Summary of Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2025
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates—The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. The Company bases its estimates and judgments on historical experience and on various other assumptions. The amounts of assets and liabilities reported in the Company's balance sheets and the amounts of revenues and expenses reported for each period presented are affected by estimates and assumptions, which are used for, but not limited to, the accounting for revenue allowances, stock-based compensation, income taxes, loss contingencies, acquisition related intangibles including in process research and development (IPR&D) and goodwill, fair value of contingent consideration, the revenue interest purchase agreement (the Royalty Financing Agreement), and accounting for R&D costs. Actual results could differ from those estimates.
Concentration of Credit Risk	Concentration of Credit Risk—Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents and marketable securities. The Company places its cash equivalents and marketable securities with high credit-quality financial institutions and may invest its investments in US treasury securities, mutual funds and government agency bonds. The Company has established guidelines relative to credit ratings and maturities that seek to maintain safety and liquidity. The Company is exposed to risks associated with extending credit to customers related to the sale of products. The Company does not require collateral to secure amounts due from its customers. The Company uses an expected loss methodology to calculate allowances for trade receivables. The Company's measurement of expected credit losses is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. The Company does not currently have a material allowance for uncollectible trade receivables.
Finite-lived Intangible Assets and Impairment Assessment	Finite-lived Intangible Assets—Finite-lived intangible assets are measured at their respective fair values on the date they were recorded. The fair values assigned to the Company's intangible assets are based on reasonable estimates and assumptions given available facts and circumstances. See Note 6 - Intangibles, Net and Goodwill for further details. Impairment Assessment—The Company reviews the recoverability of its finite-lived intangible assets and long-lived assets for indicators of impairments. Events or circumstances that may require an impairment assessment include negative clinical trial results, a significant decrease in the market price of the asset, or a significant adverse change in legal factors or the manner in which the asset is used. If such indicators are present, the Company assesses the recoverability of affected assets by determining if the carrying value of such assets is less than the sum of the undiscounted future cash flows of the assets. If such assets are found to not be recoverable, the Company measures the amount of the impairment by comparing the carrying value of the assets to the fair value of the assets.
Business Combinations and Asset Acquisitions	Business Combinations and Asset Acquisitions—The Company evaluates acquisitions of assets and other similar transactions to assess whether or not the transaction should be accounted for as a business combination or asset acquisition by first applying a screen to determine if substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or group of similar identifiable assets. If the screen is met, the transaction is accounted for as an asset acquisition. If the screen is not met, further determination is required as to whether or not the Company has acquired inputs and processes that have the ability to create outputs, which would meet the requirements of a business. If determined to be a business combination, the Company accounts for the transaction under the acquisition method of accounting as indicated in ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business, which requires the acquiring entity in a business combination to recognize the fair value of all assets acquired, liabilities assumed, and any non-controlling interest in the acquiree and establishes the acquisition date as the fair value measurement point. Accordingly, the Company recognizes assets acquired and liabilities assumed in business combinations, including contingent assets and liabilities, and non-controlling interest in the acquiree based on the fair value estimates as of the date of acquisition. In accordance with ASC 805, Business Combinations, the Company recognizes and measures goodwill as of the acquisition date, as the excess of the fair value of the consideration paid over the fair value of the identified net assets acquired. The consideration for the Company’s business acquisitions may include future payments that are contingent upon the occurrence of a particular event or events. The obligations for such contingent consideration payments are recorded at fair value on the acquisition date. The contingent consideration obligations are then evaluated each reporting period. Changes in the fair value of contingent consideration, other than changes due to payments, are recognized as a gain or loss and recorded within change in the fair value of deferred and contingent consideration liabilities in the consolidated statements of comprehensive loss. If determined to be an asset acquisition, the Company accounts for the transaction under ASC 805-50, which requires the acquiring entity in an asset acquisition to recognize assets acquired and liabilities assumed based on the cost to the acquiring entity on a relative fair value basis, which includes transaction costs in addition to consideration given. No gain or loss is recognized as of the date of acquisition unless the fair value of non-cash assets given as consideration differs from the assets’ carrying amounts on the acquiring entity’s books. Consideration transferred that is non-cash will be measured based on either the cost (which shall be measured based on the fair value of the consideration given) or the