Insmed (INSM) 10-Q9 May 242024 Q1 Quarterly reportFinancial data

Company Profile

Cover Page

Cover Page - shares	3 Months Ended
Cover Page - shares	Mar. 31, 2024	May 06, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	000-30739
Entity Registrant Name	INSMED INC
Entity Incorporation, State or Country Code	VA
Entity Tax Identification Number	54-1972729
Entity Address, Address Line One	700 US Highway 202/206
Entity Address, City or Town	Bridgewater
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	08807
City Area Code	908
Local Phone Number	977-9900
Title of 12(b) Security	Common stock, par value $0.01 per share
Trading Symbol	INSM
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		148,604,548
Entity Central Index Key	0001104506
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 595,729	$ 482,374
Marketable securities	0	298,073
Accounts receivable	37,162	41,189
Inventory	82,957	83,248
Prepaid expenses and other current assets	42,874	24,179
Total current assets	758,722	929,063
Fixed assets, net	68,660	65,384
Finance lease right-of-use assets	20,307	20,985
Operating lease right-of-use assets	17,157	18,017
Intangibles, net	62,441	63,704
Goodwill	136,110	136,110
Other assets	95,698	96,574
Total assets	1,159,095	1,329,837
Current liabilities:
Accounts payable and accrued liabilities	189,362	214,987
Current portion of long-term debt	224,194	0
Finance lease liabilities	2,695	2,610
Operating lease liabilities	4,609	8,032
Total current liabilities	420,860	225,629
Debt, long-term	939,081	1,155,313
Royalty financing agreement	156,967	155,034
Contingent consideration	63,700	84,600
Finance lease liabilities, long-term	26,320	27,026
Operating lease liabilities, long-term	13,809	11,013
Other long-term liabilities	3,166	3,145
Total liabilities	1,623,903	1,661,760
Shareholders’ equity:
Common stock, $0.01 par value; 500,000,000 authorized shares, 148,560,882 and 147,977,960 issued and outstanding shares at March 31, 2024 and December 31, 2023, respectively	1,486	1,480
Additional paid-in capital	3,138,578	3,113,487
Accumulated deficit	(3,603,236)	(3,446,145)
Accumulated other comprehensive loss	(1,636)	(745)
Total shareholders’ deficit	(464,808)	(331,923)
Total liabilities and shareholders’ deficit	$ 1,159,095	$ 1,329,837

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized shares (in shares)	500,000,000	500,000,000
Common stock, issued shares (in shares)	148,560,882	147,977,960
Common stock, outstanding shares (in shares)	148,560,882	147,977,960

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Statement of Comprehensive Income [Abstract]
Product revenues, net	$ 75,500	$ 65,214
Revenue from Contract with Customer, Product and Service [Extensible List]	Product [Member]	Product [Member]
Operating expenses:
Cost of product revenues (excluding amortization of intangible assets)	$ 17,457	$ 13,830
Cost, Product and Service [Extensible List]	Product [Member]	Product [Member]
Research and development	$ 121,083	$ 127,865
Selling, general and administrative	93,102	79,914
Amortization of intangible assets	1,263	1,263
Change in fair value of deferred and contingent consideration liabilities	(11,900)	(9,500)
Total operating expenses	221,005	213,372
Operating loss	(145,505)	(148,158)
Investment income	8,783	10,524
Interest expense	(21,042)	(20,003)
Change in fair value of interest rate swap	2,362	(1,533)
Other expense, net	(1,100)	(111)
Loss before income taxes	(156,502)	(159,281)
Provision for income taxes	589	483
Net loss	$ (157,091)	$ (159,764)
Basic net loss per share (in dollars per share)	$ (1.06)	$ (1.17)
Diluted net loss per share (in dollars per share)	$ (1.06)	$ (1.17)
Weighted average basic common shares outstanding (in shares)	148,456	136,355
Weighted average diluted common shares outstanding (in shares)	148,456	136,355
Net loss	$ (157,091)	$ (159,764)
Other comprehensive income (loss):
Foreign currency translation losses	(855)	(171)
Unrealized (loss) gain on marketable securities	(36)	498
Total comprehensive loss	$ (157,982)	$ (159,437)

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity (unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balance (in shares) at Dec. 31, 2022		135,654
Balance at Dec. 31, 2022	$ 87,951	$ 1,357	$ 2,782,416	$ (2,696,578)	$ 756
Comprehensive loss:
Net loss	(159,764)			(159,764)
Other comprehensive income (loss)	327				327
Exercise of stock options and ESPP shares (in shares)		82
Exercise of stock options and ESPP shares	1,139	$ 1	1,138
Issuance of common stock for vesting of RSUs (in shares)		193
Issuance of common stock for vesting of RSUs	1	$ 1
Issuance of common stock for asset acquisition (in shares)		500
Issuance of common stock for asset acquisition	9,250	$ 5	9,245
Stock-based compensation expense	16,443		16,443
Balance (in shares) at Mar. 31, 2023		136,429
Balance at Mar. 31, 2023	(44,653)	$ 1,364	2,809,242	(2,856,342)	1,083
Balance (in shares) at Dec. 31, 2023		147,978
Balance at Dec. 31, 2023	(331,923)	$ 1,480	3,113,487	(3,446,145)	(745)
Comprehensive loss:
Net loss	(157,091)			(157,091)
Other comprehensive income (loss)	(891)				(891)
Exercise of stock options and ESPP shares (in shares)		217
Exercise of stock options and ESPP shares	4,052	$ 2	4,050
Net proceeds from issuance of common stock (in shares)
Net proceeds from issuance of common stock	(409)		(409)
Issuance of common stock for vesting of RSUs (in shares)		366
Issuance of common stock for vesting of RSUs	4	$ 4
Stock-based compensation expense	21,450		21,450
Balance (in shares) at Mar. 31, 2024		148,561
Balance at Mar. 31, 2024	$ (464,808)	$ 1,486	$ 3,138,578	$ (3,603,236)	$ (1,636)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating activities
Net loss	$ (157,091)	$ (159,764)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	1,588	1,248
Amortization of intangible assets	1,263	1,263
Stock-based compensation expense	21,450	16,443
Amortization of debt issuance costs	1,851	1,724
Paid-in-kind interest capitalized	6,242	5,456
Royalty financing non-cash interest expense	4,822	2,615
Accretion of discount on marketable securities, net	(1,963)	0
Finance lease amortization expense	678	678
Non-cash operating lease expense	6,516	2,491
Change in fair value of deferred and contingent consideration liabilities	(11,900)	(9,500)
Change in fair value of interest rate swap	(2,362)	1,533
Changes in operating assets and liabilities:
Accounts receivable	2,955	(860)
Inventory	(598)	(1,187)
Prepaid expenses and other current assets	(19,330)	(3,199)
Other assets	333	(5,231)
Accounts payable and accrued liabilities	(32,345)	(8,841)
Other liabilities	(6,144)	(1,422)
Net cash used in operating activities	(184,035)	(146,303)
Investing activities
Purchase of fixed assets	(4,679)	(3,398)
Maturities of marketable securities	300,000	45,000
Net cash provided by investing activities	295,321	41,602
Financing activities
Proceeds from exercise of stock options and ESPP	4,052	1,139
Payments of equity issuance costs	(409)	0
Payments of finance lease principal	(621)	(320)
Payment of debt issuance costs	0	(1,218)
Net cash provided by (used in) financing activities	3,022	(399)
Effect of exchange rates on cash and cash equivalents	(953)	(29)
Net increase (decrease) in cash and cash equivalents	113,355	(105,129)
Cash and cash equivalents at beginning of period	482,374	1,074,036
Cash and cash equivalents at end of period	595,729	968,907
Supplemental disclosures of cash flow information:
Cash paid for interest	8,210	11,589
Cash paid for income taxes	1,208	1,004
Vertuis Bio, Inc.
Adjustments to reconcile net loss to net cash used in operating activities:
Vertuis acquisition	0	10,250
Adrestia acquisition	$ 0	$ 10,250

