Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2021

Summary of Significant Accounting Policies

2. Summary of significant accounting policies

Basis of presentation

The accompanying combined and consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America, or GAAP, and are stated in U.S. dollars. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification and Accounting Standards Updates, or ASUs, of the Financial Accounting Standards Board, or FASB. All intercompany balances and transactions have been eliminated in combination or consolidation.

Use of estimates

The preparation of the combined and consolidated financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and reported amounts of expenses during the reporting periods. Actual results could differ from those estimates. On an ongoing basis, the

Company evaluates its estimates, including those related to accrued research and development expenses, other long-lived assets, pension benefit obligation, stock- based compensation and the valuation of deferred tax assets. The Company bases its estimates using historical experience, Company forecasts and future plans, current economic conditions, and information from third-party professionals that management believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities and recorded amounts of expenses that are not readily apparent from other sources and adjusts those estimates and assumptions when facts and circumstances dictate.

Currency and currency translation

The combined and consolidated financial statements are presented in U.S. dollars, the Company’s reporting currency. The functional currency of the Company’s wholly owned subsidiary, Monte Rosa Therapeutics AG, is the U.S. dollar. Adjustments that arise from exchange rate changes on transactions denominated in a currency other than the functional currency are included in foreign currency exchange loss, net in the combined and consolidated statements of operations.

Cash, cash equivalents and restricted cash

The Company considers all highly liquid investments with original maturities at the date of purchase of three months or less to be cash equivalents. Cash and cash equivalents are stated at fair value and may include money market funds, U.S. Treasury and U.S. government-sponsored agency securities, corporate debt, commercial paper and certificates of deposit. The Company’s cash equivalents at December 31, 2021 and 2020 consist of bank demand deposits and money market fund investments.

The Company had restricted cash of $5.3 million as of December 31, 2021, primarily related to security deposits on its leases for offices in Boston, Massachusetts. The Company had restricted cash of $1.2 million as of December 31, 2020, primarily related to security deposits on its operating lease for its office in Boston, Massachusetts and funds reserved for a corporate credit card facility in Switzerland.

Concentrations of credit risk and off-balance sheet risk

Financial instruments that potentially subject the Company to a concentration of credit risk consist primarily of cash and cash equivalents. The Company has invested in cash and cash equivalents at December 31, 2021 and 2020, held in a financial institution that management believes is creditworthy. These deposits may exceed federally insured limits. The Company has not experienced any losses historically in these accounts and believes it in not exposed to significant credit risk in its cash and cash equivalents. The Company has no significant off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts, or other hedging arrangements.

Fair value of financial instruments

Assets and liabilities recorded at fair value on a recurring basis in the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows:

Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.

Level 2—Inputs (other than quoted prices included in Level 1) that are either directly or indirectly observable for the asset or liability. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active.

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value instrument.

Property and equipment

Property and equipment are stated at cost, subject to adjustments for impairments, less accumulated depreciation. Purchased assets that are not yet in service are classified as construction-in-process and no depreciation expense is recorded. Depreciation is calculated using the straight-line method over the useful life of the asset as follows:


Asset	Estimated useful life
Laboratory equipment	Five years
Computer hardware	Three years
Furniture and fixtures	Five Years
Leasehold Improvements	Shorter of useful life or remaining lease term

Maintenance and repairs that do not improve or extend the life of the respective asset are expensed as incurred. Upon disposal of an asset, the related cost and accumulated depreciation are removed from the accounts and any resulting gain or loss is included in the results of operations. Leasehold improvements are amortized over the shorter of the useful life or remaining term of the lease.

Impairment of long-lived assets

The Company evaluates whether current facts or circumstances indicate that the carrying values of its long-lived assets may not be recoverable. If such facts or circumstances are determined to exist, an estimate of the undiscounted future cash flows of these assets is compared to the carrying value the assets to determine whether impairment exists. If the assets are determined to be impaired, the loss is measured based on the difference between the fair value and carrying value of the assets. No material impairment losses were recorded during the years ended December 31, 2021 or 2020.

Research and development expenses

Research and development costs are expensed as incurred. The Company’s research and development expenses consist primarily of costs incurred for the research and development of its product candidates and include expenses incurred under agreements with consultants to conduct preclinical and non-clinical studies, costs to acquire supplies for preclinical studies, salaries and related personnel costs, including stock-based compensation, depreciation and other allocated facility-related and overhead expenses.