fair value of the assets acquired and liabilities assumed, whichever is more reliably measurable. Goodwill is not recognized in an asset acquisition and any excess consideration transferred over the fair value of the net assets acquired is allocated to the identifiable assets based on relative fair values. If the in-licensed agreement for IPR&D does not meet the definition of a business and the assets have not reached technological feasibility and therefore have no alternative future use, the Company expenses payments made under such license agreements as acquired IPR&D expense within R&D expense in its consolidated statements of comprehensive loss. Contingent consideration payments in asset acquisitions are recognized when the contingency is resolved and the consideration is paid or becomes payable, unless the contingent consideration meets the definition of a derivative, in which case the amount becomes part of the basis in the asset acquired. None of the Company's contingent consideration met the definition of a derivative as of June 30, 2025. Upon recognition of the contingent consideration payment, the amount is included in the cost of the acquired asset or group of assets.
Indefinite-lived Intangible Assets	Indefinite-lived Intangible Assets—Indefinite-lived intangible assets consist of IPR&D. IPR&D acquired directly in a transaction other than a business combination is capitalized if the projects will be further developed or have an alternative future use; otherwise, they are expensed. The fair values of IPR&D project assets acquired in business combinations are capitalized. The Company generally utilizes the Multi-Period Excess Earning Method to determine the estimated fair value of the IPR&D assets acquired in a business combination. The projections used in this valuation approach are based on many factors, such as relevant market size, patent protection, and expected pricing and industry trends. The estimated future net cash flows are then discounted to the present value using an appropriate discount rate. These assets are treated as indefinite-lived intangible assets until completion or abandonment of the projects, at which time the assets are amortized over the remaining useful life or written off, as appropriate. Intangible assets with indefinite lives, including IPR&D, are tested for impairment if impairment indicators arise and, at a minimum, annually. However, an entity is permitted to first assess qualitative factors to determine if a quantitative impairment test is necessary. Further testing is only required if the entity determines, based on the qualitative assessment, that it is more likely than not that an indefinite-lived intangible asset’s fair value is less than its carrying amount. The indefinite-lived intangible asset impairment test consists of a one-step analysis that compares the fair value of the intangible asset with its carrying amount. If the carrying amount of an intangible asset exceeds its fair value, an impairment loss is recognized in an amount equal to that excess. The Company considers many factors in evaluating whether the value of its intangible assets with indefinite lives may not be recoverable, including, but not limited to, expected growth rates, the cost of equity and debt capital, general economic conditions, the Company’s outlook and market performance of the Company’s industry and recent and forecasted financial performance. The Company performs a qualitative test for its indefinite-lived intangible assets annually as of October 1. During the six months ended June 30, 2025, the Company concluded that no impairment exists.
Goodwill	Goodwill—Goodwill represents the amount of consideration paid in excess of the fair value of net assets acquired as a result of the Company’s business acquisitions accounted for using the acquisition method of accounting. Goodwill is not amortized and is subject to impairment testing at a reporting unit level on an annual basis or when a triggering event occurs that may indicate the carrying value of the goodwill is impaired. An entity is permitted to first assess qualitative factors to determine if a quantitative impairment test is necessary. Further testing is only required if the entity determines, based on the qualitative assessment, that it is more likely than not that the fair value of the reporting unit is less than its carrying amount. As of June 30, 2025, the Company continues to operate as one reporting unit. The Company performs an impairment test for goodwill annually as of October 1.
Leases	Leases—A lease is a contract, or part of a contract, that conveys the right to control the use of explicitly or implicitly identified property, plant or equipment in exchange for consideration. Control of an asset is conveyed to the Company if the Company obtains the right to obtain substantially all of the economic benefits of the asset or the right to direct the use of the asset. The Company recognizes right-of-use (ROU) assets and lease liabilities at the lease commencement date based on the present value of future, fixed lease payments over the term of the arrangement. ROU assets are amortized on a straight-line basis over the term of the lease or are amortized based on consumption, if this approach is more representative of the pattern in which benefit is expected to be derived from the underlying asset. Lease liabilities accrete to yield and are reduced at the time when the lease payment is payable to the vendor. Variable lease payments are recognized at the time when the event giving rise to the payment occurs and are recognized in the consolidated statements of comprehensive loss in the same line item as expenses arising from fixed lease payments. Leases are measured at present value using the rate implicit in the lease or, if the implicit rate is not determinable, the lessee's incremental borrowing rate. As the implicit rate is not typically available, the Company uses its incremental borrowing rate based on the information available at the lease commencement date to determine the present value of future lease payments. The incremental borrowing rate approximates the rate the Company would pay to borrow on a collateralized basis over a similar term an amount equal to the lease payments.
