilu, the Company recognized the remainder of the $9.6 million of deferred revenue during the twelve months ended December 31, 2025. The Company also recognized $0.8 million of revenue based on labor hours expended by the Company on its Manufacturing Obligations during the twelve months ended December 31, 2025. The Company recognized $1.4 million of revenue during the twelve months ended December 31, 2024, related to labor hours expended.

The Company incurred $0.6 million of incremental costs in obtaining the Qilu License Agreement, which was capitalized in other current assets and other assets and amortized as a component of general and administrative expense commensurate with the recognition of the combined performance obligation. The Company recognized the remainder of the amortization expense at the conclusion of the strategic partnership, recognizing a total of $0.2 million of amortization expense during the twelve months ended December 31, 2025. The Company recognized amortization expense of less than $0.1 million for the twelve months ended December 31, 2024.

Until the conclusion of the strategic partnership with Qilu, the Company reevaluated the transaction price and the total estimated labor hours expected to be incurred to satisfy the performance obligations and adjusted the deferred revenue at the end of each reporting period, which resulted in changes to the amount of collaboration revenue recognized and deferred revenue.

Barinthus Biotherapeutics plc

In July 2021, the Company entered into a clinical collaboration agreement with Barinthus Biotherapeutics plc (Barinthus), formerly Vaccitech plc, pursuant to which the Company completed IM-PROVE II, a Phase 2a proof-of-concept clinical trial evaluating the safety, antiviral activity and immunogenicity of a combination treatment with Barinthus’ VTP-300, an HBV immunotherapeutic, administered after imdusiran in patients with cHBV infection. This clinical trial was amended to include a treatment arm with the addition of an approved PD-1 monoclonal antibody inhibitor, nivolumab (Opdivo).

The Company was responsible for managing this Phase 2a proof-of-concept clinical trial, subject to oversight by a joint development committee comprised of representatives from the Company and Barinthus. The Company and Barinthus retained full rights to their respective product candidates and split all costs associated with the clinical trial. The Company incurred $1.4 million and $2.1 million of costs related to the collaboration, net of Barinthus’s 50% share, during the years ended December 31, 2025 and 2024, respectively, and reflected those costs in research and development in the statements of operations and comprehensive loss.

Royalty Entitlements

Alnylam Pharmaceuticals, Inc. and Acuitas Therapeutics, Inc.

In 2012, the Company entered into the LNP License Agreement with Alnylam that entitles Alnylam to develop and commercialize products with the Company’s LNP technology in exchange for milestone and royalty payments. The Company has two royalty entitlements to Alnylam’s global net sales of ONPATTRO. In addition, the Company is entitled to receive payments upon the achievement of contractual milestones related to Alnylam’s use of the Company’s proprietary LNP technology for other products.

Alnylam launched ONPATTRO, the first approved application of the Company’s LNP technology, in 2018. Under the terms of this license agreement, the Company is entitled to tiered royalty payments on global net sales of ONPATTRO ranging from 1.00% - 2.33% after offsets, with the highest tier applicable to annual net sales above $500 million. This royalty interest was sold to OMERS, effective as of January 1, 2019, for $20 million in gross proceeds before advisory fees. OMERS will retain this entitlement until it has received $30 million in royalties, at which point 100% of this royalty entitlement on future global net sales of ONPATTRO will revert back to the Company. OMERS has assumed the risk of collecting up to $30.0 million of future royalty payments from Alnylam and the Company is not obligated to reimburse OMERS if they fail to collect any such future royalties. If this royalty entitlement reverts to the Company, it has the potential to provide an active royalty stream or to be otherwise monetized again in full or in part. From the inception of the royalty sale through December 31, 2025, an aggregate of $26.5 million of royalties have been earned by OMERS. See Note 9 for further details.

The Company is also receiving a second royalty interest ranging from 0.75% to 1.125% on global net sales of ONPATTRO, with 0.75% applying to sales greater than $500 million, originating from a settlement agreement and subsequent license agreement with Acuitas Therapeutics, Inc. (Acuitas). This royalty entitlement from Acuitas has been retained by the Company and was not part of the royalty entitlement sale to OMERS.

Gritstone Oncology, Inc.

On October 16, 2017, the Company entered into a license agreement with Gritstone that granted them worldwide access to its portfolio of proprietary and clinically validated LNP technology and associated intellectual property to deliver Gritstone’s self-replicating, non-mRNA, RNA-based neoantigen immunotherapy products. Gritstone paid the Company an upfront payment, and will make payments for achievement of development, regulatory, and commercial milestones and royalties. As a result of the Company’s agreement with Genevant (see Note 5 for details), from April 11, 2018 going forward, Genevant is entitled to 50% of the revenues earned by the Company from Gritstone. Gritstone filed for Chapter 11 bankruptcy protection in October 2024, which resulted in Seattle Project Corp. purchasing most of the assets of Gritstone, including the rights under this license agreement. There was no change to the Company’s rights under this license agreement as a result of the bankruptcy and sale of assets.

The Company is the agent in this arrangement and records revenue on a net basis. Milestone payments that are not within the control of the Company or the licensee, such as those that require regulatory approvals, are not considered probable of being achieved until those approvals are received. The Company did not receive any payments from Gritstone or Seattle Project Corp. during the years ended December 31, 2025 or 2024.