The Company and Basis of Presen

The Company and Basis of Presentation	3 Months Ended
The Company and Basis of Presentation	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
The Company and Basis of Presentation	1. The Company and Basis of Presentation Insmed is a global biopharmaceutical company on a mission to transform the lives of patients with serious and rare diseases. The Company's first commercial product, ARIKAYCE, is approved in the United States (US) as ARIKAYCE ® (amikacin liposome inhalation suspension), in Europe as ARIKAYCE Liposomal 590 mg Nebuliser Dispersion and in Japan as ARIKAYCE inhalation 590 mg (amikacin sulfate inhalation drug product). ARIKAYCE received accelerated approval in the US in September 2018 for the treatment of Mycobacterium avium complex (MAC) lung disease as part of a combination antibacterial drug regimen for adult patients with limited or no alternative treatment options in a refractory setting. In October 2020, the European Commission (EC) approved ARIKAYCE for the treatment of nontuberculous mycobacterial (NTM) lung infections caused by MAC in adults with limited treatment options who do not have cystic fibrosis (CF). In March 2021, Japan's Ministry of Health, Labour and Welfare (MHLW) approved ARIKAYCE for the treatment of patients with NTM lung disease caused by MAC who did not sufficiently respond to prior treatment with a multidrug regimen. NTM lung disease caused by MAC (which the Company refers to as MAC lung disease) is a rare and often chronic infection that can cause irreversible lung damage and can be fatal. The Company's pipeline includes clinical-stage programs, brensocatib and treprostinil palmitil inhalation powder (TPIP), as well as other early-stage research programs. Brensocatib is a small molecule, oral, reversible inhibitor of dipeptidyl peptidase 1 (DPP1), which the Company is developing for the treatment of patients with bronchiectasis and other neutrophil-mediated diseases, including chronic rhinosinusitis without nasal polyps (CRSsNP). TPIP is an inhaled formulation of the treprostinil prodrug treprostinil palmitil which may offer a differentiated product profile for pulmonary hypertension associated with interstitial lung disease (PH-ILD) and pulmonary arterial hypertension (PAH). The Company's early-stage research programs encompass a wide range of technologies and modalities, including gene therapy, artificial intelligence-driven protein engineering, protein manufacturing, RNA-end joining, and synthetic rescue. The Company was incorporated in the Commonwealth of Virginia on November 29, 1999 and its principal executive offices are located in Bridgewater, New Jersey. The Company has legal entities in the US, France, Germany, Ireland, Italy, the Netherlands, Switzerland, the United Kingdom (UK), and Japan. The accompanying unaudited interim consolidated financial statements have been prepared pursuant to the rules and regulations for reporting on Form 10-Q. Accordingly, certain information and disclosures required by accounting principles generally accepted in the US (GAAP) for complete consolidated financial statements are not included herein. The unaudited interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company's Annual Report on Form 10-K for the year ended December 31, 20 . Any references in these notes to applicable accounting guidance are meant to refer to GAAP as found in the Accounting Standards Codification (ASC) and Accounting Standards Updates (ASU) of the Financial Accounting Standards Board (FASB). The results of operations of any interim period are not necessarily indicative of the results of operations for the full year. The unaudited interim consolidated financial information presented herein reflects all normal adjustments that are, in the opinion of management, necessary for a fair statement of the financial position, results of operations and cash flows for the periods presented. All intercompany transactions and balances have been eliminated in consolidation. The Company had $595.7 million in cash and cash equivalents as of March 31, 2024 and reported a net loss of $157.1 million for the three months ended March 31, 2024. The Company has funded its operations through public offerings of equity securities, de bt financings and revenue interest financings. The Company expects to continue to incur consolidated operating losses, including losses in its US and certain international entities, while funding research and development (R&D) activities for ARIKAYCE, brensocatib, TPIP and its other pipeline programs, continuing commercialization and regulatory activities for ARIKAYCE and pre-commercial, regulatory and, if approved, commercialization activities for brensocatib, and funding other general and administrative activities. The Company expects its future cash requirements to be substantial. While the Company currently has sufficient funds to meet its financial needs for at least the next 12 months, the Company may raise additional capital in the future to fund its operations, its ongoing commercialization and clinical trial activities, and its future product candidates, and to develop, acquire, in-license or co-promote other products or product candidates, including those that address orphan or rare diseases. The source, timing and availability of any future financing or other transaction will depend principally upon continued progress in the Company’s commercial, regulatory and development activities. Any future financing will also be contingent upon market conditions. If the Company is unable to obtain sufficient additional funds when required, the Company may be forced to delay, restrict or eliminate all or a portion of its development programs or commercialization efforts.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies The Company’s complete listing of significant accounting policies is set forth in Note 2 of the notes to the consolidated financial statements in the Company's Annual Report on Form 10-K for the year ended December 31, 2023 . Selected significant accounting policies are discussed in detail below. 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, and accounting for research and development costs. Actual results could differ from those estimates. Concentration of Credit Risk —Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents. The Company places its cash equivalents 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. The following table presents the percentage of gross product revenue represented by the Company's three largest customers as of the three months ended March 31, 2024 and their respective percentages for the three months ended March 31, 2023. Three Months Ended March 31, 2024 2023 Customer A 35% 36% Customer B 34% 36% Customer C 16% 17% The Company relies on third-party manufacturers and suppliers for manufacturing and supply of its products. The inability of the suppliers or manufacturers to fulfill supply requirements of the Company could materially impact future operating results. A change in the relationship with the suppliers or manufacturers, or an adverse change in their business, could materially impact future operating results. 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 —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 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 March 31, 2024. Upon recognition of a 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 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. 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 March 31, 2024 and December 31, 2023, the Company continues to operate as one reporting unit. The Company will perform its next annual impairment testing for goodwill as of October 1, 2024. See Note 6 - Intangibles, Net and Goodwill for further details. 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 implicit borrowing rate. As the implicit rate is not typically available, the Company uses its implicit borrowing rate based on the information available at the lease commencement date to determine the present value of future lease payments. The implicit 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. See Note 9 - Leases for further details. 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 —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' deficit, as a component of accumulated other comprehensive 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 expense, net. Derivatives —In the normal course of business, the Company is exposed to the effects of interest rate changes. The Company may enter into derivative instruments, including interest rate swaps and caps, to manage or hedge interest rate risk. Derivative instruments are recorded at fair value on the balance sheet date. The Company has not elected hedge accounting treatment for the changes in the fair value of derivatives. Changes in the fair value of derivatives are recorded each period and are included in change in fair value of interest rate swap in the consolidated statements of comprehensive loss and consolidated statements of cash flows. 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. 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 (RS), 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. The following table sets forth the reconciliation of the weighted average number of common shares used to compute basic and diluted net loss per share for the three months ended March 31, 2024 and 2023: Three Months Ended March 31, 2024 2023 Numerator: Net loss $ (157,091) $ (159,764) Denominator: Weighted average common shares used in calculation of basic net loss per share: 148,456 136,355 Effect of dilutive securities: Common stock options — — RS and RSUs — — PSUs — — Convertible debt securities — — Weighted average common shares outstanding used in calculation of diluted net loss per share 148,456 136,355 Net loss per share: Basic and diluted $ (1.06) $ (1.17) The following potentially dilutive securities have been excluded from the computations of diluted weighted average common shares outstanding as of March 31, 2024 and 2023, respectively, as their effect would have been anti-dilutive (in thousands): As of March 31, 2024 2023 Common stock options 24,098 19,156 Unvested RS and RSUs 3,059 2,058 PSUs 666 671 Convertible debt securities 23,438 23,438 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. ASU 2023-09 will be effective for fiscal years beginning after December 15, 2024. The Company is currently evaluating the impact of adoption of ASU 2023-09 on its consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
Fair Value Measurements	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. 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. The following table shows assets and liabilities that are measured at fair value on a recurring basis and their carrying value (in millions): As of March 31, 2024 Fair Value Carrying Value Level 1 Level 2 Level 3 Assets Cash and cash equivalents $ 595.7 $ 595.7 $ — $ — Collateral for interest rate swap $ 6.0 $ 6.0 $ — $ — Liabilities Interest rate swap $ (1.2) $ — $ (1.2) $ — Deferred consideration $ 5.0 $ — $ 5.0 $ — Contingent consideration $ 73.4 $ — $ — $ 73.4 As of December 31, 2023 Fair Value Carrying Value Level 1 Level 2 Level 3 Assets Cash and cash equivalents $ 482.4 $ 482.4 $ — $ — Marketable securities $ 298.1 $ 298.1 $ — $ — Collateral for interest rate swap $ 6.0 $ 6.0 $ — $ — Liabilities Interest rate swap $ 1.2 $ — $ 1.2 $ — Deferred consideration $ 5.7 $ — $ 5.7 $ — Contingent consideration $ 84.6 $ — $ — $ 84.6 During the three months ended March 31, 2024, $300.0 million of marketable securities, consisting of US Treasury Notes, matured. The Company recognizes transfers between levels within the fair value hierarchy, if any, at the end of each quarter. The collateral for interest rate swap and the interest rate swap are recorded in other assets and accounts payable and accrued liabilities, respectively, in the consolidated balance sheet as of March 31, 2024 and December 31, 2023. The collateral for interest rate swap is cash, a Level 1 asset. The interest rate swap is a Level 2 liability as it uses observable inputs other than quoted market prices in an active market. There were no transfers in or out of Level 1, Level 2 or Level 3 during the three months ended March 31, 2024. As of March 31, 2024, the Company held no available-for-sale securities. Marketable securities maturing in one year or less are classified as current assets and marketable securities maturing in more than one year are classified as non-current assets. The Company reviews the status of each security quarterly to determine whether an other-than-temporary impairment has occurred. In making its determination, the Company considers a number of factors, including: (1) the significance of the decline; (2) whether the security was rated below investment grade; (3) failure of the issuer to make scheduled interest or principal payments; and (4) the Company's ability and intent to retain the investment for a sufficient period of time for it to recover. The Company has determined that there were no other-than-temporary impairments during the three months ended March 31, 2024. Deferred Consideration The deferred consideration arose from the acquisitions of Motus Biosciences, Inc. (Motus) and AlgaeneX, Inc. (AlgaeneX) (the Business Acquisition) in August 2021. The Company is 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 and August 2023, the Company fulfilled the payments due on the first and second anniversaries of the closing date by issuing 171,427 shares and 177,203 shares of the Company's common stock, respectively, after certain reductions. A valuation of the deferred consideration is 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 is settled in shares, there is no discount rate applied in the fair value calculation. The deferred consideration has been classified as a Level 2 recurring liability as its valuation utilizes 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. Deferred consideration expected to be settled within twelve months or less is classified as a current liability within accounts payable and accrued liabilities. As of March 31, 2024, the fair value of deferred consideration included in accounts payable and accrued liabilities was $5.0 million. The following observable input was used in the valuation of the deferred consideration as of March 31, 2024: Fair Value as of March 31, 2024 (in millions) Observable Input Input Value Deferred consideration $5.0 Insmed share price as of March 31, 2024 $27.13 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 in the aggregate and AlgaeneX equityholders up to 368,867 shares in the aggregate. The fair value of the development and regulatory milestones are estimated utilizing a probability-adjusted approach. At March 31, 2024, the weighted average probability of success was 42%. The development and regulatory milestones 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 is 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. The contingent consideration liabilities for net sales milestones were valued using an option pricing model with Monte Carlo simulation. As of March 31, 2024, 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 March 31, 2024, the fair value of the current and non-current contingent consideration was $9.7 million and $63.7 million, respectively. A valuation of the contingent consideration liabilities is performed quarterly with gains and losses included within change in fair value of contingent consideration liabilities in the consolidated statements of comprehensive loss. The following significant unobservable inputs were used in the valuation of the development and regulatory milestones and the priority review voucher milestone as of March 31, 2024: Fair Value as of March 31, 2024 (in millions) Valuation Technique Unobservable Inputs Values Development and regulatory milestones $65.5 Probability-adjusted Probabilities of success 14% - 97% Priority review voucher milestone $5.1 Probability-adjusted discounted cash flow Probability of success 16.4% Discount rate 15.7% The following table is a summary of the changes in the fair value of the Company's valuations for the deferred and contingent consideration liabilities for the three months ended March 31, 2024 and 2023 (in thousands): Deferred Contingent Consideration Balance as of December 31, 2022 $ 7,400 $ 58,100 Additions — — Change in Fair Value (1,200) (8,300) Payments — — Balance as of March 31, 2023 $ 6,200 $ 49,800 Balance as of December 31, 2023 $ 5,700 $ 84,600 Additions — — Change in Fair Value (700) (11,200) Payments — — Balance as of March 31, 2024 $ 5,000 $ 73,400 Convertible Notes The fair value of the convertible notes, which differs from their carrying value, is influenced by interest rates, the Company's stock price and stock price volatility (collectively, the Current Market Factors), and is determined by prices for the convertible notes observed in market trading which are Level 2 inputs. The estimated fair value of the Company's 0.75% convertible senior notes due 2028 (the 2028 Convertible Notes) (categorized as a Level 2 liability for fair value measurement purposes) as of March 31, 2024 was $620.1 million, deter mined using Current Market Factors and the ability of the Company to obtain debt on comparable terms to the 2028 Convertible Notes. The estimated fair value of the Company's 1.75% convertible senior notes due 2025 (the 2025 Convertible Notes) (categorized as a Level 2 liability for fair value measurement purposes) as of March 31, 2024 wa s $238.7 million, determined using Current Market Factors, and the ability of the Company to obtain debt on comparable terms to the 202 5 Convertible Notes. See Note 10 - Debt for further details on the Company's convertible notes. Synthetic Royalty Financing Agreement In October 2022, the Company entered into a revenue interest purchase agreement (the Royalty Financing Agreement) with OrbiMed Royalty & Credit Opportunities IV, LP (OrbiMed). Under the Royalty Financing Agreement, OrbiMed paid the Company $150 million in exchange for the right to receive, on a quarterly basis, royalties in an amount equal to 4% of ARIKAYCE global net sales prior to September 1, 2025 and 4.5% of ARIKAYCE global net sales on or after September 1, 2025, as well as 0.75% of brensocatib global net sales, if approved (the Revenue Interest Payments). In the event that OrbiMed has not received aggregate Revenue Interest Payments of at least $150 million on or prior to March 31, 2028, the Company must make a one-time payment to OrbiMed for the difference between the $150 million and the aggregated Revenue Interest Payments that have been paid. In addition, the royalty rate for ARIKAYCE will be increased beginning March 31, 2028 to the rate which would have resulted in aggregate Revenue Interest Payments as of March 31, 2028 equaling $150 million . The total Revenue Interest Payments payable by the Company to OrbiMed are capped at 1.8x of the purchase price or up to a maximum of 1.9x of the purchase price under certain conditions. The fair value of the Royalty Financing Agreement at the time of the transaction was based on the Company’s estimates of future royalties expected to be paid to OrbiMed over the life of the arrangement, which was determined using forecasts from market data sources, which are considered Level 3 inputs. This liability is being amortized using the effective interest method over the life of the arrangement, in accordance with ASC 470, Debt and ASC 835, Interest. The Company will utilize the prospective method to account for subsequent changes in the estimated future payments to be made to OrbiMed and will update the effective interest rate on a quarterly basis. For more information, see Note 11 - Royalty Financing Agreement .