Debt Issuance Costs	Debt Issuance Costs—Debt issuance costs are amortized to interest expense using the effective interest rate method over the term of the debt. Unamortized debt issuance costs paid to the lender and third parties are reflected as a discount to the debt in the consolidated balance sheets. Unamortized debt issuance costs associated with extinguished debt are expensed in the period of the extinguishment.
Foreign Currency	Foreign Currency—The Company has operations in the US, France, Germany, Ireland, Italy, the Netherlands, Switzerland, the UK, and Japan. The results of the Company's non-US dollar based functional currency operations are translated to US dollars at the average exchange rates during the period. Assets and liabilities are translated at the exchange rate prevailing at the balance sheet date. Equity is translated at the prevailing exchange rate at the date of the equity transaction. Translation adjustments are included in total shareholders' equity, as a component of accumulated other comprehensive gain (loss). The Company realizes foreign currency transaction gains and losses in the normal course of business based on movements in the applicable exchange rates. These gains and losses are included as a component of other income (expense), net.
Inventory and Cost of Product Revenues (excluding amortization of intangible assets)	Inventory and Cost of Product Revenues (excluding amortization of intangible assets)—Inventory is stated at the lower of cost and net realizable value. Inventory is sold on a first-in, first-out (FIFO) basis. The Company periodically reviews inventory for expiry and obsolescence and, if necessary, writes down accordingly. If quality specifications are not met during the manufacturing process, such inventory is written off to cost of product revenues (excluding amortization of intangible assets) in the period identified. Cost of product revenues (excluding amortization of intangible assets) consist primarily of direct and indirect costs related to the manufacturing of ARIKAYCE sold, including third-party manufacturing costs, packaging services, freight, and allocation of overhead costs, in addition to royalty expenses. Cost is determined using a standard cost method, which approximates actual cost, and assumes a FIFO flow of goods. Inventory used for clinical development purposes is expensed to R&D expense when consumed. Prior to US Food and Drug Administration (FDA) approval of new products, the Company expenses all inventory related costs in the period incurred.
Net Loss Per Share	Net Loss Per Share—Basic net loss per share is computed by dividing net loss by the weighted average number of common shares outstanding during the period. Diluted net loss per share is computed by dividing net loss by the weighted average number of common shares and other dilutive securities outstanding during the period. Potentially dilutive securities from stock options, restricted stock units (RSUs), performance stock units (PSUs) and convertible debt securities would be anti-dilutive as the Company incurred a net loss. Potentially dilutive common shares resulting from the assumed exercise of outstanding stock options and from the assumed conversion of the Company's convertible notes are determined based on the treasury stock method.
Recent Accounting Pronouncements (Not Yet Adopted)	Recent Accounting Pronouncements (Not Yet Adopted)—In December 2023, the FASB issued ASU 2023-09, Income Taxes—Improvements to Income Tax Disclosures, in order to enhance the transparency and decision usefulness of income tax disclosures. ASU 2023-09 requires greater disaggregation of income tax disclosures related to the income tax rate reconciliation and income taxes paid. The guidance is effective for fiscal years beginning after December 15, 2024. The Company is adopting this new standard for the year ending December 31, 2025. The Company is evaluating the impact of the required disclosure enhancements of ASU 2023-09 on its consolidated financial statements. In November 2024, the FASB issued ASU 2024-03, Income Statement (Subtopic 220-40)—Expense Disaggregation Disclosures, which requires disclosure of disaggregated income statement expense information about specific categories (including purchases of inventory, employee compensation, depreciation, and intangible asset amortization) in the notes to financial statements. ASU 2024-03 will be effective for fiscal years beginning after December 15, 2026 and interim periods beginning after December 15, 2027. The guidance is applied on a prospective basis, with a retrospective option, and early adoption is permitted. The Company is currently evaluating the impact of adoption of ASU 2024-03 on its consolidated financial statements.
Fair Value Measurements	The Company categorizes its financial assets and liabilities measured and reported at fair value in the financial statements on a recurring basis based upon the level of judgment associated with the inputs used to measure their fair value. Hierarchical levels, which are directly related to the amount of subjectivity associated with the inputs used to determine the fair value of financial assets and liabilities, are as follows: •Level 1—Inputs are 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) are either directly or indirectly observable for the assets or liability through correlation with market data at the measurement date and for the duration of the instrument’s anticipated life. •Level 3—Inputs reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model. Each major category of financial assets and liabilities measured at fair value on a recurring basis is categorized based upon the lowest level of significant input to the valuations. The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. Financial instruments in Level 1 generally include US treasuries and mutual funds listed in active markets. The Company's cash and cash equivalents permit daily redemption and the fair values of these investments are based upon the quoted prices in active markets provided by the holding financial institutions.
