Korro Bio, Inc.

1. The Company and Liquidity

Nature of Business

Korro Bio, Inc. (together with its subsidiaries, the “Company”) is a biopharmaceutical company with a mission to discover, develop and commercialize a new class of genetic medicines based on editing RNA, enabling the treatment of both rare and highly prevalent diseases. The Company was incorporated in November 2014 as a Delaware corporation and in November 2023 completed a reverse merger through a now wholly-owned subsidiary and changed its name from Frequency Therapeutics, Inc. (“Frequency”) to Korro Bio, Inc. The Company's principal offices are in Cambridge, Massachusetts.

Risks and Uncertainties

The Company is subject to risks common to companies in the biotechnology industry including, but not limited to, new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations and the need to obtain additional financing. Lead candidates and development candidates currently under development will require significant additional research and development efforts, including extensive pre-clinical and clinical testing and regulatory approval, prior to commercialization. These efforts will require significant amounts of additional capital, adequate personnel infrastructure and extensive compliance-reporting capabilities. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize revenue from product sales.

Liquidity and Capital Resources

The Company’s consolidated financial statements have been prepared on the basis of the Company continuing as a going concern. The Company expects that its existing cash, cash equivalents and marketable securities will enable the Company to fund its planned operating expense and capital expenditure requirements for at least 12 months from the date of issuance of these consolidated financial statements. The Company has incurred recurring losses and negative cash flows from operations since inception. As of December 31, 2025, the Company had an accumulated deficit of $383.8 million. The Company expects its operating losses and negative operating cash flows to continue into the foreseeable future. The future viability of the Company is dependent on its ability to generate cash from operating activities or to raise additional capital to finance its operations. There can be no assurance that the Company will ever earn product revenues or achieve profitability, or if achieved, that the revenues or profitability will be sustained on a continuing basis. In addition, the Company’s preclinical and clinical development activities, manufacturing and commercialization of the Company’s development candidates, if approved, will require significant additional financing. However, if the Company is unable to obtain additional financing, the Company would be forced to delay, reduce or eliminate its research and development programs and/or relinquish valuable rights to its technology, lead candidates anddevelopment candidates. There is no assurance that the Company will be successful in obtaining sufficient financing on acceptable terms to continue funding its operations.

2. Basis of Presentation and Summary of Significant Accounting Policies

Basis of Presentation and Consolidation

The accompanying consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”). These consolidated financial statements have been prepared on the going concern basis of accounting, which assumes continuity of operations, realization of assets and satisfaction of liabilities in the ordinary course of business.

The consolidated financial statements include the accounts of Korro Bio, Inc. and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.

Use of Estimates

The preparation of the Company’s consolidated financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, impairment of long-lived assets and stock-based compensation expense. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it has concluded to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates as there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results may differ materially from those estimates or assumptions.

Foreign Currency Translation and Transactions

The majority of the Company’s operations occur in entities that have the U.S. dollar as their functional currency. Non-U.S. dollar denominated functional currency subsidiary has assets and liabilities translated into U.S. dollars at rates of exchange in effect at the end of the year. Revenue and expense amounts are translated using the average exchange rates for the period. Net unrealized gains and losses resulting from foreign currency translation are included in “Accumulated other comprehensive income" on the Company's consolidated balance sheets. Net foreign currency exchange transaction gains or losses are included in “Other income, net” on the Company’s consolidated statement of operations, the impact of which is not significant.

Cash Equivalents

Cash equivalents are highly-liquid investments that are readily convertible into cash with original maturities of three months or less when purchased. These assets include investments in money market funds that invest in U.S. Treasury obligations. Cash equivalents are reflected at fair value based on quoted market prices, as further described in Note 3, “Fair Value Measurements”.

Fair Value Measurements

ASC Topic 820, Fair Value Measurement, (“ASC 820”) establishes a fair value hierarchy for an asset or liability measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs). Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances.

ASC 820 identifies fair value as the exchange price, or exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a three-tier fair value hierarchy that distinguishes between the following:

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Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities.

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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.

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Level 3 inputs are unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability.

The hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. The classification of fair value measurements within the hierarchy is based upon the lowest level of input that is significant to the measurement. See Note 3 for further discussion of fair value measurements.

Investments

Investments consist of securities with original maturities greater than three months when purchased. Short-term investments consist of investments that are available for use in current operations. Long-term investments consist of investments with maturities of greater than one year that are not available for use in current operations.

The Company classifies all of its investments as available-for-sale securities. Accordingly, these investments are recorded at fair value. Realized gains and losses and amortization and accretion of discounts and premiums are included in “Other income, net”. Unrealized gains and losses on available-for-sale securities are included in “Accumulated other comprehensive loss” as a component of stockholders’ deficit until realized.

The Company reviews its investment portfolio to identify and evaluate investments that have indicators of possible other-than-temporary impairment. Factors considered in determining whether a loss is other-than-temporary include the length of time and extent to which fair value has been less than the cost basis, the financial condition of the issuer and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value. Credit losses are identified when the Company does not expect to receive cash flows sufficient to recover the amortized cost basis of a security. In the event of a credit loss, only the amount associated with the credit loss is recognized in operating results, with the amount of loss relating to other factors recorded in accumulated other comprehensive income.

Accounts Receivable

The Company's accounts receivable is comprised of amounts due related to its collaboration agreement with Novo Nordisk (see Note 12). The Company monitors the financial performance and credit worthiness of its counterparties so that it can properly assess and respond to changes in their credit profile. The Company provides allowances against receivables for estimated losses, if any, that may result from a counterparty's inability to pay. Amounts determined to be uncollectible are written-off against the allowance.

Property and Equipment

Property and equipment are recorded at cost and consists of laboratory equipment, furniture and office equipment, computer equipment, leasehold improvements, and construction in progress. The Company capitalizes property and equipment that is acquired for research and development activities and that has alternative future use. Expenditures for repairs and maintenance are recorded to expense as incurred, whereas major betterments are capitalized as additions to property and equipment. Property and equipment not yet placed into service is capitalized as construction in progress and is depreciated once placed into service. Leasehold improvements are depreciated over the lesser of their useful lives or the term of the lease. Depreciation, including depreciation for assets recorded under finance leases, is calculated over the estimated useful lives of the assets using the straight-line method.