Product Revenues, Net

Product Revenues, Net	3 Months Ended
Product Revenues, Net	Mar. 31, 2024
Revenue from Contract with Customer [Abstract]
Product Revenues, Net	4. 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 specialty distributors. 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 mentioned above. The following table presents a geographic summary of the Company's product revenues, net, for the three months ended March 31, 2024 and 2023 (in thousands): Three Months Ended March 31, 2024 2023 US $ 56,349 $ 49,067 Japan 14,891 13,156 Europe and rest of world 4,260 2,991 Total product revenues, net $ 75,500 $ 65,214 Revenue is recorded at net selling price (transaction price), which includes estimates of variable consideration for which reserves are established for (a) customer credits, such as invoice discounts for prompt pay, (b) estimated government rebates, such as Medicaid and Medicare Part D reimbursements, and estimated managed care rebates, (c) estimated chargebacks, and (d) estimated costs of co-payment assistance. These reserves are based on the amounts earned or to be claimed on the related sales and are classified as reductions of accounts receivable (prompt pay discounts and chargebacks), prepaid expenses (co-payment assistance), or as a current liability (rebates). Where appropriate, these estimates take into consideration a range of possible outcomes which are probability-weighted for relevant factors such as the Company's historical experience, current contractual and statutory requirements, and forecasted customer buying and payment patterns. Overall, these reserves reflect the Company's best estimates of the amount of consideration to which it is entitled based on the terms of the applicable contract. The amount of variable consideration included in the transaction price may be constrained and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. Actual amounts of consideration ultimately received may differ from the Company's estimates. If actual results in the future vary from estimates, the Company adjusts these estimates, which would affect net product revenue and earnings in the period such variances become known. Customer credits: Certain of the Company's customers are offered various forms of consideration, including prompt payment discounts. The payment terms for sales to specialty pharmacies and specialty distributors for prompt payment discounts are based on contractual rates agreed with the respective specialty pharmacies and distributors. The Company anticipates that its customers will earn these discounts and, therefore, deducts the full amount of these discounts from total gross product revenues at the time such revenues are recognized. Rebates: The Company contracts with certain government agencies and managed care organizations, or collectively, third-party payors, so that ARIKAYCE will be eligible for purchase by, or partial or full reimbursement from, such third-party payors. The Company estimates the rebates it will provide to third-party payors and deducts these estimated amounts from total gross product revenues at the time the revenues are recognized. These reserves are recorded in the same period in which the revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability. The current liability is included in accounts payable and accrued liabilities on the consolidated balance sheets. The Company estimates the rebates that it will provide to third-party payors based upon (i) the Company's contracts with these third-party payors, (ii) the government mandated discounts applicable to government-funded programs, (iii) a range of possible outcomes that are probability-weighted for the estimated payor mix, and (iv) information obtained from the Company's specialty pharmacies. Chargebacks: Chargebacks are discounts that occur when certain contracted customers, currently public health service institutions and federal government entities purchasing via the Federal Supply Schedule, purchase directly from the Company's specialty distributor. Contracted customers generally purchase the product at a discounted price and the specialty distributor, in turn, charges back to the Company the difference between the price the specialty distributor initially paid and the discounted price paid by the contracted customers. The Company estimates chargebacks provided to the specialty distributor and deducts these estimated amounts from gross product revenues, and from accounts receivable, at the time revenues are recognized. Co-payment assistance: Patients who have commercial insurance and meet certain eligibility requirements may receive co-payment assistance. Based upon the terms of the program and information regarding programs provided for similar specialty pharmaceutical products, the Company estimates the average co-pay mitigation amounts and the percentage of patients that it expects to participate in the program in order to establish accruals for co-payment assistance. These reserves are recorded in the same period in which the related revenue is recognized, resulting in a reduction of product revenue. The Company adjusts its accruals for co-pay assistance based on actual redemption activity and estimates of future redemptions related to sales in the current period. If any, or all, of the Company's actual experience varies from its estimates, the Company may need to adjust prior period accruals, affecting revenue in the period of adjustment.

Inventory

Inventory	3 Months Ended
Inventory	Mar. 31, 2024
Inventory Disclosure [Abstract]
Inventory	5. Inventory The Company's inventory balance consists of the following (in thousands): As of March 31, 2024 December 31, 2023 Raw materials $ 21,943 $ 24,562 Work-in-process 29,359 33,480 Finished goods 31,655 25,206 $ 82,957 $ 83,248 Inventory is stated at the lower of cost and net realizable value and consists of raw materials, work-in-process and finished goods. The Company has not recorded any significant inventory write-downs. The Company currently uses a limited number of third-party contract manufacturing organizations (CMOs) to produce its inventory.

Intangibles, Net and Goodwill

Intangibles, Net and Goodwill	3 Months Ended
Intangibles, Net and Goodwill	Mar. 31, 2024
Goodwill and Intangible Assets Disclosure [Abstract]
Intangibles, Net and Goodwill	6. Intangibles, Net and Goodwill Intangibles, Net Finite-lived Intangible Assets As of March 31, 2024, the Company's finite-lived intangible assets consisted of acquired ARIKAYCE R&D and the milestones paid to PARI for the license to use the Lamira® Nebulizer System (Lamira) for the delivery of ARIKAYCE to patients as a result of the US Food and Drug Administration (FDA) and EC approvals of ARIKAYCE in September 2018 and October 2020, respectively. The Company began amortizing its acquired ARIKAYCE R&D and PARI milestone-related intangible assets in October 2018, over ARIKAYCE's initial regulatory exclusivity period of 12 years. Amortization of these assets during each of the next five years is estimated to be approximately $5.1 million per year. Indefinite-lived Intangible Assets As of March 31, 2024, the Company's indefinite-lived intangible assets consisted of acquired IPR&D from the Business Acquisition (see Note 16 - Acquisitions ). Indefinite-lived intangible assets are not amortized. A rollforward of the Company's intangible assets for the three months ended March 31, 2024 and March 31, 2023 is as follows (in thousands): Intangible Asset December 31, 2023 Additions Amortization March 31, 2024 Acquired ARIKAYCE R&D $ 32,738 $ — $ (1,212) $ 31,526 Acquired IPR&D 29,600 — — 29,600 PARI milestones 1,366 — (51) 1,315 $ 63,704 $ — $ (1,263) $ 62,441 Intangible Asset December 31, 2022 Additions Amortization March 31, 2023 Acquired ARIKAYCE R&D $ 37,588 $ — $ (1,212) $ 36,376 Acquired IPR&D 29,600 — — 29,600 PARI milestones 1,568 — (51) 1,517 $ 68,756 $ — $ (1,263) $ 67,493 Goodwill The Company's goodwill balance of $136.1 million as of March 31, 2024 and December 31, 2023, resulted from the August 2021 Business Acquisition. See Note 16 - Acquisitions