Deferred and Contingent Consideration	Deferred Consideration The deferred consideration arose from the acquisitions of Motus Biosciences, Inc. (Motus) and AlgaeneX, Inc. (AlgaeneX) (together, the Business Acquisition) in August 2021 (see Note 16 - Acquisitions). The Company was obligated to issue to Motus equityholders an aggregate of 184,433 shares of the Company’s common stock on each of the first, second and third anniversaries of the closing date, subject to certain reductions. During August 2022, August 2023, and August 2024, the Company fulfilled the payments due on the first, second and third anniversaries of the closing date by issuing 171,427 shares, 177,203 shares and 182,182 shares of the Company's common stock, respectively, after certain reductions. A valuation of the deferred consideration was performed quarterly with gains and losses included within change in fair value of deferred and contingent consideration liabilities in the consolidated statements of comprehensive loss. As the deferred consideration was settled in shares, no discount rate was applied in the fair value calculation. The deferred consideration was classified as a Level 2 recurring liability as its valuation utilized an input, the Insmed share price, which is a directly observable input at the measurement date and for the duration of the liabilities' anticipated lives. There was no remaining deferred consideration as of December 31, 2024. Contingent Consideration The contingent consideration liabilities arose from the Business Acquisition in August 2021 (see Note 16 - Acquisitions). The contingent consideration liabilities consist of developmental and regulatory milestones, a priority review voucher milestone, and net sales milestones. Upon the achievement of certain development and regulatory milestone events, the Company is obligated to issue to Motus equityholders up to 5,348,572 shares of the Company's common stock in the aggregate and AlgaeneX equityholders up to 368,867 shares of the Company's common stock in the aggregate. The fair value of the development and regulatory milestones are estimated utilizing a probability-adjusted approach. At June 30, 2025, the weighted average probability of success was 42%. The development and regulatory milestones, if achieved, will be settled in shares of the Company's common stock. As such, there is no discount rate applied in the fair value calculation. If the Company were to receive a priority review voucher, the Company would be obligated to pay to the Motus equityholders a portion of the value of the priority review voucher, subject to certain reductions. The potential payout will be either 50% of the after tax net proceeds received by the Company from a sale of the priority review voucher or 50% of the average of the sales prices for the last three publicly disclosed priority review voucher sales, less certain adjustments. The fair value of the priority review voucher milestone is estimated utilizing a probability-adjusted discounted cash flow approach. This obligation will be settled in cash. On December 20, 2024, the FDA's priority review voucher program expired. As of June 30, 2025 and December 31, 2024, the Company determined that the likelihood of receiving a priority review voucher was remote and the milestone had no fair value. The contingent consideration liabilities for net sales milestones were valued using an option pricing model with Monte Carlo simulation. As of June 30, 2025, the fair value of these net sales milestones were deemed immaterial to the overall fair value of the contingent consideration. The contingent consideration liabilities have been classified as a Level 3 recurring liability as its valuation requires substantial judgment and estimation of factors that are not currently observable in the market. If different assumptions were used for the inputs to the valuation approach, the estimated fair value could be significantly different than the fair value the Company determined. Contingent consideration expected to be settled within twelve months or less is classified as a current liability within accounts payable and accrued liabilities. Contingent consideration expected to be settled in more than twelve months is classified as a non-current liability. As of June 30, 2025, the fair value of the current and non-current contingent consideration was $65.7 million and $180.5 million, respectively.
Product Revenues, Net	In accordance with ASC 606, Revenue from Contracts with Customers, the Company recognizes revenue when a customer obtains control of promised goods or services, in an amount that reflects the consideration the Company expects to receive in exchange for the goods or services provided. To determine revenue recognition for arrangements within the scope of ASC 606, the Company performs the following five steps: (1) identify the contracts with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when or as the entity satisfies a performance obligation. At contract inception, the Company assesses the goods or services promised within each contract to determine which are performance obligations and to assess 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. For all contracts that fall into the scope of ASC 606, the Company has identified one performance obligation: the sale of ARIKAYCE to its customers. The Company has not incurred or capitalized any incremental costs associated with obtaining contracts with customers. Product revenues, net consist of net sales of ARIKAYCE. The Company's customers in the US include specialty pharmacies and a specialty distributor. In December 2020, the Company began recognizing product revenue from commercial sales of ARIKAYCE in Europe. In July 2021, the Company began recognizing product revenue from commercial sales of ARIKAYCE in Japan. Globally, product revenues are recognized once the Company performs and satisfies all five steps of the revenue recognition criteria described above.

Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2025

Use of Estimates—The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. The Company bases its estimates and judgments on historical experience and on various other assumptions. The amounts of assets and liabilities reported in the Company's balance sheets and the amounts of revenues and expenses reported for each period presented are affected by estimates and assumptions, which are used for, but not limited to, the accounting for revenue allowances, stock-based compensation, income taxes, loss contingencies, acquisition related intangibles including in process research and development (IPR&D) and goodwill, fair value of contingent consideration, the revenue interest purchase agreement (the Royalty Financing Agreement), and accounting for R&D costs. Actual results could differ from those estimates.

Concentration of Credit Risk

Concentration of Credit Risk—Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents and marketable securities. The Company places its cash equivalents and marketable securities with high credit-quality financial institutions and may invest its investments in US treasury securities, mutual funds and government agency bonds. The Company has established guidelines relative to credit ratings and maturities that seek to maintain safety and liquidity.

The Company is exposed to risks associated with extending credit to customers related to the sale of products. The Company does not require collateral to secure amounts due from its customers. The Company uses an expected loss methodology to calculate allowances for trade receivables. The Company's measurement of expected credit losses is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. The Company does not currently have a material allowance for uncollectible trade receivables.

Finite-lived Intangible Assets and Impairment Assessment

Finite-lived Intangible Assets—Finite-lived intangible assets are measured at their respective fair values on the date they were recorded. The fair values assigned to the Company's intangible assets are based on reasonable estimates and assumptions given available facts and circumstances. See Note 6 - Intangibles, Net and Goodwill for further details.

Impairment Assessment—The Company reviews the recoverability of its finite-lived intangible assets and long-lived assets for indicators of impairments. Events or circumstances that may require an impairment assessment include negative clinical trial results, a significant decrease in the market price of the asset, or a significant adverse change in legal factors or the

manner in which the asset is used. If such indicators are present, the Company assesses the recoverability of affected assets by determining if the carrying value of such assets is less than the sum of the undiscounted future cash flows of the assets. If such assets are found to not be recoverable, the Company measures the amount of the impairment by comparing the carrying value of the assets to the fair value of the assets.

Business Combinations and Asset Acquisitions

Business Combinations and Asset Acquisitions—The Company evaluates acquisitions of assets and other similar transactions to assess whether or not the transaction should be accounted for as a business combination or asset acquisition by first applying a screen to determine if substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or group of similar identifiable assets. If the screen is met, the transaction is accounted for as an asset acquisition. If the screen is not met, further determination is required as to whether or not the Company has acquired inputs and processes that have the ability to create outputs, which would meet the requirements of a business. If determined to be a business combination, the Company accounts for the transaction under the acquisition method of accounting as indicated in ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business, which requires the acquiring entity in a business combination to recognize the fair value of all assets acquired, liabilities assumed, and any non-controlling interest in the acquiree and establishes the acquisition date as the fair value measurement point. Accordingly, the Company recognizes assets acquired and liabilities assumed in business combinations, including contingent assets and liabilities, and non-controlling interest in the acquiree based on the fair value estimates as of the date of acquisition. In accordance with ASC 805, Business Combinations, the Company recognizes and measures goodwill as of the acquisition date, as the excess of the fair value of the consideration paid over the fair value of the identified net assets acquired.

The consideration for the Company’s business acquisitions may include future payments that are contingent upon the occurrence of a particular event or events. The obligations for such contingent consideration payments are recorded at fair value on the acquisition date. The contingent consideration obligations are then evaluated each reporting period. Changes in the fair value of contingent consideration, other than changes due to payments, are recognized as a gain or loss and recorded within change in the fair value of deferred and contingent consideration liabilities in the consolidated statements of comprehensive loss.

If determined to be an asset acquisition, the Company accounts for the transaction under ASC 805-50, which requires the acquiring entity in an asset acquisition to recognize assets acquired and liabilities assumed based on the cost to the acquiring entity on a relative fair value basis, which includes transaction costs in addition to consideration given. No gain or loss is recognized as of the date of acquisition unless the fair value of non-cash assets given as consideration differs from the assets’ carrying amounts on the acquiring entity’s books. Consideration transferred that is non-cash will be measured based on either the cost (which shall be measured based on the fair value of the consideration given) or the fair value of the assets acquired and liabilities assumed, whichever is more reliably measurable. Goodwill is not recognized in an asset acquisition and any excess consideration transferred over the fair value of the net assets acquired is allocated to the identifiable assets based on relative fair values. If the in-licensed agreement for IPR&D does not meet the definition of a business and the assets have not reached technological feasibility and therefore have no alternative future use, the Company expenses payments made under such license agreements as acquired IPR&D expense within R&D expense in its consolidated statements of comprehensive loss.