Long-Lived Assets

The Company periodically evaluates long-lived assets for impairment when changes in circumstances or the occurrence of certain events indicate the carrying amount of an asset or asset group may not be recoverable. If any impairment indicators are present, or if other circumstances indicate that an impairment might exist, the Company performs a recoverability test, to determine whether an impairment loss should be measured. The Company groups long-lived assets and liabilities at the lowest level for which there are identifiable cash flows that are largely independent of the cash flows of the other assets and liabilities and estimates the future net undiscounted cash flows expected to be generated from the use of the long-lived asset (group) and its eventual disposal. If the undiscounted cash flows used in the recoverability test are less than the carrying amount of the long-lived asset (group), the Company is required to determine the fair value of the long-lived asset (group) and recognize an impairment loss if the carrying amount of the long-lived asset (group) exceeds its fair value. Fair value is estimated as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.

Identifying and assessing whether impairment indicators exist, or if events or changes in circumstances have occurred, including an adverse change in legal factors or in the business climate that could affect the value of the long-lived asset (group); an adverse change in the extent or manner in which the long-lived asset (group) is used or is expected to be used, or in its physical condition; and current or forecasted operating or cash flow losses that demonstrate continuing losses associated with the use of the long-lived asset (group), requires judgment. Additionally, grouping assets requires judgment.

In November 2025, the Company announced that its first-generation alpha-1 antitrypsin deficiency (“AATD”) program, KRRO-110, its proprietary RNA editing oligonucleotide with a liquid nano particle delivery system, did not reach projected levels of functional protein following a single administration. The Company pivoted to GalNAc delivery for AATD and terminated its REWRITE clinical program investigating KRRO-110 as a treatment for AATD. In connection with the November 2025 announcement regarding KRRO-110, the Company further implemented a strategic restructuring to reserve resources and extend cash runway, including a reduction in its workforce. Additionally, in November 2025, the Company announced that the Company and Novo Nordisk A/S (“Novo Nordisk”) entered into an amendment to the research collaboration and license agreement under which the Company and Novo Nordisk agreed to pause the research collaboration and license agreement for 12 months. Following these announcements, the Company determined that indicators of impairment existed during the fourth quarter of 2025 and, as a result, the Company's long-lived assets were reviewed for impairment. The Company assessed the recoverability of its single enterprise-wide asset group and determined that the assets were not fully recoverable when compared to the future undiscounted cash flows from the asset group. As a result, the Company estimated the fair value of the asset group, which resulted in a non-cash, long-lived asset impairment charge of $30.9 million in 2025. The $30.9 million consists of $15.0 million and $15.9 million of impairment charges on the Company's operating right-of-use (“ROU”) asset and property and equipment, respectively. See Note 3 for further discussion of the impairment analysis.

Leases

Under ASC Topic 842, Leases (“ASC 842”), the Company determines whether an arrangement is or contains a lease at inception. For leases with a term of 12 months or less, the Company doesnot recognize a right-of-use asset or lease liability. The Company’s operating leases are recognized on its consolidated balance sheets as noncurrent assets, current liabilities and noncurrent liabilities. The Company does not have any finance leases.

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 liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. As the Company’s leases typically do not provide an implicit rate, the Company uses an estimate of its incremental borrowing rate based on the information available at the lease commencement date in determining the present value of lease payments. Lease expense is recognized on a straight-line basis over the lease term. The Company typically only includes an initial lease term in its assessment of a lease arrangement. Options to renew or options to terminate a lease are not included in the Company’s assessment unless there is reasonable certainty that the Company will exercise such options, respectively.

The Company has elected to account for the lease and non-lease components together for existing classes of underlying assets.

Preferred Stock

The Company applies the guidance of ASC Topic 480, Distinguishing Liabilities from Equity (“ASC 480”), when determining the classification and measurement of its preferred stock. Preferred stock subject to mandatory redemption (if any) are classified as liability instruments and are measured at fair value. The Company classifies contingently redeemable preferred stock (if any), which includes preferred stock that features redemption rights that are either within the control of the holder or subject to redemption upon the occurrence of uncertain events not solely within the Company’s control, as temporary equity. At all other times, the Company classifies its preferred stock in stockholders’ equity.

Revenue Recognition and Deferred Revenue

The Company accounts for contracts with customers in accordance with ASC Topic 606, Revenue from Contracts with Customers (ASC 606). The Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (i) identify the 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) the Company satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the Company will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied.

Performance obligations promised in a contract are identified based on the goods and services that will be transferred to the customer that are both capable of being distinct and are distinct in the context of the contract. To the extent a contract includes multiple promised goods and services, the Company applies judgment to determine whether promised goods and services are both capable of being distinct and are distinct in the context of the contract. If these criteria are not met, the promised goods and services are accounted for as a combined performance obligation.

The transaction price is determined based on the consideration to which the Company will be entitled in exchange for transferring goods and services to the customer. To the extent the transaction price includes variable consideration, the Company estimates the amount of variable consideration that should be included in the transaction price utilizing either the expected value method or the most likely amount method, depending on the nature of the variable consideration. Variable consideration is included in the transaction price if, in management’s judgment, it is probable that a significant future reversal of cumulative revenue under the contract will not occur. Any estimates, including the effect of the constraint on variable consideration, are evaluated at each reporting period for any changes.

If the contract contains a single performance obligation, the entire transaction price is allocated to the single performance obligation. Contracts that contain multiple performance obligations require an allocation of the transaction price to each performance obligation on a relative standalone selling price basis unless the transaction price is variable and meets the criteria to be allocated entirely to a performance obligation or to a distinct service that forms part of a single performance obligation.

The Company satisfies performance obligations either over time or at a point in time. Revenue is recognized over time if either (i) the customer simultaneously receives and consumes the benefits provided by the entity’s performance, (ii) the entity’s performance creates or enhances an asset that the customer controls as the asset is created or enhanced, or (iii) the entity’s performance does not create an asset with an alternative use to the entity and the entity has an enforceable right to payment for performance completed to date. If the entity does not satisfy a performance obligation over time, the related performance obligation is satisfied at a point in time by transferring the control of a promised good or service to a customer.

Licenses of intellectual property, or IP: If the license to the Company’s IP is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from consideration allocated to the license when the license is transferred to the customer and the customer can use and benefit from the licenses. For licenses that are combined with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. The Company generally recognizes revenue using the cost incurred to date as compared to the total estimated cost. The impact on revenue of changes in total estimated costs are recognized on a cumulative basis in the period that the change occurs. If estimates of the total cost change, or if contract amendments change the scope of the performance obligation, the required adjustments to revenue could be material.