Accrued research and development costs

The Company records accruals for estimated costs of discovery research activities and preclinical studies. A portion of the Company’s research and development activities are conducted by third-party service providers. The financial terms of these contracts are subject to negotiation, which vary by contract and may result in payments that do not match the periods over which materials or services are provided. The Company accrues the costs incurred under the agreements based on an estimate of actual work completed in accordance with the agreements. In the event the Company makes advance payments for goods or services that will be used or rendered for future research and development activities, the payments are deferred and capitalized as a prepaid expense and recognized as expense as the goods are received or the related services are rendered. Such payments are evaluated for current or long-term classification based on when they are expected to be realized. If the Company does not identify costs that have begun to be incurred or if the Company underestimates or overestimates the level of services performed or the costs of these services, actual expenses could differ from the Company’s estimates.

Preferred stock tranche obligations

Included in the terms of the Series A and Series B Preferred Stock Purchase Agreements were certain rights, or Tranche Rights, granted to the investors who purchased the Series A and Series B Preferred. The Series A Tranche Rights gave the investor the option to purchase up to an aggregate of 15,000,000 additional shares of Series A Preferred at $1.00 per share. The Series B Tranche Rights gave investors the option to purchase up to an aggregate of 24,000,000 shares of Series B Preferred at $2.00 per share. The Company concluded that both the Series A and the Series B Tranche Rights met the definition of a freestanding financial instrument, as the Series A and Series B Tranche Rights were legally detachable and separately exercisable from the Series A and Series B Preferred. At initial recognition, the Company recorded these Series A and Series B Tranche Rights as a liability on the balance sheets at its estimated fair value. The Series A and Series B Preferred Stock Tranche Obligations are subject to remeasurement at each balance sheet date, with changes in fair value recognized in

changes in fair value of Preferred Stock Tranche Obligations on the Company’s combined and consolidated statements of operations and comprehensive loss.

Stock-based compensation

Stock-based compensation expense related to stock options granted to employees, directors and non-employees is recognized based on the grant-date estimated fair values of the awards using the Black-Scholes option pricing model, or Black-Scholes. Stock-based compensation expense related to restricted stock granted to employees and non-employees is recognized based on the grant-date fair value of the Company’s common stock. The value is recognized as expense ratably over the requisite service period, which is generally the vesting term of the award. The Company adjusts the expense for actual forfeitures as they occur. Stock-based compensation expense is classified in the accompanying combined and consolidated statements of operations based on the function to which the related services are provided.

Income taxes

The Company uses the liability method to account for income taxes. Under this method, deferred tax assets and liabilities are determined based on differences between the financial statement carrying amounts of existing assets and liabilities and their tax bases. Deferred tax assets and liabilities are measured using enacted tax rates applied to taxable income in the years in which those temporary differences are expected to be recovered or settled. A valuation allowance is established when necessary to reduce deferred tax assets to the amount expected to be realized.

The Company assesses the likelihood of deferred tax assets being realized. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. In assessing the realizability of deferred tax assets, the Company considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which the temporary differences representing net future deductible amounts become deductible.

The Company files U.S. federal and state income tax returns, as well as Swiss income tax returns. The Company’s tax positions are subject to audit. Financial statement effects of uncertain tax positions are recognized when it is more likely than not, based on the technical merits of the position, that it will be sustained upon examination. The Company evaluates uncertain tax positions on a regular basis. The evaluations are based on a number of factors, including changes in facts and circumstances, changes in tax law, correspondence with tax authorities during the course of the audit, and effective settlement of audit issues. Interest and penalties related to unrecognized tax benefits are included within the provision for income tax. To date, the Company has not been subject to any interest and penalties.

Defined pension benefit obligation

The Company maintains a mandatory pension for its employees in Switzerland through affiliation with the Swiss Life Collective BVG Foundation. All benefits in accordance with the regulations are reinsured in their entirety with Swiss Life Ltd within the framework of the corresponding contract. This plan is considered to be a defined benefit plan under GAAP.

The Company recognizes an asset for the plan’s overfunded status or a liability for the plan’s underfunded status in its consolidated balance sheets. Additionally, the Company measures the plan’s assets and obligations that determine its funded status as of the end of the year and recognizes the change in the funded status within the combined and consolidated statements of operations and comprehensive loss.

The Company uses an actuarial valuation to determine its pension benefit costs and credits. The amounts calculated depend on a variety of key assumptions, including discount rates and expected return on plan assets. Details of the assumptions used to determine the net funded status are described in Note 11. The Company’s pension plan assets are assigned to their respective levels in the fair value hierarchy in accordance with the valuation principles described in the Fair Value of Financial Instruments section above.