Contingent consideration payments in asset acquisitions are recognized when the contingency is resolved and the consideration is paid or becomes payable, unless the contingent consideration meets the definition of a derivative, in which case the amount becomes part of the basis in the asset acquired. None of the Company's contingent consideration met the definition of a derivative as of June 30, 2025. Upon recognition of the contingent consideration payment, the amount is included in the cost of the acquired asset or group of assets.

Indefinite-lived Intangible Assets

Indefinite-lived Intangible Assets—Indefinite-lived intangible assets consist of IPR&D. IPR&D acquired directly in a transaction other than a business combination is capitalized if the projects will be further developed or have an alternative future use; otherwise, they are expensed. The fair values of IPR&D project assets acquired in business combinations are capitalized. The Company generally utilizes the Multi-Period Excess Earning Method to determine the estimated fair value of the IPR&D assets acquired in a business combination. The projections used in this valuation approach are based on many factors, such as relevant market size, patent protection, and expected pricing and industry trends. The estimated future net cash flows are then discounted to the present value using an appropriate discount rate. These assets are treated as indefinite-lived intangible assets until completion or abandonment of the projects, at which time the assets are amortized over the remaining useful life or written off, as appropriate. Intangible assets with indefinite lives, including IPR&D, are tested for impairment if impairment indicators arise and, at a minimum, annually. However, an entity is permitted to first assess qualitative factors to determine if a quantitative impairment test is necessary. Further testing is only required if the entity determines, based on the qualitative assessment, that it is more likely than not that an indefinite-lived intangible asset’s fair value is less than its carrying amount.

The indefinite-lived intangible asset impairment test consists of a one-step analysis that compares the fair value of the intangible asset with its carrying amount. If the carrying amount of an intangible asset exceeds its fair value, an impairment loss is recognized in an amount equal to that excess. The Company considers many factors in evaluating whether the value of its intangible assets with indefinite lives may not be recoverable, including, but not limited to, expected growth rates, the cost of equity and debt capital, general economic conditions, the Company’s outlook and market performance of the Company’s industry and recent and forecasted financial performance. The Company performs a qualitative test for its indefinite-lived intangible assets annually as of October 1. During the six months ended June 30, 2025, the Company concluded that no impairment exists.

Goodwill

Goodwill—Goodwill represents the amount of consideration paid in excess of the fair value of net assets acquired as a result of the Company’s business acquisitions accounted for using the acquisition method of accounting. Goodwill is not amortized and is subject to impairment testing at a reporting unit level on an annual basis or when a triggering event occurs that may indicate the carrying value of the goodwill is impaired. An entity is permitted to first assess qualitative factors to determine if a quantitative impairment test is necessary. Further testing is only required if the entity determines, based on the qualitative assessment, that it is more likely than not that the fair value of the reporting unit is less than its carrying amount. As of June 30, 2025, the Company continues to operate as one reporting unit. The Company performs an impairment test for goodwill annually as of October 1.

Leases

Leases—A lease is a contract, or part of a contract, that conveys the right to control the use of explicitly or implicitly identified property, plant or equipment in exchange for consideration. Control of an asset is conveyed to the Company if the Company obtains the right to obtain substantially all of the economic benefits of the asset or the right to direct the use of the asset. The Company recognizes right-of-use (ROU) assets and lease liabilities at the lease commencement date based on the present value of future, fixed lease payments over the term of the arrangement. ROU assets are amortized on a straight-line basis over the term of the lease or are amortized based on consumption, if this approach is more representative of the pattern in which benefit is expected to be derived from the underlying asset. Lease liabilities accrete to yield and are reduced at the time when the lease payment is payable to the vendor. Variable lease payments are recognized at the time when the event giving rise to the payment occurs and are recognized in the consolidated statements of comprehensive loss in the same line item as expenses arising from fixed lease payments.

Leases are measured at present value using the rate implicit in the lease or, if the implicit rate is not determinable, the lessee's incremental borrowing rate. As the implicit rate is not typically available, the Company uses its incremental borrowing rate based on the information available at the lease commencement date to determine the present value of future lease payments. The incremental borrowing rate approximates the rate the Company would pay to borrow on a collateralized basis over a similar term an amount equal to the lease payments.

Debt Issuance Costs

Debt Issuance Costs—Debt issuance costs are amortized to interest expense using the effective interest rate method over the term of the debt. Unamortized debt issuance costs paid to the lender and third parties are reflected as a discount to the debt in the consolidated balance sheets. Unamortized debt issuance costs associated with extinguished debt are expensed in the period of the extinguishment.