Milestone payments: At the inception of each arrangement that includes development or regulatory milestone payments, the Company evaluates the probability of reaching the milestones and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur in the future, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control or the licensee’s, such as regulatory approvals, are not considered probable of being achieved until those approvals are received and therefore consideration included in the transaction price is constrained. The transaction price is then allocated to each performance obligation on a relative standalone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such development milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment.

Commercial milestone payments and royalties: For arrangements that include sales-based royalties, including milestone payments based on levels of sales, if the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied).

When no remaining performance obligations are required of the Company, or following the completion of the performance obligation period, such amounts are recognized as revenue upon transfer of control of the goods or services to the customer.

Consideration received prior to revenue recognition is recorded as deferred revenue in the consolidated balance sheets. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as current portion of deferred revenue in the accompanying consolidated balance sheets. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion. Amounts are recorded as accounts receivable if the Company transfers goods or services to a customer before the customer pays consideration and the Company’s right to consideration is unconditional. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is that the period between payment by the customer and the transfer of the promised goods or services to the customer will be one year or less.

Expenditures relating to research and development are expensed as incurred. Research and development expenses include external expenses incurred under arrangements with third parties, such as contract research organizations, academic and non-profit institutions and consultants; salaries and personnel-related costs, including non-cash stock-based compensation expense; license fees to acquire in-process technology and other expenses, which include direct and allocated expenses for laboratory, facilities and other costs. Non-refundable advance payments for goods and services that will be used in future research and development activities are expensed when the activity has been performed or when the goods have been received rather than when the payment is made.

As part of the process of preparing the consolidated financial statements, the Company is required to estimate its accrued research and development expenses as of each balance sheet date. In accruing service fees, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. This process involves reviewing open contracts and purchase orders, communicating with internal personnel and vendors to identify services that have been performed on the Company’s behalf and estimating the level of service performed and the associated cost incurred for the service when the Company has not yet been invoiced or otherwise notified of the actual cost. The Company periodically confirms the accuracy of its estimates with its service providers and makes adjustments if necessary. The majority of the Company’s service providers invoice monthly in arrears for services performed or when contractual milestones are met. The financial terms of agreements with these service providers are subject to negotiation, vary from contract-to-contract and may result in uneven payment flows. In circumstances where amounts have been paid in excess of costs incurred, the Company records a prepaid expense.

Intellectual Property Expenses

The Company expenses legal costs related to patent applications as they are incurred. Such costs are classified as general and administrative expenses within the consolidated statements of operations and comprehensive loss.

Stock-based Compensation

The Company accounts for stock-based payments in accordance with ASC Topic 718, Compensation—Stock Compensation(“ASC 718”). This guidance requires all stock-based payments, including grants of stock options and restricted common stock, to be recognized as expense in the consolidated statements of operations and comprehensive loss based on their grant date fair values. For stock options granted to employees, non-employees and members of the Company’s Board of Directors for their services on the Board of Directors, the Company estimates the grant date fair value of each stock option using the Black-Scholes option-pricing model. For restricted common stock granted to employees and non-employees, the Company estimates the grant date fair value of each award using the intrinsic value, which is based on the value of the underlying common stock less any purchase price. For stock-based payments subject to service-based vesting conditions, the Company recognizes stock-based compensation expense equal to the grant date fair value of stock-based payment on a straight-line basis over the requisite service period.

In addition to the grant date fair value of the Company’s common stock, the Black-Scholes option pricing model requires the input of certain subjective assumptions, including (i) the calculation of expected term of the stock-based payment, (ii) the risk-free interest rate, (iii) the expected stock price volatility and (iv) the expected dividend yield. The Company uses the simplified method as proscribed by SEC Staff Accounting Bulletin No. 107 to calculate the expected term for stock options granted to employees as the Company does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. The Company determines the risk-free interest rate based on a treasury instrument whose term is consistent with the expected term of the stock options. Due to the lack of Company-specific historical and implied volatility data, the Company bases its estimates of expected volatility on the historical volatility of a group of publicly-traded companies with similar characteristics to itself, including stage of product development and therapeutic focus within the life sciences industry. The expected volatility has been determined using a weighted-average of the historical volatility measures of this group of companies. The Company expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded stock price. Historical volatility is calculated over a period of time commensurate with the expected term of the stock-based payment. The Company uses an assumed dividend yield of zero as the Company has never paid dividends on its common stock, nor does it expect to pay dividends on its common stock in the foreseeable future.

The Company accounts for forfeitures of all stock-based payments when such forfeitures occur.

Income Taxes

Income taxes are recorded in accordance with ASC Topic 740, Income Taxes, which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. A valuation allowance against deferred tax assets is recorded if, based on the weight of the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized.

The Company accounts for uncertain tax positions using a more-likely-than-not threshold for recognizing and resolving uncertain tax positions. The evaluation of uncertain tax positions is based on factors, including, but not limited to, changes in the law, the measurement of tax positions taken or expected to be taken in tax returns, the effective settlement of matters subject to audit, new audit activity and changes in facts or circumstances related to a tax position.

Interest and penalty charges, if any, related to income taxes would be classified as a component of the “Provision for income taxes” in the consolidated statements of operations and comprehensive loss.

Net Loss per Share

Net loss per share attributable to common stockholders is calculated using the two-class method, which is an earnings allocation formula that determines net loss per share for the holders of the Company’s common shares and participating securities. The Company’s Preferred Stock contains participation rights in any dividend paid by the Company and is deemed to be a participating security. Net income attributable to common stockholders and participating preferred shares are allocated to each share as if all of the earnings for the period had been distributed. The participating securities do not include a contractual obligation to share in losses of the Company and are not included in the calculation of net loss per share in the periods in which a net loss is recorded. Net loss attributable to common stockholders is equal to the net loss for the period.

Diluted net loss per share is computed using the more dilutive of (a) the two-class method or (b) the treasury stock method and if-converted method. The Company allocates earnings first to preferred stockholders based on dividend rights and then to common and preferred stockholders based on ownership interests. The weighted-average number of common shares included in the computation of diluted net loss gives effect to all potentially dilutive common equivalent shares, including outstanding stock options and Preferred Stock. Common stock equivalent shares are excluded from the computation of diluted net loss per share if their effect is antidilutive. In periods in which the Company reports a net loss attributable to common stockholders, diluted net loss per share attributable to common stockholders is generally the same as basic net loss per share attributable to common stockholders since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive.