Fixed Assets, Net

Fixed Assets, Net	3 Months Ended
Fixed Assets, Net	Mar. 31, 2024
Property, Plant and Equipment [Abstract]
Fixed Assets, Net	7. Fixed Assets, Net Fixed assets are stated at cost and depreciated using the straight-line method, based on useful lives as follows (in thousands): Estimated As of Asset Description March 31, 2024 December 31, 2023 Lab equipment 7 $ 23,468 $ 22,660 Furniture and fixtures 7 6,428 6,428 Computer hardware and software 3-5 6,106 6,001 Office equipment 7 89 89 Manufacturing equipment 7 1,336 1,336 Leasehold improvements 2-10 37,968 38,049 Construction in progress — 39,238 35,449 114,633 110,012 Less: accumulated depreciation (45,973) (44,628) $ 68,660 $ 65,384

Accounts Payable and Accrued Li

Accounts Payable and Accrued Liabilities	3 Months Ended
Accounts Payable and Accrued Liabilities	Mar. 31, 2024
Payables and Accruals [Abstract]
Accounts Payable and Accrued Liabilities	8. Accounts Payable and Accrued Liabilities Accounts payable and accrued liabilities consist of the following (in thousands): As of March 31, 2024 December 31, 2023 Accounts payable and other accrued operating expenses $ 44,018 $ 65,393 Accrued clinical trial expenses 23,754 23,711 Accrued professional fees 16,728 13,885 Accrued technical operation expenses 10,293 9,187 Accrued compensation and employee related costs 23,803 48,933 Accrued royalty and milestones payable 6,514 5,674 Accrued interest payable 2,269 2,175 Revenue Interest Payments payable 3,020 3,347 Accrued sales allowances and related costs 17,159 10,937 Accrued France ATU reimbursement payable 15,896 14,685 Deferred and contingent consideration 15,700 6,700 Other accrued liabilities 10,208 10,360 $ 189,362 $ 214,987

Leases

Leases	3 Months Ended
Leases	Mar. 31, 2024
Leases [Abstract]
Leases	9. Leases The Company's lease portfolio consists primarily of office and laboratory space, manufacturing facilities, research equipment and fleet vehicles. All of the Company's leases are classified as operating leases, except for the Company's leases of its corporate headquarters and a research facility in San Diego, which are classified as finance leases. The terms of the Company's lease agreements that have commenced range from less than one year to ten years, ten months. In its assessment of the term of each such lease, the Company has not included any options to extend or terminate the lease due to the absence of economic incentives in its lease agreements. Leases that qualify for treatment as a short-term lease are expensed as incurred. These short-term leases are not material to the Company's financial position. Furthermore, the Company does not separate lease and non-lease components for all classes of underlying assets. The Company's leases do not contain residual value guarantees and it does not sublease any of its leased assets. The Company outsources its manufacturing operations to CMOs. Upon review of the agreements with its CMOs, the Company determined that these contracts contain embedded leases for dedicated manufacturing facilities. The Company obtains substantially all of the economic benefits from the use of the manufacturing facilities, the Company has the right to direct how and for what purpose the facility is used throughout the period of use, and the supplier does not have the right to change the operating instructions of the facility. The operating lease right-of-use assets and corresponding lease liabilities associated with the manufacturing facilities is the sum of the minimum guarantees over the life of the production contracts. The Company also records variable consideration for variable lease payments in excess of fixed fees or minimum guarantees. Variable consideration related to the Company's leasing arrangements was $4.9 million and $0.1 million for the three months ended March 31, 2024 and 2023, respectively. Variable costs related to CMO manufacturing agreements are direct costs related to the manufacturing of ARIKAYCE and are capitalized within inventory in the Company's consolidated balance sheet, while the variable costs related to other leasing arrangements, not related to the manufacturing of ARIKAYCE, have been classified within operating expenses in the Company's consolidated statements of comprehensive loss. The table below summarizes the supplemental non-cash disclosures of the Company's leases included in its consolidated financial statements (in thousands): Three Months Ended March 31, 2024 2023 Finance right-of-use assets obtained in exchange for lease obligations $ — $ — Operating right-of-use assets obtained in exchange for lease obligations $ 5,656 $ 1,751 In addition to the Company's lease agreements that have previously commenced and are reflected in the consolidated financial statements, the Company has entered into additional lease agreements that have not yet commenced. The Company entered into certain agreements with Patheon UK Limited (Patheon) related to increasing its long-term production capacity for ARIKAYCE commercial inventory. The Company has determined that these agreements with Patheon contain an embedded lease for the manufacturing facility and the specialized equipment contained therein. Costs o f $52.0 million and $49.1 million incurred by the Company under these additional agreements have been classified within other assets in the Company's consolidated balance sheet as of March 31, 2024 and December 31, 2023, respectively. Upon the commencement date, prepaid costs and minimum guarantees specified in the agreement will be combined to establish an operating lease ROU asset and operating lease liability.
Leases	9. Leases The Company's lease portfolio consists primarily of office and laboratory space, manufacturing facilities, research equipment and fleet vehicles. All of the Company's leases are classified as operating leases, except for the Company's leases of its corporate headquarters and a research facility in San Diego, which are classified as finance leases. The terms of the Company's lease agreements that have commenced range from less than one year to ten years, ten months. In its assessment of the term of each such lease, the Company has not included any options to extend or terminate the lease due to the absence of economic incentives in its lease agreements. Leases that qualify for treatment as a short-term lease are expensed as incurred. These short-term leases are not material to the Company's financial position. Furthermore, the Company does not separate lease and non-lease components for all classes of underlying assets. The Company's leases do not contain residual value guarantees and it does not sublease any of its leased assets. The Company outsources its manufacturing operations to CMOs. Upon review of the agreements with its CMOs, the Company determined that these contracts contain embedded leases for dedicated manufacturing facilities. The Company obtains substantially all of the economic benefits from the use of the manufacturing facilities, the Company has the right to direct how and for what purpose the facility is used throughout the period of use, and the supplier does not have the right to change the operating instructions of the facility. The operating lease right-of-use assets and corresponding lease liabilities associated with the manufacturing facilities is the sum of the minimum guarantees over the life of the production contracts. The Company also records variable consideration for variable lease payments in excess of fixed fees or minimum guarantees. Variable consideration related to the Company's leasing arrangements was $4.9 million and $0.1 million for the three months ended March 31, 2024 and 2023, respectively. Variable costs related to CMO manufacturing agreements are direct costs related to the manufacturing of ARIKAYCE and are capitalized within inventory in the Company's consolidated balance sheet, while the variable costs related to other leasing arrangements, not related to the manufacturing of ARIKAYCE, have been classified within operating expenses in the Company's consolidated statements of comprehensive loss. The table below summarizes the supplemental non-cash disclosures of the Company's leases included in its consolidated financial statements (in thousands): Three Months Ended March 31, 2024 2023 Finance right-of-use assets obtained in exchange for lease obligations $ — $ — Operating right-of-use assets obtained in exchange for lease obligations $ 5,656 $ 1,751 In addition to the Company's lease agreements that have previously commenced and are reflected in the consolidated financial statements, the Company has entered into additional lease agreements that have not yet commenced. The Company entered into certain agreements with Patheon UK Limited (Patheon) related to increasing its long-term production capacity for ARIKAYCE commercial inventory. The Company has determined that these agreements with Patheon contain an embedded lease for the manufacturing facility and the specialized equipment contained therein. Costs o f $52.0 million and $49.1 million incurred by the Company under these additional agreements have been classified within other assets in the Company's consolidated balance sheet as of March 31, 2024 and December 31, 2023, respectively. Upon the commencement date, prepaid costs and minimum guarantees specified in the agreement will be combined to establish an operating lease ROU asset and operating lease liability.