Foreign Currency

Foreign Currency—The Company has operations in the US, France, Germany, Ireland, Italy, the Netherlands, Switzerland, the UK, and Japan. The results of the Company's non-US dollar based functional currency operations are translated to US dollars at the average exchange rates during the period. Assets and liabilities are translated at the exchange rate prevailing at the balance sheet date. Equity is translated at the prevailing exchange rate at the date of the equity transaction. Translation adjustments are included in total shareholders' equity, as a component of accumulated other comprehensive gain (loss).

The Company realizes foreign currency transaction gains and losses in the normal course of business based on movements in the applicable exchange rates. These gains and losses are included as a component of other income (expense), net.

Inventory and Cost of Product Revenues (excluding amortization of intangible assets)

Inventory and Cost of Product Revenues (excluding amortization of intangible assets)—Inventory is stated at the lower of cost and net realizable value. Inventory is sold on a first-in, first-out (FIFO) basis. The Company periodically reviews inventory for expiry and obsolescence and, if necessary, writes down accordingly. If quality specifications are not met during the manufacturing process, such inventory is written off to cost of product revenues (excluding amortization of intangible assets) in the period identified.

Cost of product revenues (excluding amortization of intangible assets) consist primarily of direct and indirect costs related to the manufacturing of ARIKAYCE sold, including third-party manufacturing costs, packaging services, freight, and allocation of overhead costs, in addition to royalty expenses. Cost is determined using a standard cost method, which approximates actual cost, and assumes a FIFO flow of goods. Inventory used for clinical development purposes is expensed to R&D expense when consumed. Prior to US Food and Drug Administration (FDA) approval of new products, the Company expenses all inventory related costs in the period incurred.

Net Loss Per Share

Net Loss Per Share—Basic net loss per share is computed by dividing net loss by the weighted average number of common shares outstanding during the period. Diluted net loss per share is computed by dividing net loss by the weighted average number of common shares and other dilutive securities outstanding during the period. Potentially dilutive securities from stock options, restricted stock units (RSUs), performance stock units (PSUs) and convertible debt securities would be anti-dilutive as the Company incurred a net loss. Potentially dilutive common shares resulting from the assumed exercise of outstanding stock options and from the assumed conversion of the Company's convertible notes are determined based on the treasury stock method.

Recent Accounting Pronouncements (Not Yet Adopted)

Recent Accounting Pronouncements (Not Yet Adopted)—In December 2023, the FASB issued ASU 2023-09, Income Taxes—Improvements to Income Tax Disclosures, in order to enhance the transparency and decision usefulness of income tax disclosures. ASU 2023-09 requires greater disaggregation of income tax disclosures related to the income tax rate reconciliation and income taxes paid. The guidance is effective for fiscal years beginning after December 15, 2024. The Company is adopting this new standard for the year ending December 31, 2025. The Company is evaluating the impact of the required disclosure enhancements of ASU 2023-09 on its consolidated financial statements.

In November 2024, the FASB issued ASU 2024-03, Income Statement (Subtopic 220-40)—Expense Disaggregation Disclosures, which requires disclosure of disaggregated income statement expense information about specific categories (including purchases of inventory, employee compensation, depreciation, and intangible asset amortization) in the notes to financial statements. ASU 2024-03 will be effective for fiscal years beginning after December 15, 2026 and interim periods beginning after December 15, 2027. The guidance is applied on a prospective basis, with a retrospective option, and early adoption is permitted. The Company is currently evaluating the impact of adoption of ASU 2024-03 on its consolidated financial statements.

Fair Value Measurements

The Company categorizes its financial assets and liabilities measured and reported at fair value in the financial statements on a recurring basis based upon the level of judgment associated with the inputs used to measure their fair value. Hierarchical levels, which are directly related to the amount of subjectivity associated with the inputs used to determine the fair value of financial assets and liabilities, are as follows:

•Level 1—Inputs are 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) are either directly or indirectly observable for the assets or liability through correlation with market data at the measurement date and for the duration of the instrument’s anticipated life.

•Level 3—Inputs reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model.

Each major category of financial assets and liabilities measured at fair value on a recurring basis is categorized based upon the lowest level of significant input to the valuations. The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. Financial instruments in Level 1 generally include US treasuries and mutual funds listed in active markets. The Company's cash and cash equivalents permit daily redemption and the fair values of these investments are based upon the quoted prices in active markets provided by the holding financial institutions.