Concentration of Credit Risk and Off-Balance Sheet Risk

Financial instruments that potentially expose the Company to concentrations of credit risk primarily consist of cash, cash equivalents and investments. Cash balances are deposited with federally-insured financial institutions in the United States and may, at times, exceed federally-insured limits. The Company maintains its cash, cash equivalents and investments with high-quality financial institutions and, consequently, the Company believes that such funds are subject to minimal credit risk. The Company’s cash equivalents are comprised of money market funds that are invested in U.S. Treasury and government agency obligations. The Company’s investments are comprised of government securities. Credit risk in these securities is reduced as a result of the Company’s investment policy to limit the amount invested in any single issuer and to only invest in securities of a high credit quality.

The Company relies, and expects to continue to rely, on a small number of vendors to manufacture supplies and to process its lead candidates and development candidates for its development programs. These programs could be adversely affected by a significant interruption in the manufacturing process or supply chain.

The Company has no significant off-balance sheet risk such as foreign exchange contracts, option contracts or other foreign hedging arrangements.

New and Recently Adopted Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board, or FASB, or other standard setting bodies that the Company adopts as of the specified effective date. Unless otherwise discussed below, the Company does not believe that the adoption of recently issued standards have or may have a material impact on its consolidated financial statements and disclosures.

In December 2023, the FASB issued ASU 2023-09, Improvements to Income Tax Disclosures, which requires entities to disclose disaggregated information about their effective tax rate reconciliation and income taxes paid. The disclosure requirements will be applied on a prospective basis, with the option to apply them retrospectively. The Company adopted ASU 2023-09 retrospectively for the year ended December 31, 2025, and it did not have a material impact on the Company's consolidated financial statements.

In November 2024, the FASB issued ASU 2024-03, Income Statement-Reporting Comprehensive Income- Expense Disaggregation Disclosures, which requires disclosure of additional information about specific expense categories in the notes to the financial statements on an interim and annual basis. The standard is effective for fiscal years beginning after December 15, 2026, and for interim periods beginning after December 15, 2027, with early adoption permitted. The Company is currently evaluating the disclosure requirements related to this new standard.

3. Fair Value Measurements

Recurring Fair Value Measurements

The Company measures the fair value of money market funds based on quoted prices in active markets for identical securities. Marketable securities include U.S. treasury bills and U.S. government agency securities that are valued either based on recent trades of securities in inactive markets or based on quoted market prices of similar instruments and other significant inputs derived from or corroborated by observable market data.

The carrying amounts reflected in the consolidated balance sheets for cash, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values, due to their short-term nature.

Assets and liabilities measured at fair value on a recurring basis as of December 31, 2025 were as follows (in thousands):

Assets and liabilities measured at fair value on a recurring basis as of December 31, 2024 were as follows (in thousands):

The fair value of the CVR liability and the MS APA are based on significant unobservable inputs, which represent Level 3 measurements within the fair value hierarchy. In determining the fair value of the CVR liability and the MS APA asset, the Company used the income approach, primarily discounted cash flow models. The discounted cash flow models require the use of significant judgment, estimates and assumptions, including the probability of technical and regulatory success, and discount rates. For the year ended December 31, 2025, the aggregate change in fair value of the CVR liability and MS APA asset was$0.1 million. For the year ended December 31, 2024, the aggregate change in fair value of the CVR liability and MS APA asset was $0.1 million.

There were no changes in valuation techniques, nor were there any transfers among the fair value hierarchy levels during the years ended December 31, 2025 or 2024.

Nonrecurring Fair Value Measurements

The Company determined that indicators of impairment existed during the fourth quarter of 2025 and, as a result, the Company's long-lived assets were reviewed for impairment. The Company assessed the recoverability of its single enterprise-wide asset group and determined that the assets were not fully recoverable when compared to the future undiscounted cash flows from the asset group. As a result, the Company estimated the fair value of the asset group which resulted in a non-cash, long-lived asset impairment charge of $30.9 million in 2025. The asset impairment charge was recorded as Long-lived asset impairment charge in the consolidated statement of operations and comprehensive loss for the year ended December 31, 2025. The $30.9 million consists of$15.0 million and $15.9 million of impairment charges on the Company's operating ROU asset and property and equipment, respectively. The impairment charge was allocated to the long-lived assets of the asset group on a pro rata basis using the relative carrying amount of those assets. The fair value of the single enterprise-wide asset group was calculated using the Company’s market capitalization at the date the impairment indicators were identified using Level 1 inputs.

4. Marketable Securities

Marketable Securities as of December 31, 2025 were comprised as follows (in thousands):

Marketable securities were comprised as follows as of December 31, 2024 (in thousands):

The amortized cost of available-for-sale securities is adjusted for amortization of premiums and accretion of discounts to maturity. There wereno realized gains or losses on available-for-sale securities for the periods presented. None of the investments were in an unrealized loss position for greater than 12 months as of December 31, 2025. The unrealized losses on the Company's available-for-sale securities were caused by the impact of central bank and market interest rates on the investments held. The Company does not intend to sell the investments, and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost bases. After analyzing the securities in an unrealized loss position, the portion of these losses that relates to changes in credit quality is insignificant. The Company didnot record an allowance for credit losses as of December 31, 2025. Furthermore, the Company does not believe that these securities expose the Company to undue market risk or counterparty credit risk.

5. Restricted Cash

As of December 31, 2025, the Company maintained current restricted cash of $1.0 million and non-current restricted cash of $2.4 million. The current restricted cash of $1.0 million is included under the caption “prepaid expenses and other current assets” in the Company's consolidated balance sheet. As of December 31, 2024, the Company maintainedno current restricted cash and non-current restricted cash of $3.4 million. All restricted cash amounts are comprised solely of letters of credit required pursuant to the Company's facility lease.

The following table provides a reconciliation of cash, cash equivalents and restricted cash as of December 31, 2025 and 2024 that sums to the total of the same amounts shown in the consolidated statements of cash flows (in thousands):

6. Property and Equipment, Net

Property and equipment, net, as of December 31, 2025 and 2024 was comprised as follows (in thousands):

Depreciation expense for the years ended December 31, 2025 and 2024 was $4.3 million and $3.6 million, respectively.