Debt

Debt	3 Months Ended
Debt	Mar. 31, 2024
Debt Disclosure [Abstract]
Debt	10. Debt Current portion of long-term debt and debt, long-term consists of the following commitments as of March 31, 2024 and December 31, 2023 (in thousands): As of March 31, 2024 December 31, 2023 Convertible notes $ 789,731 $ 788,909 Term Loan 373,544 366,404 Less: current portion of convertible notes (224,194) — Debt, long-term $ 939,081 $ 1,155,313 Convertible Notes In May 2021, the Company completed an underwritten public offering of $575.0 million aggregate principal amount of the 2028 Convertible Notes, including the exercise in full of the underwriters' option to purchase an additional $75.0 million in aggregate principal amount of 2028 Convertible Notes. The Company's net proceeds from the offering, after deducting underwriting discounts and commissions and other offering expenses of $15.7 million, were approximately $559.3 million. The 2028 Convertible Notes bear interest payable semiannually in arrears on June 1 and December 1 of each year, beginning on December 1, 2021. The 2028 Convertible Notes mature on June 1, 2028, unless earlier converted, redeemed, or repurchased. In January 2018, the Company completed an underwritten public offering of $450.0 million aggregate principal amount of the 2025 Convertible Notes, including the exercise in full of the underwriters' option to purchase an additional $50.0 million in aggregate principal amount of 2025 Convertible Notes. The Company's net proceeds from the offering, after deducting underwriting discounts and commissions and other offering expenses of $14.2 million, were approximately $435.8 million. The 2025 Convertible Notes bear interest payable semiannually in arrears on January 15 and July 15 of each year, beginning on July 15, 2018. The 2025 Convertible Notes mature on January 15, 2025, unless earlier converted, redeemed, or repurchased. A portion of the net proceeds from the 2028 Convertible Notes was used to repurchase $225.0 million of the Company's outstanding 2025 Convertible Notes. The Company recorded a loss on early extinguishment of debt of $17.7 million, primarily related to the premium paid on extinguishment of a portion the 2025 Convertible Notes. On or after October 15, 2024, until the close of business on the second scheduled trading day immediately preceding January 15, 2025, holders may convert their 2025 Convertible Notes at any time. The initial conversion rate for the 2025 Convertible Notes is 25.5384 shares of common stock per $1,000 principal amount of 2025 Convertible Notes (equivalent to an initial conversion price of approximately $39.16 per share of common stock). On or after March 1, 2028, until the close of business on the second scheduled trading day immediately preceding June 1, 2028, holders may convert their 2028 Convertible Notes at any time. The initial conversion rate for the 2028 Convertible Notes is 30.7692 shares of common stock per $1,000 principal amount of 2028 Convertible Notes (equivalent to an initial conversion price of approximately $32.50 per share of common stock). Upon conversion of either the 2025 Convertible Notes or the 2028 Convertible Notes, holders may receive cash, shares of the Company's common stock or a combination of cash and shares of the Company's common stock, at the Company's option. The conversion rates will be subject to adjustment in some events but will not be adjusted for any accrued and unpaid interest. Holders may convert their 2025 Convertible Notes prior to October 15, 2024 or their 2028 Convertible Notes prior to March 1, 2028, only under the following circumstances, subject to the conditions set forth in the applicable indenture: (i) during the five business day period immediately after any five consecutive trading day period (the measurement period) in which the trading price per $1,000 principal amount of the applicable series of convertible notes, as determined following a request by a holder of such convertible notes, for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the common stock and the conversion rate on such trading day, (ii) the Company elects to distribute to all or substantially all holders of the common stock (a) any rights, options or warrants (other than in connection with a stockholder rights plan for so long as the rights issued under such plan have not detached from the associated shares of common stock) entitling them, for a period of not more than 45 days from the declaration date for such distribution, to subscribe for or purchase shares of common stock at a price per share that is less than the average of the last reported sale prices of the common stock for the 10 consecutive trading day period ending on, and including, the trading day immediately preceding the declaration date for such distribution, or (b) the Company's assets, debt securities or rights to purchase securities of the Company, which distribution has a per share value, as reasonably determined by the board of directors, exceeding 10% of the last reported sale price of the common stock on the trading day immediately preceding the declaration date for such distribution, (iii) if a transaction or event that constitutes a fundamental change or a make-whole fundamental change occurs, or if the Company is a party to (a) a consolidation, merger, combination, statutory or binding share exchange or similar transaction, pursuant to which the common stock would be converted into, or exchanged for, cash, securities or other property or assets, or (b) any sale, conveyance, lease or other transfer or similar transaction in one transaction or a series of transactions of all or substantially all of the consolidated assets of the Company and its subsidiaries, taken as a whole, all or any portion of the applicable series of convertible notes may be surrendered by a holder for conversion at any time from or after the date that is 30 scheduled trading days prior to the anticipated effective date of the transaction, (iv) if during any calendar quarter commencing after the calendar quarter ending on March 31, 2018 or June 30, 2021 for the 2025 Convertible Notes and the 2028 Convertible Notes, respectively (and only during such calendar quarter), the last reported sale price of the common stock for at least 20 trading days (whether or not consecutive) during the period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day, or (v) if the Company sends a notice of redemption, a holder may surrender all or any portion of its convertible notes to which the notice of redemption relates for conversion at any time on or after the date the applicable notice of redemption was sent until the close of business on (a) the second business day immediately preceding the related redemption date or (b) if the Company fails to pay the redemption price on the redemption date as specified in such notice of redemption, such later date on which the redemption price is paid. To date, there have not been any holder-initiated redemption requests of either series of convertible notes. Each series of convertible notes can be settled in cash, common stock, or a combination of cash and common stock at the Company's option, and thus, the Company determined the embedded conversion options in both series of convertible notes are not required to be separately accounted for as a derivative. However, since the convertible notes are within the scope of the accounting guidance for cash convertible instruments, the Company is required to separate each series of convertible notes into liability and equity components. The carrying amount of the liability component of each series of convertible notes as of the date of issuance was calculated by measuring the fair value of a similar liability that did not have an associated equity component. The fair value was based on data from readily available pricing sources which utilize market observable inputs and other characteristics for similar types of instruments. The carrying amount of the equity component representing the embedded conversion option for each series of convertible notes was determined by deducting the fair value of the liability component from the gross proceeds of the applicable convertible notes. The excess of the principal amount of the liability component over its carrying amount is amortized to interest expense over the expected life of a similar liability that does not have an associated equity component using the effective interest method. The equity component is not remeasured as long as it continues to meet the conditions for equity classification in the accounting guidance for contracts in an entity’s own equity. The fair value of the liability component of the 2025 Convertible Notes on the date of issuance was estimated at $309.1 million using an effective interest rate of 7.6% and, accordingly, the residual equity component on the date of issuance was $140.9 million. The fair value of the liability component of the 2028 Convertible Notes on the date of issuance was estimated at $371.6 million using an effective interest rate of 7.1% and, accordingly, the residual equity component on the date of issuance was $203.4 million. The respective discounts were amortized to interest expense over the term of the applicable series of convertible notes through December 31, 2022, prior to the adoption of ASU 2020-06. The 2025 Convertible Notes and 2028 Convertible Notes have remaining terms of approximately 0.78 years and 4.17 years, respectively. The $565.5 million carrying value of the 2028 Convertible Notes as of March 31, 2024 excludes $9.5 million of unamortized debt issuance costs. The $224.2 million carrying value of the 2025 Convertible Notes as of March 31, 2024 excludes $0.8 million of unamortized debt issuance costs. The 2028 Convertible Notes and 2025 Convertible Notes are long-term and current liabilities, respectively, as of March 31, 2024. The following table presents the carrying value of the Company's convertible notes balance (in thousands): As of March 31, 2024 December 31, 2023 Face value of outstanding convertible notes $ 800,000 800,000 Debt issuance costs (10,269) (11,091) Less: current convertible notes (224,194) — Total long-term convertible notes $ 565,537 $ 788,909 Secured Senior Term Loan In October 2022, the Company entered into a $350 million senior secured term loan agreement with Pharmakon Advisors LP (Pharmakon), manager of the BioPharma Credit funds (the Term Loan). The Term Loan matures on October 19, 2027 and bears interest at a rate based upon the secured overnight financing rate (SOFR), subject to a SOFR floor of 2.5%, in addition to a margin of 7.75% per annum. Up to 50% of the interest payable during the first 24 months from the closing of the Term Loan may be paid-in-kind at the Company's election. If elected, paid-in-kind interest will be capitalized and added to the principal amount of the Term Loan. The Term Loan, including the paid-in-kind interest, will be repaid in eight equal quarterly payments starting in the 13th quarter following the closing of the Term Loan (i.e., the quarter ending March 31, 2026), except that the repayment start date may be extended at the Company's option for an additional four quarters, so that repayments start in the 17th quarter following the closing of the Term Loan, subject to the achievement of specified ARIKAYCE data thresholds and certain other conditions. During the three months ended March 31, 2024, paid-in-kind interest capitalized was $6.2 million. Net proceeds from the Term Loan, after deducting the lenders' fees and deal expenses of $15.2 million, were $334.8 million. The following table presents the carrying value of the Company’s Term Loan balance as of March 31, 2024 (in thousands): As of March 31, 2024 December 31, 2023 Original Term Loan balance $ 350,000 $ 350,000 Paid-in-kind interest capitalized 33,779 27,537 Term Loan issuance costs, unamortized (10,235) (11,133) Term Loan $ 373,544 $ 366,404 As of March 31, 2024, future principal repayments of debt for each of the years through maturity were as follows (in thousands): Year Ending December 31: 2024 $ — 2025 225,000 2026 191,890 2027 191,889 2028 575,000 2029 and thereafter — $ 1,183,779 Interest Expense Interest expense related to debt and finance leases for the three months ended March 31, 2024 and 2023 is as follows (in thousands): Three Months Ended March 31, 2024 2023 Convertible debt contractual interest expense $ 2,063 $ 2,063 Term Loan contractual interest expense 12,483 10,911 Royalty Financing Agreement interest expense 4,822 4,764 Amortization of debt issuance costs 1,851 1,724 Swap interest income (754) (73) Total debt interest expense 20,465 19,389 Finance lease interest expense 577 614 Total interest expense $ 21,042 $ 20,003

Royalty Financing Agreement

Royalty Financing Agreement	3 Months Ended
Royalty Financing Agreement	Mar. 31, 2024
Debt Disclosure [Abstract]
Royalty Financing Agreement	11. Royalty Financing Agreement In October 2022, the Company entered into the Royalty Financing Agreement with OrbiMed. Under the Royalty Financing Agreement, OrbiMed paid the Company $150 million in exchange for the right to receive, on a quarterly basis, royalties in an amount equal to 4% of ARIKAYCE global net sales prior to September 1, 2025 and 4.5% of ARIKAYCE global net sales on or after September 1, 2025, as well as 0.75% of brensocatib global net sales, if approved. In the event that OrbiMed has not received aggregate Revenue Interest Payments of at least $150 million on or prior to March 31, 2028, the Company must make a one-time payment to OrbiMed for the difference between the $150 million and the aggregated Revenue Interest Payments that have been paid. In addition, the royalty rate for ARIKAYCE will be increased beginning March 31, 2028 to the rate which would have resulted in aggregate Revenue Interest Payments as of March 31, 2028 equaling $150 million. The total Revenue Interest Payments payable by the Company to OrbiMed are capped at 1.8x of the purchase price or up to a maximum of 1.9x of the purchase price under certain conditions. Net proceeds from the Royalty Financing Agreement, after deducting the lenders' fees and deal expenses of $3.8 million were, $146.2 million. The fair value of the Royalty Financing Agreement at the time of the transaction was based on the Company’s estimates of future royalties expected to be paid to OrbiMed over the life of the arrangement, which was determined using forecasts from market data sources, which are considered Level 3 inputs. This liability is being amortized using the effective interest method over the life of the arrangement, in accordance ASC 470, Debt and ASC 835, Interest. The initial annual effective interest rate was determined to be 12.4%. The Company is utilizing the prospective method to account for subsequent changes in the estimated future payments to be made to OrbiMed and updates the effective interest rate on a quarterly basis. The following table shows the activity within the liability account for the three-month period ended March 31, 2024 and year ended December 31, 2023 (in thousands): Three Months Ended Twelve Months Ended Royalty financing agreement liability - beginning balance $ 158,162 $ 151,538 Revenue Interest Payments paid and payable (3,020) (12,222) Interest expense recognized 4,822 18,846 Royalty financing agreement liability - ending balance $ 159,964 $ 158,162 Royalty financing issuance costs: Royalty issuance costs, unamortized - beginning balance $ (3,128) $ (3,523) Amortization of issuance costs 131 521 Other — (126) Deferred issuance costs, unamortized - ending balance $ (2,997) $ (3,128) Royalty Financing Agreement $ 156,967 $ 155,034 The Revenue Interest Payments payable in connection with the royalty financing agreement were $3.0 million and $3.3 million as of March 31, 2024 and December 31, 2023, respectively, which were recorded within accounts payable and accrued expenses on the consolidated balance sheet. Non-cash interest expense is recorded within interest expense in the consolidated statements of comprehensive loss.