Revenues from the Company’s royalty entitlements are summarized in the following table:


	Year ended December 31,
	2025		2024
	(in thousands)
Revenue from collaborations and licenses
Royalties from sales of ONPATTRO	$	1,667	$	2,562
Qilu Pharmaceutical Co., Ltd.	10,434		1,357
Other milestone and royalty payments	500		—
Non-cash royalty revenue
Royalties from sales of ONPATTRO	1,482		2,252
Total revenue	$	14,083	$	6,171

Insider Trading Policies and Procedures	12 Months Ended
Insider Trading Policies and Procedures	Dec. 31, 2025
Insider Trading Policies and Procedures [Line Items]
Insider Trading Policies and Procedures Adopted	true

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Revenue
Revenue	$ 14,083	$ 6,171
Operating expenses
Research and development	25,241	54,037
General and administrative	15,893	22,108
Change in fair value of contingent consideration	(1,830)	2,625
Restructuring costs	12,939	3,720
Total operating expenses	52,243	82,490
Loss from operations	(38,160)	(76,319)
Other income
Interest income	4,068	6,585
Gain on sale of property and equipment	674	0
Interest expense	(97)	(137)
Foreign exchange gain / (loss)	14	(49)
Total other income	4,659	6,399
Net loss	$ (33,501)	$ (69,920)
Loss per share
Basic (in USD per share)	$ (0.17)	$ (0.38)
Diluted (in USD per share)	$ (0.17)	$ (0.38)
Weighted average number of common shares
Basic (in shares)	191,599,600	185,608,874
Diluted (in shares)	191,599,600	185,608,874
Comprehensive loss
Unrealized gain on available-for-sale securities	$ 37	$ 286
Comprehensive loss	(33,464)	(69,634)
Collaborations and licenses
Revenue
Revenue	12,601	3,919
Non-cash royalty revenue
Revenue
Revenue	$ 1,482	$ 2,252

Related party transactions (Details)	Aug. 05, 2025 shares
Director \| Consulting Services
Related Party Transaction [Line Items]
Options granted (in shares)	400,000

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Leases (Tables)

12 Months Ended

Dec. 31, 2025

Leases [Abstract]

Schedule of lease cost

Weighted average remaining lease term and discount rate were as follows:


			As of December 31, 2025
Weighted-average remaining lease term (years)			1.3
Weighted average discount rate			9.0%

The Company did not include options to extend its lease terms as part of its ROU asset and lease liabilities.

Supplemental cash flow information related to the Company’s operating lease was as follows:


	Twelve Months Ended December 31,
	2025		2024
	(in thousands)
Cash paid for amounts included in the measurement of lease liabilities	$	634	$	616

Schedule of lease maturity

Future minimum lease payments under the Company’s operating lease as of December 31, 2025 were as follows:


	As of December 31, 2025
	(in thousands)
2026	$	654
2027	133
2028	—
2029	—
2030	—
Thereafter	—
Total lease payments	$	787
Less: interest	(41)
Present value of lease payments	$	746

Income taxes - Provision/Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Income Tax Disclosure [Abstract]
Domestic	$ 11,952	$ (1,671)
Foreign	(45,453)	(68,249)
Loss before income taxes	$ (33,501)	$ (69,920)

Accounts payable and accrued liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Payables and Accruals [Abstract]
Trade accounts payable	$ 1,173	$ 2,316
Payroll accruals	2,159	3,393
Research and development accruals	412	691
Professional fee accruals	1,075	1,164
Restructuring Reserve	640	0
Accounts payable and accrued liabilities	$ 5,459	$ 7,564

Stock-based compensation - Restricted Stock Units (Details) - $ / shares	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Number
Balance at end of period (in shares)	1,529,959
Arbutus Plans \| Restricted Stock Units (RSUs)
Number
Balance at beginning of period (in shares)	1,493,136
Restricted stock units granted (in shares)	1,968,509
Issuance of common shares pursuant to exercise of options (in shares)	(580,584)
Restricted stock units forfeited, canceled or expired (in shares)	(1,351,102)
Balance at end of period (in shares)	1,529,959	1,493,136
Weighted-Average Grant-Date Fair Value
Balance at beginning of period (in dollars per share)	$ 2.57
Weighted average grant date fair value (in dollars per share)	3.58	$ 2.40
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price	2.61
Restricted stock units forfeited, canceled or expired (in dollars per share)		2.90
Balance at end of period (in dollars per share)	$ 3.55	$ 2.57

Segment Reporting

12 Months Ended

Dec. 31, 2025

Segment Reporting [Abstract]

Segment Reporting Disclosure

Segment Reporting

The Company has one reportable segment. The Company’s chief operating decision maker is the Chief Executive Officer and President. The accounting policies of the single segment are the same as those described in the summary of significant accounting policies. The chief operating decision maker assesses performance for the single segment and decides how to allocate resources based on net loss that also is reported on the statement of operations and comprehensive loss as consolidated net loss. The chief operating decision maker uses net loss to monitor budget versus actual results and to evaluate the overall cash burn of the business.


	Year ended December 31,
	2025		2024
	(in thousands)
Revenue	$	14,083	$	6,171
Less:
Research and development employee expense, lab supplies and overhead	13,961		26,613
Imdusiran IM-PROVE I, II & III clinical trials expense	4,824		15,735
AB-101-001 Phase 1a/1b clinical trial expense	6,220		10,196
Other early research and development programs expense	236		1,493
General and administrative expense	15,893		22,108
Restructuring expense	12,939		3,720
Other segment expense (1)	(1,747)		2,811
Add:
Interest income	4,068		6,585
Gain on sale of property and equipment	674		—
Segment net loss	$	(33,501)	$	(69,920)
Adjustments and reconciling items	—		—
Consolidated net loss	$	(33,501)	$	(69,920)

(1) Other segment expense includes the change in the fair value of contingent consideration, non-cash interest expenses and foreign currency exchange gains and losses.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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+ Details