During the fourth quarter of 2025, the Company recorded a non-cash, long-lived asset impairment charge of $15.9 million related to property and equipment. See Note 3 for further discussion of the impairment charge.

7. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities as of December 31, 2025 and 2024 were comprised as follows (in thousands):

8. Common Stock

As of December 31, 2025, the Company was authorized to issue 200,000,000 shares of common stock, $0.001 per value per share. Holders of common stock are entitled to one vote per share. In addition, holders of common stock are entitled to receive dividends, if and when declared by the Company’s Board of Directors. As of December 31, 2025, no dividends had been declared.

As of December 31, 2025 and 2024, the Company had reserved for future issuance the following number of shares of common stock:

PIPE Offering

On April 17, 2024, the Company entered into a subscription agreement with certain new and existing accredited investors to issue and sell an aggregate of 1,249,283 shares of its common stock in a private placement ("PIPE") that resulted in gross proceeds of approximately $70.0 million, before deducting placement agent fees and offering expenses of approximately $2.6 million. The PIPE closed on April 22, 2024.

At-The-Market Equity Program

In December 2024, the Company filed a Shelf Registration Statement on Form S-3 (the "Shelf Registration Statement") with the Securities and Exchange Commission ("SEC"), which covered the offering, issuance and sale by the Company of up to an aggregate of $400.0 million of the Company's common stock, preferred stock, debt securities, units and/or warrants. The Shelf Registration Statement included a prospectus covering the offering, issuance and sale of up to $100.0 million of the Company's common stock from time to time through an "at-the-market" offering under the Securities Act of 1933, as amended.

Subsequently in December 2024, the Company entered into an Open Market Sale Agreement (the “Sales Agreement”) with TD Cowen Securities (USA) LLC or TD Cowen, acting as the Company's Agent and/or principal (the "Sales Agent") with respect to an "at the market offering" program under which the Company may from time to time, at its sole discretion, issue and sell shares of its common stock having an aggregate offering price of up to $100.0 million through the Sales Agent. TD Cowen is entitled to compensation for its services equal to up to 3.0% of the aggregate gross proceed of any shares of common stock sold through TD Cowen under the Sales Agreement. Pursuant to the Sales Agreement, any shares will be sold pursuant to the Shelf Registration Statement filed with the SEC on December 2, 2024, including the base prospectus contained therein, as declared effective by the SEC on December 9, 2024. As of December 31, 2025, there have been no sales of common stock pursuant to the Sales Agreement.

9. Preferred Stock

As of December 31, 2025 and 2024, the Company was authorized to issue up to 10,000,000 shares of preferred stock, at a par value of $0.001 withno preferred stock shares issued or outstanding.

10. Stock-based Compensation

2023 Stock Option and Incentive Plan

In November 2023, the Company’s board of directors adopted the Company’s 2023 Stock Option and Incentive Plan (the “2023 Plan”). The 2023 Plan was approved by the Company’s stockholders in November 2023 and became effective in November 2023 in connection with completion of the Merger. The 2023 Plan initially reserved 885,028 shares for the issuance of stock awards. In addition, the number of shares of common stock available for issuance under the 2023 Plan will be automatically increased on the first day of each calendar year during the ten-year term of the 2023 Plan, beginning with January 1, 2024 and ending with January 1, 2033, by the amount equal to 5% of the outstanding number of shares of the Company’s common stock on December 31 of the preceding calendar year or such lesser amount as determined by the Company’s board of directors. Awards granted under the 2023 Plan expire no later than ten years from the date of grant. For stock options, the option price shall generally not be less than 100% of the fair market value on the day of grant. As of December 31, 2025, there were in aggregate 1,847,780 shares of common stock reserved for issuance and 142,985 shares available to grant under the 2023 Plan. As of December 31, 2024, there were in aggregate 1,368,452 shares of common stock reserved for issuance and 619,923 shares available to grant under the 2023 Plan.

2019 Stock Incentive Plan

In January 2019, the Legacy Korro's Board of Directors adopted the 2019 Stock Incentive Plan (as amended from time to time, the “Legacy Korro Plan”). The Legacy Korro Plan provides for the grant of stock options, stock awards and restricted stock units to employees, members of the Company’s Board of Directors and non-employee consultants and advisors. The Legacy Korro Plan initially provided for the issuance of up to 110,285 shares of common stock. The Legacy Korro Plan was subsequently amended in May 2019, June 2020, October 2020, April 2021, November 2021 and March 2023 to modify the number of shares of common stock issuable under the Legacy Korro Plan. Subsequent to the March 2023 amendment to the Legacy Korro Plan, Legacy Korro could issue up to 747,752 shares of common stock under the Legacy Korro Plan.

In connection with the Merger, each option to purchase shares of Legacy Korro common stock that was outstanding and unexercised under the Legacy Korro Plan immediately prior to the Effective Time, whether or not vested, was converted into an option to purchase shares of the Company’s common stock and became eligible to be registered on Form S-8. The Company assumed each outstanding option to purchase shares of Legacy Korro common stock in accordance with the terms (as in effect as of the date of the Merger Agreement) of the Legacy Korro Plan and the terms of the stock option agreement by which such option to purchase shares of Legacy Korro common stock is evidenced. The number of shares under the Legacy Korro Plan subject to outstanding awards as of the effective date of the 2023 Plan that are subsequently canceled, forfeited or repurchased by the Company will be added to the shares reserved under the 2023 Plan.

The number of shares of common stock reserved for issuance pursuant to outstanding awards under the Legacy Korro Plan as of December 31, 2025 and 2024 was 449,258 shares and 499,759 shares, respectively. There wereno shares available for grant under the Legacy Korro Plan at December 31, 2025 and 2024, respectively. Upon completion of the Merger and effectiveness of the 2023 Plan, the Company ceased granting awards under the Legacy Korro Plan.

Stock-based Compensation Expense

Total stock-based compensation expense recognized in the consolidated statements of operations and comprehensive loss for the years ended December 31, 2025 and 2025 was as follows (in thousands):

Stock Option Activity

The fair value of stock options granted during the years ended December 31, 2025 and 2024 was calculated on the date of grant using the following weighted-average assumptions:

Using the Black-Scholes option pricing model, the weighted-average grant date fair value of stock options granted during the years ended December 31, 2025 and 2024 was$19.33 and $31.80 per share, respectively.