Shareholders' Equity

Shareholders' Equity	3 Months Ended
Shareholders' Equity	Mar. 31, 2024
Equity [Abstract]
Shareholders' Equity	12. Shareholders' Equity Common Stock —As of March 31, 2024, the Company had 500,000,000 shares of common stock authorized with a par value of $0.01 per share and 148,560,882 shares of common stock issued and outstanding. In addition, as of March 31, 2024, the Company had reserved 24,098,410 shares of common stock for issuance upon the exercise of outstanding stock options, 3,058,943 shares of common stock for issuance upon the vesting of RSUs and 666,382 shares for issuance upon the vesting of PSUs. The Company has also reserved 23,438,430 shares of common stock in the aggregate for issuance upon conversion of the 2025 Convertible Notes and 2028 Convertible Notes, subject to adjustment in accordance with the applicable indentures. In connection with the Business Acquisition, the Company reser ved 9,406,112 s hares of the Company’s common stock, subject to certain closing-related reductions. The shares of the Company’s common stock reserved in connection with the Motus acquisition were partly issued as acquisition consideration at closing and on the first and second anniversaries of the closing date of the acquisition, and will also be issued upon the third anniversary of the closing date of the acquisition and upon the achievement of certain development and regulatory milestone events, subject to certain reductions. The shares of the Company’s common stock reserved in connection with the AlgaeneX acquisition will be issued upon the achievement of a development milestone event, subject to certain reductions. Of the 9,406,112 shares reserved, subject to certain closing-related reductions, the Company issued 2,889,367 shares of the Company's common stock in connection with the Business Acquisition (see Note 16 - Acquisitions ) in the third quarter of 2021, after certain closing-related deductions. In the third quarter of 2022, the Company issued 171,427 shares of the Company's common stock to fulfill the payment required to Motus equityholders on the first anniversary of the Business Acquisition. In the third quarter of 2023, the Company issued 177,203 shares of the Company's common stock to fulfill the payment required to Motus equityholders on the second anniversary of the Business Acquisition. In the second quarter of 2023, in connection with the Company's acquisition of Adrestia Therapeutics Ltd. (Adrestia), the Company issued 3,430,867 shares of the Company's common stock as consideration at closing. See Note 16 - Acquisitions for further details. In connection with the Company’s acquisition of Vertuis Bio, Inc. (Vertuis), the Company reserved 550,000 shares of the Company’s common stock, subject to future adjustment. An aggregate of 500,000 of the reserved shares were issued as acquisition consideration at closing. An additional $1 million of shares of common stock will be issued to Vertuis’ former stockholders on July 1, 2024, based on the share price on June 28, 2024. See Note 16 - Acquisitions for further details. In October 2022, the Company completed an underwritten offering of 13,750,000 shares of the Company's common stock at a public offering price of $20.00 per share. The Company's net proceeds from the sale of the shares, after deducting the underwriting discounts and offering expense of $16.2 million, were $258.8 million. In the first quarter of 2021, the Company entered into a sales agreement with SVB Leerink LLC (now known as Leerink Partners LLC) (Leerink), to sell shares of the Company's common stock, with aggregate gross sales proceeds of up to $250.0 million, from time to time, through an “at the market” equity offering program (the ATM program), under which Leerink acted as sales agent. In 2023, the Company issued and sold an aggregate of 6,503,041 shares of common stock through the ATM program at a weighted-average public offering price of $24.12 per share and received net proceeds of $152.2 million . In the first quarter of 2024, the Company entered into a new sales agreement with Leerink to sell shares of the Company's common stock, with aggregate gross sales proceeds of up to $500.0 million, from time to time, through a new “at the market” equity offering program (the new ATM program), under which Leerink acts as sales agent. In connection with entering into the new ATM program, the Company terminated the ATM program. The Company has not issued any shares under the new ATM program. Preferred Stock —As of March 31, 2024, the Company had 200,000,000 shares of preferred stock authorized with a par value of $0.01 per share and no shares of preferred stock were issued and outstanding.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
Stock-Based Compensation	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	13. Stock-Based Compensation The Company's current equity compensation plan, the Insmed Incorporated Amended and Restated 2019 Incentive Plan (the 2019 Incentive Plan), was approved by shareholders at the Company's Annual Meeting of Shareholders on May 11, 2023. The 2019 Incentive Plan replaced the Insmed Incorporated 2019 Incentive Plan. The 2019 Incentive Plan is administered by the Compensation Committee of the Board of Directors of the Company. Under the terms of the 2019 Incentive Plan, the Company is authorized to grant a variety of incentive awards based on its common stock, including stock options (both incentive stock options and non-qualified stock options), RSUs, performance options/shares and other stock awards to eligible employees and non-employee directors. The Company has submitted a proposal to its shareholders to approve an amendment to the 2019 Incentive Plan at the 2024 Annual Meeting of Shareholders (Amendment No.1). Amendment No.1, if approved, will provide for the issuance of an additional 3,000,000 shares under the 2019 Incentive Plan. As of March 31, 2024, 4,705,225 shares remain available for future issuance under the 2019 Incentive Plan. The 2019 Incentive Plan will terminate on May 16, 2029 unless it is extended or terminated earlier pursuant to its terms. In addition, from time to time, the Company makes inducement grants of stock options to new hires, which awards are made pursuant to the Nasdaq's inducement grant exception to the shareholder approval requirement for grants of equity compensation. During the three months ended March 31, 2024, the Company granted inducement stock options covering 358,140 shares of the Company's common stock to new employees. On May 15, 2018, the 2018 Employee Stock Purchase Plan (ESPP) was approved by shareholders at the Company's 2018 Annual Meeting of Shareholders. The Company has reserved the following for issuance under the ESPP: (i) 1,000,000 shares of common stock, plus (ii) commencing on January 1, 2019 and ending on December 31, 2023, an additional number of shares to be added on the first day of each calendar year equal to the lesser of (A) 1,200,000 shares of common stock, (B) 2% of the number of outstanding shares of common stock on such date and (C) an amount determined by the administrator. Stock Options —As of March 31, 2024, there was $148.0 million of unrecognized compensation expense related to unvested stock options. As of March 31, 2024, the Company had performance-conditioned options totaling 114,780 shares outstanding which had not yet met the recognition criteria. Restricted Stock Units —As of March 31, 2024, there was $55.8 million of unrecognized compensation expense related to unvested RSU awards. Performance Stock Units —As of March 31, 2024, there were 266,550 unvested PSUs outstanding with an unrecognized compensation expense of $10.4 million, which assumes a payout at 100% of the target. The following table summarizes the aggregate stock-based compensation expense recorded in the consolidated statements of comprehensive loss related to stock options, RSUs and the ESPP during the three months ended March 31, 2024 and 2023, respectively (in millions): Three Months Ended March 31, 2024 2023 Research and development $ 10.4 $ 7.9 Selling, general and administrative 11.1 8.5 Total $ 21.5 $ 16.4 There was no stock-based compensation expense recorded in the consolidated statements of comprehensive loss related to PSUs during the three months ended March 31, 2024 or March 31, 2023, as the performance conditions associated with the PSU awards were not probable as of either date.

Income Taxes

Income Taxes	3 Months Ended
Income Taxes	Mar. 31, 2024
Income Tax Disclosure [Abstract]
Income Taxes	14. Income Taxes The Company recorded a provision for income taxes of $0.6 million and $0.5 million for the three months ended March 31, 2024 and 2023, respectively. The provisions recorded for the three months ended March 31, 2024 and 2023 are primarily a result of certain of the Company's international subsidiaries, which had taxable income during the periods. Additionally, the Company is impacted by certain state taxes which effectively impose income tax on modified gross revenues. In jurisdictions where the Company has net losses, there was a full valuation allowance recorded against the Company's deferred tax assets and therefore no tax benefit was recorded. The Company is subject to US federal, state and international income taxes and the statute of limitations for tax audit is open for the Company’s federal tax returns for the years ended 2020 and later, generally open for certain states for the years 2019 and later, and generally open for international jurisdictions for the years 2018 and later. The Company has incurred net operating losses since inception, except for the year ended December 31, 2009. Such loss carryforwards would be subject to audit in any tax year in which those losses are utilized, notwithstanding the year of origin. As of March 31, 2024 and December 31, 2023, the Company had recorded reserves for unrecognized income tax benefits against certain deferred tax assets in the US. However, given the Company’s valuation allowance position, these reserves do not have an impact on the balance sheet as of March 31, 2024 and December 31, 2023 or the consolidated statements of comprehensive loss for the three months ended March 31, 2024 and 2023. The Company has not recorded any accrued interest or penalties related to uncertain tax positions. The Company does not anticipate any material changes in the amount of unrecognized tax positions over the next twelve months.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	15. Commitments and Contingencies Rent expense charged to operations was $3.1 million and $2.2 million for the three months ended March 31, 2024 and 2023, respectively. Legal Proceedings From time to time, the Company is a party to various lawsuits, claims and other legal proceedings that arise in the ordinary course of business. While the outcomes of these matters are uncertain, management does not expect that the ultimate costs to resolve these matters will have a material adverse effect on the Company's consolidated financial position, results of operations or cash flows.