Segments

Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the chief operating decision maker, or CODM, in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its chief executive officer. The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions.

Comprehensive loss

Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. The Company’s other comprehensive loss includes adjustments to unrecognized pension benefit costs for Monte Rosa Therapeutics AG. For the years ended December 31, 2021 and 2020, the Company incurred other comprehensive loss of $1.0 million and $1.1 million, respectively.

Recently issued accounting pronouncements

The Company has elected to use the extended transition period for complying with new or revised accounting standards as available under the Jumpstart Our Business Startups Act (JOBS Act).

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), as amended, or ASU 2016-02, with guidance regarding the accounting for and disclosure of leases. The update requires lessees to recognize the liabilities related all leases, including operating leases, with a term greater than 12 months on the balance sheet. This update also requires lessees and lessors to disclose key information about their leasing transactions. In July 2018, the FASB issued ASU No. 2018-10 and 2018-11, which further clarifies the application of the guidance issued under ASU No. 2016-02 and provides updates to transition methods and practical expedients. ASU 2018-11 provides optional transition method which allows entities to adopt ASC 842 without restating prior periods. This standard is effective for annual reporting periods beginning after December 15, 2021, and interim periods within annual periods beginning after December 15, 2022.

The Company has completed its initial assessment of the impact of the new leasing standard on the Company's financial statements and internal controls, including its evaluation of key policy elections. The Company intends to adopt the new standard and related amendments under the modified retrospective approach as of January 1, 2022. Under this method, the Company is allowed to record a cumulative effect adjustment to the opening balance sheet of retained earnings in the period of adoption and not restate prior periods. Additionally, the Company expects to elect the transitional practical expedients such that the Company will not reassess whether contracts are leases and will retain lease classification and initial direct costs for leases existing prior to the adoption of the new standard. The Company also expects to make the following transitional practical expedients elections: (1) elect the short term lease exception, (2) not elect hindsight and (3) elect to not separate its nonlease components for its real estate leases. While substantially complete, the Company is still in the process of finalizing its evaluation of the effect of ASC 842 on the Company’s financial statements, disclosures, and internal controls. The Company estimates its total assets and total liabilities on the consolidated balance sheet will increase by approximately $6.0 million to $8.0 million due to the recognition of right-of-use assets and lease liabilities upon adoption, net of the impact of eliminating existing deferred rent liabilities related to its leasing arrangements. This estimated range is based on the Company's current lease portfolio but could be impacted by changes to the lease portfolio, including the total number of leases, lease commencement and end dates and lease termination expectations, as well as changes in anticipated lease incremental borrowing rates.

In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes, or ASU 2019-12. ASU 2019-12 eliminates certain exceptions related to the approach for intra-period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. It also clarifies and simplifies other aspects of the accounting for income taxes. This guidance is effective for fiscal years beginning after December 15, 2021. This impact of adopting ASU 2019-12 will not have a material impact on the consolidated financial statements.

In June 2016, the FASB issued Accounting Standards Update No. 2016-13, Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments. ASU 2016-13 requires measurement and recognition of expected credit losses for financial assets. In April 2019, the FASB issued clarification to ASU 2016-13 within ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments-Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments, or ASU 2016-13. The guidance is effective for fiscal years beginning after December 15, 2022. The Company is currently assessing the potential impact of adopting ASU 2016-13 on its financial statements and disclosures.

In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging Contracts in Entity s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity. ASU 2020-06 will simplify the accounting for convertible instruments by reducing the number of accounting models for convertible debt instruments and convertible preferred stock. Limiting the accounting models results in fewer embedded conversion features being separately recognized from the host contract as compared with current GAAP. Convertible instruments that

continue to be subject to separation models are (i) those with embedded conversion features that are not clearly and closely related to the host contract, that meet the definition of a derivative, and that do not qualify for a scope exception from derivative accounting and (ii) convertible debt instruments issued with substantial premiums for which the premiums are recorded as paid-in capital. ASU 2020-06 also amends the guidance for the derivatives scope exception for contracts in an entity’s own equity to reduce form-over-substance-based accounting conclusions. ASU 2020-06 will be effective for the Company beginning after December 15, 2023. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. The Company is currently assessing the impact adoption of ASU 2020-06 will have on the financial statements and disclosures.