The following table summarizes changes in stock option activity during the year ended December 31, 2025 (in thousands, except per share amounts):

The aggregate intrinsic value of options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the common stock as of the end of the period. The aggregate intrinsic value of stock options exercised during the years ended December 31, 2025 and 2024 was$1.0 million and $5.0 million, respectively.

As of December 31, 2025, there was unrecognized stock-based compensation expense related to unvested stock options of$13.4 million, which the Company expects to recognize over a weighted-average period of approximately 2.7 years.

Restricted Stock Unit Awards

The following table summarizes changes in restricted stock unit award activity during the year ended December 31, 2025 (in thousands, except per share amounts):

The grant date fair value of restricted stock units granted during the year ended December 31, 2025 was $4.0 million.

As of December 31, 2025, there was unrecognized stock-based compensation expense related to unvested restricted stock unit awards of$3.8 million, which the Company expects to recognize over a weighted-average period of approximately 1.0 year.

Compensation cost of $0.2 million and $0.0 million related to the restricted stock units was recognized during the years ended December 31, 2025 and 2024, respectively.

11. Income Taxes

For the years ended December 31, 2025 and 2024, the loss before income taxes consisted of the following (in thousands):

The provision for income taxes for the years ended December 31, 2025 and 2024 was comprised as follows (in thousands):

A reconciliation of the federal statutory income tax rate to the Company’s effective tax rate is as follows (in thousands):

For the years ended December 31, 2025 and 2024, the amount of cash income taxes paid by the Company was as follows (in thousands):

The principal components of the Company’s deferred tax assets and liabilities as of December 31, 2025 and 2024 were comprised as follows (in thousands):

As of December 31, 2025, the Company had federal and state net operating loss (“NOL”) carryforwards $462.0 million and $436.9 million, respectively. Under current law, the Company's federal NOLs generated in taxable years ending after December 31, 2017, may be carried forward indefinitely, but the deductibility of such federal NOLs is limited to 80% of the Company's taxable income annually for tax years beginning after December 31, 2018. Federal NOLs generated in taxable years ending on or prior to December 31, 2017, however, have a 20-year carryforward period, but are not subject to the 80% limitation. The Company has federal NOLs of $22.4 million that are subject to expiration between 2036 and 2037 and has $439.6 million of federal NOLs that do not expire.

State NOLs expire at various dates from 2035 through 2045. As of December 31, 2025, the Company had federal research and development tax credit carryforwards of $20.2 million that expire at various dates from 2037 through 2045. In addition, as of December 31, 2025, the Company had state research and development tax credit carryforwards of $9.9 million that expire at various dates from 2032 through 2040.

The Company has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets, which primarily pertain to NOL carryforwards, tax credit carryforwards and capitalized research and development. The Company has determined that it is more likely than not that it will not realize the benefits of its deferred tax assets, and as a result, a valuation allowance of $202.3 million has been established at December 31, 2025. The increase in the valuation allowance of $34.0 million during the year ended December 31, 2025 was primarily due to the additional operating loss generated by the Company.

NOL and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50% as defined under Sections 382 and 383 in the IRC. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the Company’s value immediately prior to the ownership change. As a result of ownership changes in the Company from its inception through December 31, 2025, the Company’s NOL and tax credit carryforwards allocable to the periods preceding each such ownership change could be subject to limitations under IRC Section 382, however the Company has not yet completed an IRC Section 382 study. The Company’s foreign net operating loss carryforwards may also be limited under similar laws in the foreign jurisdiction.

The Company hadno unrecognized tax benefits as of either December 31, 2025 or 2024. The Company has not conducted a study of its research and development credit carryforwards generated during any year. This study, once completed, may result in an adjustment to the Company’s research and development credit carryforwards.

However, until a study is completed and any adjustment is known, no amounts are being presented as an uncertain tax position. A full valuation allowance has been provided against the Company’s research and development credit carryforwards, and if an adjustment is required, this adjustment would be offset by an adjustment to the valuation allowance. Thus, there would be no impact to the consolidated statements of operations and comprehensive loss if an adjustment were required.

The Company files income tax returns in the United States federal tax jurisdiction and the California, Connecticut, Florida, Massachusetts, New Hampshire, New Jersey and South Carolina state tax jurisdictions. The Company also files an income tax return in Australia for the Company’s Australian subsidiary. Because the Company is in a loss carryforward position, it is generally subject to examination by federal and state tax authorities for all tax years in which a loss carryforward is available.

As of December 31, 2025, the Company hasnot incurred any material interest or penalty charges.

12. Collaboration Agreements

Genevant Agreement

In March 2023, Legacy Korro entered into a collaboration and license agreement (the “Genevant Agreement”) with Genevant Sciences GmbH (“Genevant”). Key financial terms under the Genevant Agreement are as follows:

•

The Company made a $2.5 million payment to Genevant in March 2023 upon execution of the Genevant Agreement and recorded the payment within research and development expense in the consolidated statement of operations for the year ended December 31, 2023.

•

The Company will reimburse Genevant for certain out-of-pocket and full-time equivalent costs incurred as a result of research and development activities performed under the Genevant Agreement.

•

Genevant is entitled to receive payments from the Company upon the achievement of certain milestones, including potential clinical milestone payments of up to $13.5 million, potential regulatory and development milestone paymentsof up to $27.0 million, and potential commercial milestone payments up to an aggregate total of $57.0 million.

•

Genevant is eligible to receive royalties at percentage rates in the mid-single-digits, based on future annual net sales of licensed products within the scope of the Genevant Agreement.

As of December 31, 2024, one development milestone of $1.0 million had been achieved. In January 2025, the Company announced dosing of the first participants in its Phase 1/2a REWRITE clinical program investigating KRRO-110 as a treatment for AATD, which triggered the second payment of a $1.5 million development milestone. The Company recorded $1.9 millionand $3.0 million within research and development expense in the consolidated statement of operations and comprehensive loss during the year ended December 31, 2025 and 2024, respectively, related to the Genevant Agreement.

Novo Nordisk Agreement

On September 13, 2024, the Company entered into a research collaboration and license agreement with Novo Nordisk, pursuant to which the Company granted Novo Nordisk an exclusive worldwide license under certain intellectual property rights to research, develop, manufacture, commercialize or otherwise exploit certain licensed compounds and licensed products for an initial target in the cardiometabolic field and for a second target (to be nominated by Novo Nordisk within a specified time period as set forth in the agreement).