Acquisitions

Acquisitions	3 Months Ended
Acquisitions	Mar. 31, 2024
Business Combination and Asset Acquisition [Abstract]
Acquisitions	16. Acquisitions Asset Acquisitions Adrestia Therapeutics Ltd. In June 2023, the Company acquired all of the issued and outstanding share capital of Adrestia, a privately held, preclinical stage company. At the closing of the transaction, the Company issued an aggregate of 3,430,867 shares of the Company’s common stock to Adrestia’s former shareholders (collectively, the Adrestia shareholders). The closing share price on the date of the transaction was $21.10, resulting in a purchase price of $72.4 million. The Adrestia shareholders may also become entitled to receive contingent payments up to an aggregate of $326.5 million in cash upon the achievement of certain development, regulatory and commercial milestone events, as well as royalty payments based upon a low single-digit percentage of net sales of certain products, both subject to the terms and conditions of the agreement. The shares of the Company’s common stock issued to the Adrestia shareholders were issued pursuant to Section 4(a)(2) of the Securities Act of 1933 (and, with respect to certain Adrestia shareholders, in reliance on Regulation S promulgated under the Securities Act of 1933). The Company did not receive any net proceeds from the issuance of common stock to the Adrestia shareholders. The Company evaluated the acquisition under ASC 805 and ASU 2017-01 and concluded that substantially all of the fair value of the gross assets acquired are concentrated in a single identifiable asset or a group of similar identifiable assets and accounted for the transaction as an asset acquisition. The Company determined that the IPR&D acquired did not have any future alternative use and, in accordance with ASC 730, Research and Development, expensed the assets within research and development in the consolidated statement of comprehensive loss as of the date of the acquisition. The Company recognized $76.5 million as IPR&D expense, after adjusting for working capital assumed in connection with the asset acquisition. Vertuis Bio, Inc. In January 2023, the Company acquired Vertuis, a privately held, preclinical stage company. At the closing of the transaction, the Company issued an aggregate of 500,000 shares of the Company’s common stock to Vertuis’ former stockholders and an individual who are entitled to receive a portion of the acquisition consideration (collectively, the Vertuis equityholders). The closing share price on the date of the transaction was $18.50. The Company is obligated to issue to Vertuis equityholders shares of the Company’s common stock on July 1, 2024 with an aggregate value of $1.0 million, based on the share price on June 28, 2024, and pay to the Vertuis equityholders up to an aggregate of $23.0 million in cash upon the achievement of certain development and regulatory milestone events, and up to an aggregate of $63.8 million in cash upon the achievement of certain net sales-based milestone events, in each case, subject to certain reductions. The shares of the Company’s common stock issued to the Vertuis equityholders were issued, and the shares issuable in the future will be issued, pursuant to Section 4(a)(2) of the Securities Act of 1933. The following table summarizes the purchase price (in millions). Shares of Insmed common stock issued on closing $ 9.25 Shares of Insmed common stock issuable on July 1, 2024 1.00 Total purchase price $ 10.25 The Company evaluated the acquisition under ASC 805 and ASU 2017-01 and concluded that substantially all of the fair value of the gross assets acquired are concentrated in a single identifiable asset or a group of similar identifiable assets and accounted for the transaction as an asset acquisition. The Company determined that the assets acquired did not have any future alternative use and, in accordance with ASC 730, Research and Development, expensed the assets within research and development in the consolidated statement of comprehensive loss as of the date of the acquisition. Business Combination On August 4, 2021, the Company acquired all of the equity interests of Motus and AlgaeneX, each a privately held, preclinical stage company. In connection with the closing of the Company’s acquisition of Motus, the Company issued an aggregate of 2,889,367 shares of the Company’s common stock, following certain closing-related reductions, to Motus’s former stockholders and option holders and certain individuals who are entitled to receive a portion of the acquisition consideration (collectively, Motus equityholders), subject to certain adjustments . The Company is 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 and up to 5,348,572 shares in the aggregate upon the achievement of certain development and regulatory milestone events, and to pay to the Motus equityholders an aggregate of $35 million upon the achievement of certain net sales-based milestones and a portion of the value of a priority review voucher (to the extent issued to the Company), in each case, subject to certain reductions. During August 2022 and August 2023, the Company fulfilled the payments due on the first and second anniversaries of the closing date by issuing 171,427 shares and 177,203 shares of the Company's common stock, respectively, after certain reductions. At the closing of the Company’s acquisition of AlgaeneX, the Company paid $1.5 million in cash to AlgaeneX’s former stockholders and certain individuals who are entitled to receive a portion of the acquisition consideration (collectively, the AlgaeneX equityholders). The Company is obligated to issue to the AlgaeneX equityholders an aggregate of 368,867 shares of the Company’s common stock upon the achievement of a development milestone event and pay to the AlgaeneX equityholders a mid-single digits licensing fee on certain future payments received by the Company in licensing transactions for AlgaeneX’s manufacturing technology, in each case, subject to certain reductions. The shares of the Company’s common stock issued to the Motus equityholders and the AlgaeneX equityholders were issued, and the shares issuable in the future will be issued, pursuant to Section 4(a)(2) of the Securities Act of 1933, and the numbers of such issued and issuable shares was calculated based on a per share value of $27.11, which was the weighted average price per share of the Company's common stock preceding the closing of the Business Acquisition for the 45 consecutive trading day period beginning on May 24, 2021. The Company will not receive any proceeds from the issuance of common stock to the Motus equityholders or the AlgaeneX equityholders. The Company evaluated the Business Acquisition under ASC 805 and ASU 2017-01. The Company concluded that substantially all of the fair value of the gross assets acquired is not concentrated in a single identifiable asset or a group of similar identifiable assets. The transaction does not pass the screen test and thus management performed a full assessment to determine if the acquired entities met the definition of a business. For the full assessment, management considered whether it has acquired (a) inputs, (b) substantive processes, and (c) outputs. Under ASC 805, to be considered a business, a set of activities and assets is required to have only the first two of the three elements, which together are or will be used in the future to create outputs. Management determined that the acquired entities met the definition of a business since the Company acquired inputs and substantive processes capable of producing outputs. Therefore, the transaction has been accounted for under the acquisition method of accounting. Under the acquisition method, the total purchase price of the acquisition is allocated to the net tangible and identifiable intangible assets acquired and liabilities assumed based on the fair values as of the date of the acquisition. The fair value of the consideration totaled approximately $165.5 million. The results of Motus's and AlgaeneX's operations have been included in the Company's consolidated statements of comprehensive loss beginning on the acquisition date. The fair value of IPR&D was capitalized as of the acquisition date and accounted for as indefinite-lived intangible assets until completion or disposition of the assets or abandonment of the associated research and development efforts. Upon successful completion of the development efforts, the useful lives of the IPR&D assets will be determined based on the anticipated period of regulatory exclusivity and will be amortized within operating expenses. Until that time, the IPR&D assets will be subject to impairment testing and will not be amortized. The goodwill recorded related to the acquisition is the excess of the fair value of the consideration transferred by the acquirer over the fair value of the net identifiable assets acquired and liabilities assumed at the date of acquisition. The goodwill recorded is not deductible for tax purposes.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net loss	$ (157,091)	$ (159,764)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Mar. 31, 2024 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	Our policy governing transactions in our securities by our directors, officers and employees permits our directors, officers and employees to enter into trading plans complying with Rule 10b5-1 under the Exchange Act. The following table describes the written plans for the sale of our securities adopted, modified or terminated by our executive officers and directors during the first quarter of 2024, each of which was entered into during an open trading window and is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) (each, a “Trading Plan”). Name and Title Date of Adoption of Trading Plan Scheduled Start Date of Trading Plan Scheduled Expiration Date of Trading Plan (1) Maximum Shares Subject to Trading Plan Date Plan Terminated William Lewis Chief Executive Officer 3/13/2023 10/27/2023 05/31/2024 105,000 2/26/2024 Sara Bonstein Chief Financial Officer 2/27/2024 5/28/2024 11/12/2024 241,288 N/A Drayton Wise Chief Commercial Officer 2/27/2024 6/03/2024 10/27/2025 37,000 N/A S. Nicole Schaeffer Chief People Strategy Officer 2/27/2024 6/03/2024 5/21/2025 63,734 N/A (1) A Trading Plan may expire on an earlier date if all contemplated transactions are completed before such Trading Plan’s expiration date, upon termination by broker or the holder of the Trading Plan, or as otherwise provided in the Trading Plan.
Non-Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Terminated	false
William Lewis [Member]
Trading Arrangements, by Individual
Name	William Lewis
Title	Chief Executive Officer
Adoption Date	3/13/2023
Rule 10b5-1 Arrangement Terminated	true
Termination Date	2/26/2024
Arrangement Duration	122 days
Aggregate Available	105,000
Sara Bonstein [Member]
Trading Arrangements, by Individual
Name	Sara Bonstein
Title	Chief Financial Office
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	2/27/2024
Arrangement Duration	168 days
Aggregate Available	241,288
Drayton Wise [Member]
Trading Arrangements, by Individual
Name	Drayton Wise
Title	Chief Commercial Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	2/27/2024
Arrangement Duration	511 days
Aggregate Available	37,000
S. Nicole Schaeffer [Member]
Trading Arrangements, by Individual
Name	S. Nicole Schaeffer
Title	Chief People Strategy Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	2/27/2024
Arrangement Duration	352 days
Aggregate Available	63,734