Deferred and Contingent Consideration

Deferred Consideration

The deferred consideration arose from the acquisitions of Motus Biosciences, Inc. (Motus) and AlgaeneX, Inc. (AlgaeneX) (together, the Business Acquisition) in August 2021 (see Note 16 - Acquisitions). The Company was obligated to issue to Motus equityholders an aggregate of 184,433 shares of the Company’s common stock on each of the first, second and third anniversaries of the closing date, subject to certain reductions. During August 2022, August 2023, and August 2024, the Company fulfilled the payments due on the first, second and third anniversaries of the closing date by issuing 171,427 shares, 177,203 shares and 182,182 shares of the Company's common stock, respectively, after certain reductions. A valuation of the deferred consideration was performed quarterly with gains and losses included within change in fair value of deferred and contingent consideration liabilities in the consolidated statements of comprehensive loss. As the deferred consideration was settled in shares, no discount rate was applied in the fair value calculation.

The deferred consideration was classified as a Level 2 recurring liability as its valuation utilized an input, the Insmed share price, which is a directly observable input at the measurement date and for the duration of the liabilities' anticipated lives. There was no remaining deferred consideration as of December 31, 2024.

Contingent Consideration

The contingent consideration liabilities arose from the Business Acquisition in August 2021 (see Note 16 - Acquisitions). The contingent consideration liabilities consist of developmental and regulatory milestones, a priority review voucher milestone, and net sales milestones. Upon the achievement of certain development and regulatory milestone events, the Company is obligated to issue to Motus equityholders up to 5,348,572 shares of the Company's common stock in the aggregate and AlgaeneX equityholders up to 368,867 shares of the Company's common stock in the aggregate. The fair value of the development and regulatory milestones are estimated utilizing a probability-adjusted approach. At June 30, 2025, the weighted average probability of success was 42%. The development and regulatory milestones, if achieved, will be settled in shares of the Company's common stock. As such, there is no discount rate applied in the fair value calculation.

If the Company were to receive a priority review voucher, the Company would be obligated to pay to the Motus equityholders a portion of the value of the priority review voucher, subject to certain reductions. The potential payout will be either 50% of the after tax net proceeds received by the Company from a sale of the priority review voucher or 50% of the average of the sales prices for the last three publicly disclosed priority review voucher sales, less certain adjustments. The fair value of the priority review voucher milestone is estimated utilizing a probability-adjusted discounted cash flow approach. This obligation will be settled in cash. On December 20, 2024, the FDA's priority review voucher program expired. As of June 30, 2025 and December 31, 2024, the Company determined that the likelihood of receiving a priority review voucher was remote and the milestone had no fair value.

The contingent consideration liabilities for net sales milestones were valued using an option pricing model with Monte Carlo simulation. As of June 30, 2025, the fair value of these net sales milestones were deemed immaterial to the overall fair value of the contingent consideration.

The contingent consideration liabilities have been classified as a Level 3 recurring liability as its valuation requires substantial judgment and estimation of factors that are not currently observable in the market. If different assumptions were used for the inputs to the valuation approach, the estimated fair value could be significantly different than the fair value the Company determined. Contingent consideration expected to be settled within twelve months or less is classified as a current liability within accounts payable and accrued liabilities. Contingent consideration expected to be settled in more than twelve months is classified as a non-current liability. As of June 30, 2025, the fair value of the current and non-current contingent consideration was $65.7 million and $180.5 million, respectively.

Product Revenues, Net

In accordance with ASC 606, Revenue from Contracts with Customers, the Company recognizes revenue when a customer obtains control of promised goods or services, in an amount that reflects the consideration the Company expects to receive in exchange for the goods or services provided. To determine revenue recognition for arrangements within the scope of ASC 606, the Company performs the following five steps: (1) identify the contracts with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when or as the entity satisfies a performance obligation. At contract inception, the Company assesses the goods or services promised within each contract to determine which are performance obligations and to assess 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. For all contracts that fall into the scope of ASC 606, the Company has identified one performance obligation: the sale of ARIKAYCE to its customers. The Company has not incurred or capitalized any incremental costs associated with obtaining contracts with customers.

Product revenues, net consist of net sales of ARIKAYCE. The Company's customers in the US include specialty pharmacies and a specialty distributor. In December 2020, the Company began recognizing product revenue from commercial sales of ARIKAYCE in Europe. In July 2021, the Company began recognizing product revenue from commercial sales of ARIKAYCE in Japan. Globally, product revenues are recognized once the Company performs and satisfies all five steps of the revenue recognition criteria described above.