Under the agreement, the Company has the potential to receive up to a total of $530.0 million plus tiered royalties and cost reimbursement for the Company's performance of research and development activities for two programs. Novo Nordisk agreed to pay the Company an upfront non-refundable fee of $10.0 million for the research program with respect to the initial target, and the Company is eligible to receive an additional $10.0 million upfront nonrefundable fee for a second research program with respect to the second target (if nominated by Novo Nordisk). The Company is eligible to receive research and development and regulatory milestone payments of up to $115.0 million for the initial target and up to an additional $115.0 million for the second target (if applicable). The Company is eligible to receive commercial milestone payments of up to $140.0 million for the initial target and up to an additional $140.0 million for the second target (if applicable). In addition, Novo Nordisk agreed to pay the Company royalties for each potential licensed product developed under the agreement that are an escalating tiered, mid-single digit percentage of the annual net sales of such licensed product.

Subject to the terms of the agreement, the Company granted Novo Nordisk an exclusive, worldwide, royalty-bearing license, with the right to grant sublicenses, to use certain technology controlled by the Company for the purpose of researching, developing, manufacturing, commercializing or otherwise exploiting certain licensed compounds and licensed products that contain such licensed compounds, for all uses and indications, including prophylactic, diagnostic, therapeutic, curative, management, mitigation and preventative uses. During the term of the agreement and a two-year post-termination period and on a per target basis, the Company will not be permitted to research, develop, manufacture, commercialize, or otherwise exploit outside of the collaboration, any product targeting such target.

Under the agreement, the Company is responsible for certain research and development activities with respect to licensed compounds and licensed products directed against the initial target and the second target (if nominated by Novo Nordisk), and the Company is eligible to receive cost reimbursement from Novo Nordisk for its performance of such research and development activities under the agreement with respect to such target(s). Novo Nordisk may undertake subsequent worldwide development, manufacturing, marketing and commercialization of the licensed products directed against the initial target and the second target (if applicable).

Unless earlier terminated, the agreement has a term that continues, on a per licensed product and per country basis, until the later of (i) the expiration of the last valid patent claim controlled or invented by us that covers the composition of matter of such licensed product’s licensed compound in such country, and (ii) 10 years after the first reimbursed sale of such licensed product in such country. Novo Nordisk has the right to terminate the agreement without cause in its entirety or on a per research program or per licensed product basis. The agreement may also be terminated by either party based on an uncured material breach by the other party or the bankruptcy of the other party. Upon termination of the agreement due to Novo Nordisk’s actions, the license granted by the Company to Novo Nordisk to develop, manufacture, commercialize or otherwise exploit the licensed compounds and licensed products will automatically terminate with respect to the terminated research program or terminated licensed product, as applicable. Upon termination of the agreement due to the Company's actions, Novo Nordisk may choose to either have the license granted by the Company to Novo Nordisk to develop, manufacture, commercialize or otherwise exploit the licensed compounds and licensed products terminate or continue with respect to the terminated research program or terminated licensed product.

In October 2024, the Company received an upfront nonrefundable payment of $10.0 million from Novo Nordisk and expected to receive approximately $29.5 million in cost reimbursement through 2026 to fund the related research and development activities related to the first product candidate, or program target.

The Company assessed this arrangement in accordance with ASC 606 and concluded that the contract counterparty, Novo Nordisk, is a customer. The Company determined that the research services and the exclusive licenses granted under the collaboration agreement for the initial target are not distinct and, therefore, the Company accounts for the research services and exclusive licenses as a single performance obligation. Additionally, the Company concluded that Novo Nordisk’s option to select a second target does not give rise to a material right or performance obligation until the additional target is selected due to the additional services being priced at standalone selling price. The Company recognizes revenue related to the combined license and research services performance obligation over time using the input method. Under the input method, the extent of progress towards completion is measured based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligation, which the Company believes best measures its progress towards satisfying the combined performance obligation. A cost-based input method of revenue recognition requires management to make estimates of costs to complete the performance obligation. In making such estimates, judgment is required to evaluate assumptions related to cost estimates.

Effective November 11, 2025, the Company and Novo Nordisk entered into an amendment to the research collaboration and license agreement under which the Company and Novo Nordisk agreed to pause the research collaboration and license agreement for 12 months (the “hold period”), effective as of the date of the amendment. During the hold period, the parties agreed that all research and development activities and corresponding obligations under the agreement will be suspended without any liability or payment obligation for either party. The Company also agreed to promptly wind-down its research and development activities in connection with the license agreement and Novo Nordisk agreed to reimburse the Company for certain wind-down costs associated with the hold period.

As of December 31, 2025, the total transaction price was determined to be $40.0 million based on the $10.0 million upfront nonrefundable payment and $30.0 million of estimated research services for the first program target. During the years ended December 31, 2025 and 2024, the Company recognized total collaboration revenue of $6.4 million and $2.3 million, respectively. In November 2025, the Company agreed to a 12 month pause on such collaboration with Novo Nordisk, and accordingly, the Company is expected to recognize revenue through 2028.

The Company had $0.0 million of current deferred revenue and $7.8 million of noncurrent deferred revenue as of December 31, 2025, based on the period the services are expected to be performed and/or related costs to be incurred. The Companyhad $1.0 million of current accounts receivable as of December 31, 2025.

The Company will assess the probability of achieving the milestones and include them in the transaction price when they are deemed probable. Royalties and commercial sale milestones will be recognized when the subsequent sales occur based on the sales or usage-based royalty exception.

13. Commitments and Contingencies

Leases

The Company is party to an operating lease for 50,453 square feet of office and laboratory space at 60 First Street, Cambridge, Massachusetts (the “60 First Street Lease”). In May 2023, the Company obtained control over the space and the Company recognized the operating lease right-of-use asset and the operating lease liability of $26.8 million on the commencement date of the lease. The total rental payments over the 11 year lease are expected to be $62.1 million, including rent credits and other lease incentives per the terms of the lease. Specifically, the 60 First Street Lease provides the Company with a tenant improvement allowance of $13.1 million. The Company utilized full amount of the $13.1 million tenant improvement allowance as of December 31, 2024. The lease has a remaining term of approximately nine years. The Company has an option to extend the lease for an additional period of five years with the rent during the option period being the then fair market rent.

The maturity of undiscounted payments due under lease liabilities and the present value of those liabilities as of December 31, 2025 were as follows (in thousands):

As of December 31, 2025, the weighted average remaining lease term was 8.3 years and the weighted average incremental borrowing rate used to determine the operating lease liability was 11.2%.

The Company combines the lease and non-lease components of fixed costs in its lease arrangements as a single lease component. Variable costs, such as utilities and maintenance costs, are not included in the measurement of ROU assets and lease liabilities, but rather are expensed when the event determining the amount of variable consideration to be paid occurs.

The following table summarizes the effect of lease costs in the Company’s consolidated statement of operations and comprehensive loss of its operating leases (in thousands):

During the fourth quarter of 2025, the Company recorded a non-cash, long-lived asset impairment charge of $15.0 million related to its operating ROU asset. See Note 3 for further discussion of the impairment charge.

Legal Contingencies

The Company accrues a liability for legal contingencies when it believes that it is both probable that a liability has been incurred and that the Company can reasonably estimate the amount of the loss. The Company reviews these accruals and adjusts them to reflect ongoing negotiations, settlements, rulings, advice of legal counsel and other relevant information. To the extent new information is obtained and the views on the probable outcomes of claims, suits, assessments, investigations or legal proceedings change, changes in the Company’s accrued liabilities would be recorded in the period in which such determination is made.

In addition, in accordance with the relevant authoritative guidance, for any matters in which the likelihood of material loss is at least reasonably possible, the Company will provide disclosure of the possible loss or range of loss. If a reasonable estimate cannot be made, however, the Company will provide disclosure to that effect. The Company expenses legal costs as they are incurred.

The Company was not subject to any material legal proceedings or claims as of December 31, 2025.

Indemnifications

The Company indemnifies each of its officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at the Company’s request in such capacity, as permitted under Delaware law and in accordance with the Company’s amended and restated certificate of incorporation and bylaws. The term of the indemnification period lasts as long as an officer or director may be subject to any proceeding arising out of acts or omissions of such officer or director in such capacity.

The maximum amount of potential future indemnification is unlimited; however, the Company currently holds director and officer liability insurance. This insurance allows the transfer of risk associated with the Company’s exposure and may enable the Company to recover a portion of any future amounts paid. The Company believes that the fair value of these potential indemnification obligations is minimal. Accordingly, the Company has not recognized any liabilities relating to these obligations for any period presented.

14. 401(k) Savings Plan

The Company has a defined-contribution savings plan under Section 401(k) of the IRC (the “401(k) Plan”). The 401(k) Plan covers all employees who meet defined minimum age and service requirements and allows participants to defer a portion of their annual compensation, subject to statutory limitations. Effective in 2025, the Company makes an employer non-elective safe harbor contribution of 3%of the participant’s salary, subject to employer match limitations under the IRC. As such, the Company made $0.5 million and $0.6 million of matching contributions to the 401(k) Plan during the year ended December 31, 2025 and December 31, 2024, respectively.

15. Net Loss per Share

The following common stock equivalents have been excluded from the calculation of diluted net loss per share because their effect would be anti-dilutive:

16. Restructuring

In May 2025, the Company implemented a strategic plan to streamline its operations, including a reduction in the Company’s workforce by approximately 20%. On November 12, 2025, the Company implemented a strategic restructuring to extend cash runway, including a reduction in the Company’s workforce by approximately 34%.

During the year ended December 31, 2025, the Company recorded one-time restructuring charges of $1.2 million and $2.4 million related to the May 2025 and November 2025 workforce reductions, respectively, including employee severance, benefits and related termination costs and are included under the caption “Restructuring charge” in the Company’s consolidated statement of operations and comprehensive loss. During the year ended December 31, 2025, all activities related to the May 2025 workforce reduction were completed. The remaining payments related to the November 2025 workforce reduction are expected to be paid by the third quarter of 2026.

Restructuring cost accruals are included under the caption “Accrued expenses and other current liabilities” in the Company's consolidated balance sheet.

The following is a summary of the activity for the May 2025 and November 2025 workforce reductions:

17. Segment Information

The Company operates and manages its business asone reportable segment andone operating segment, which is the business of discovering, developing and commercializing therapies derived from or incorporating its RNA-editing technology. The Company's chief operating decision maker ("CODM) is the chief executive officer.

The CODM assesses performance, monitors budget versus actual results, and decides how to allocate resources based on net loss that also is reported on the consolidated statements of operations and comprehensive loss. The CODM allocates resources based on the Company's available cash resources, forecasted cash flow, and expenditures on a consolidated basis, as well as an assessment of the probability of success of its research and development activities. Resource allocation decisions are informed by budgeted and forecasted expense information, along with actual expenses incurred to date. The accounting policies of the Company's single reportable segment are the same as those described in the summary of significant accounting policies. The level of disaggregation and amounts of significant segment expenses that are regularly provided to the CODM are the same as those presented in the consolidated statements of operations and comprehensive loss. Therefore, duplication of the Company’s consolidated statements of operations and comprehensive in this segment disclosure is not required.

The measure of segment assets is reported on the consolidated balance sheets as total consolidated assets. All long-lived assets are located in the United States. Long-lived assets primarily consist of property and equipment, net, operating lease right-of-use assets and long-term marketable securities.

Factors used in determining the reportable segment include the nature of the Company's operating activities, the organizational and reporting structure and the type of information reviewed by the CODM regularly to allocate resources and evaluate financial performance.

The Company does not have intra-entity sales or transfers.

18. Subsequent Events

At-The-Market_Equity Sale

In January 2026, the Company issued 501,861 shares of common stock under the at-the-market sales agreement for gross proceeds of $5.1 million, before deducting estimated offering expenses.

March 2026 Private Placement

On March 9, 2026, the Company entered into a subscription agreement with certain new and existing accredited investors to issue and sell an aggregate of 4,501,928 shares of its common stock at a purchase price of $11.11 per share and pre-funded warrants to purchase up to an aggregate 3,148,836 shares of its common stock per pre-funded warrant at a price of $11.109 per pre-funded warrant in a private placement that resulted in gross proceeds of approximately $85.0 million, before deducting placement agent fees and estimated offering expenses. The pre-funded warrants have an exercise price of $0.001 per share. The private placement closed on March 10, 2026.