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2024
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, and accounting for research and development 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. The Company places its cash equivalents 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.
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.
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 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 March 31, 2024. Upon recognition of a contingent consideration payment, the amount is included in the cost of the acquired asset or group of assets.
Goodwill	Goodwill
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.
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' deficit, as a component of accumulated other comprehensive 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 expense, net.
Derivatives	Derivatives —In the normal course of business, the Company is exposed to the effects of interest rate changes. The Company may enter into derivative instruments, including interest rate swaps and caps, to manage or hedge interest rate risk. Derivative instruments are recorded at fair value on the balance sheet date. The Company has not elected hedge accounting treatment for the changes in the fair value of derivatives. Changes in the fair value of derivatives are recorded each period and are included in change in fair value of interest rate swap in the consolidated statements of comprehensive loss and consolidated statements of cash flows.
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.
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 (RS), 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.
Recently Adopted Accounting Pronouncements	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. ASU 2023-09 will be effective for fiscal years beginning after December 15, 2024. The Company is currently evaluating the impact of adoption of ASU 2023-09 on its consolidated financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
Summary of Significant Accounting Policies (Tables)	Mar. 31, 2024
Accounting Policies [Abstract]
Schedule of Percentage of Total Gross Product Revenue Represented by the Three Largest Customers	The following table presents the percentage of gross product revenue represented by the Company's three largest customers as of the three months ended March 31, 2024 and their respective percentages for the three months ended March 31, 2023. Three Months Ended March 31, 2024 2023 Customer A 35% 36% Customer B 34% 36% Customer C 16% 17%
Schedule of Reconciliation of the Weighted Average Number of Shares Used to Compute Basic and Diluted Net Loss per Share	The following table sets forth the reconciliation of the weighted average number of common shares used to compute basic and diluted net loss per share for the three months ended March 31, 2024 and 2023: Three Months Ended March 31, 2024 2023 Numerator: Net loss $ (157,091) $ (159,764) Denominator: Weighted average common shares used in calculation of basic net loss per share: 148,456 136,355 Effect of dilutive securities: Common stock options — — RS and RSUs — — PSUs — — Convertible debt securities — — Weighted average common shares outstanding used in calculation of diluted net loss per share 148,456 136,355 Net loss per share: Basic and diluted $ (1.06) $ (1.17)
Schedule of Potentially Dilutive Securities Excluded from Computations of Diluted Weighted Average Common Shares Outstanding	The following potentially dilutive securities have been excluded from the computations of diluted weighted average common shares outstanding as of March 31, 2024 and 2023, respectively, as their effect would have been anti-dilutive (in thousands): As of March 31, 2024 2023 Common stock options 24,098 19,156 Unvested RS and RSUs 3,059 2,058 PSUs 666 671 Convertible debt securities 23,438 23,438

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
Fair Value Measurements (Tables)	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Schedule of Carrying Value and Fair Value of Assets and Liabilities	The following table shows assets and liabilities that are measured at fair value on a recurring basis and their carrying value (in millions): As of March 31, 2024 Fair Value Carrying Value Level 1 Level 2 Level 3 Assets Cash and cash equivalents $ 595.7 $ 595.7 $ — $ — Collateral for interest rate swap $ 6.0 $ 6.0 $ — $ — Liabilities Interest rate swap $ (1.2) $ — $ (1.2) $ — Deferred consideration $ 5.0 $ — $ 5.0 $ — Contingent consideration $ 73.4 $ — $ — $ 73.4 As of December 31, 2023 Fair Value Carrying Value Level 1 Level 2 Level 3 Assets Cash and cash equivalents $ 482.4 $ 482.4 $ — $ — Marketable securities $ 298.1 $ 298.1 $ — $ — Collateral for interest rate swap $ 6.0 $ 6.0 $ — $ — Liabilities Interest rate swap $ 1.2 $ — $ 1.2 $ — Deferred consideration $ 5.7 $ — $ 5.7 $ — Contingent consideration $ 84.6 $ — $ — $ 84.6
Schedule of Observable Inputs in Valuation of Deferred Consideration	The following observable input was used in the valuation of the deferred consideration as of March 31, 2024: Fair Value as of March 31, 2024 (in millions) Observable Input Input Value Deferred consideration $5.0 Insmed share price as of March 31, 2024 $27.13 Fair Value as of March 31, 2024 (in millions) Valuation Technique Unobservable Inputs Values Development and regulatory milestones $65.5 Probability-adjusted Probabilities of success 14% - 97% Priority review voucher milestone $5.1 Probability-adjusted discounted cash flow Probability of success 16.4% Discount rate 15.7% The following table is a summary of the changes in the fair value of the Company's valuations for the deferred and contingent consideration liabilities for the three months ended March 31, 2024 and 2023 (in thousands): Deferred Contingent Consideration Balance as of December 31, 2022 $ 7,400 $ 58,100 Additions — — Change in Fair Value (1,200) (8,300) Payments — — Balance as of March 31, 2023 $ 6,200 $ 49,800 Balance as of December 31, 2023 $ 5,700 $ 84,600 Additions — — Change in Fair Value (700) (11,200) Payments — — Balance as of March 31, 2024 $ 5,000 $ 73,400

Product Revenues, Net (Tables)

Product Revenues, Net (Tables)	3 Months Ended
Product Revenues, Net (Tables)	Mar. 31, 2024
Revenue from Contract with Customer [Abstract]
Schedule of Product Revenues By Geographic Location	The following table presents a geographic summary of the Company's product revenues, net, for the three months ended March 31, 2024 and 2023 (in thousands): Three Months Ended March 31, 2024 2023 US $ 56,349 $ 49,067 Japan 14,891 13,156 Europe and rest of world 4,260 2,991 Total product revenues, net $ 75,500 $ 65,214

Inventory (Tables)

Inventory (Tables)	3 Months Ended
Inventory (Tables)	Mar. 31, 2024
Inventory Disclosure [Abstract]
Schedule of Inventory	The Company's inventory balance consists of the following (in thousands): As of March 31, 2024 December 31, 2023 Raw materials $ 21,943 $ 24,562 Work-in-process 29,359 33,480 Finished goods 31,655 25,206 $ 82,957 $ 83,248

Intangibles, Net and Goodwill (

Intangibles, Net and Goodwill (Tables)	3 Months Ended
Intangibles, Net and Goodwill (Tables)	Mar. 31, 2024
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Rollforward of Intangible Assets	A rollforward of the Company's intangible assets for the three months ended March 31, 2024 and March 31, 2023 is as follows (in thousands): Intangible Asset December 31, 2023 Additions Amortization March 31, 2024 Acquired ARIKAYCE R&D $ 32,738 $ — $ (1,212) $ 31,526 Acquired IPR&D 29,600 — — 29,600 PARI milestones 1,366 — (51) 1,315 $ 63,704 $ — $ (1,263) $ 62,441 Intangible Asset December 31, 2022 Additions Amortization March 31, 2023 Acquired ARIKAYCE R&D $ 37,588 $ — $ (1,212) $ 36,376 Acquired IPR&D 29,600 — — 29,600 PARI milestones 1,568 — (51) 1,517 $ 68,756 $ — $ (1,263) $ 67,493

Fixed Assets, Net (Tables)

Fixed Assets, Net (Tables)	3 Months Ended
Fixed Assets, Net (Tables)	Mar. 31, 2024
Property, Plant and Equipment [Abstract]
Schedule of Fixed Assets	Fixed assets are stated at cost and depreciated using the straight-line method, based on useful lives as follows (in thousands): Estimated As of Asset Description March 31, 2024 December 31, 2023 Lab equipment 7 $ 23,468 $ 22,660 Furniture and fixtures 7 6,428 6,428 Computer hardware and software 3-5 6,106 6,001 Office equipment 7 89 89 Manufacturing equipment 7 1,336 1,336 Leasehold improvements 2-10 37,968 38,049 Construction in progress — 39,238 35,449 114,633 110,012 Less: accumulated depreciation (45,973) (44,628) $ 68,660 $ 65,384

Accounts Payable and Accrued _2

Accounts Payable and Accrued Liabilities (Tables)	3 Months Ended
Accounts Payable and Accrued Liabilities (Tables)	Mar. 31, 2024
Payables and Accruals [Abstract]
Schedule of Accounts Payable and Accrued Liabilities	Accounts payable and accrued liabilities consist of the following (in thousands): As of March 31, 2024 December 31, 2023 Accounts payable and other accrued operating expenses $ 44,018 $ 65,393 Accrued clinical trial expenses 23,754 23,711 Accrued professional fees 16,728 13,885 Accrued technical operation expenses 10,293 9,187 Accrued compensation and employee related costs 23,803 48,933 Accrued royalty and milestones payable 6,514 5,674 Accrued interest payable 2,269 2,175 Revenue Interest Payments payable 3,020 3,347 Accrued sales allowances and related costs 17,159 10,937 Accrued France ATU reimbursement payable 15,896 14,685 Deferred and contingent consideration 15,700 6,700 Other accrued liabilities 10,208 10,360 $ 189,362 $ 214,987

Leases (Tables)

Leases (Tables)	3 Months Ended
Leases (Tables)	Mar. 31, 2024
Leases [Abstract]
Schedule of Supplemental Noncash Disclosures included in Consolidated Financial Statements	The table below summarizes the supplemental non-cash disclosures of the Company's leases included in its consolidated financial statements (in thousands): Three Months Ended March 31, 2024 2023 Finance right-of-use assets obtained in exchange for lease obligations $ — $ — Operating right-of-use assets obtained in exchange for lease obligations $ 5,656 $ 1,751

Debt (Tables)

Debt (Tables)	3 Months Ended
Debt (Tables)	Mar. 31, 2024
Debt Disclosure [Abstract]
Schedule of Debt, Current and Long-Term Portion of Debt	urrent portion of long-term debt and debt, long-term consists of the following commitments as of March 31, 2024 and December 31, 2023 (in thousands): As of March 31, 2024 December 31, 2023 Convertible notes $ 789,731 $ 788,909 Term Loan 373,544 366,404 Less: current portion of convertible notes (224,194) — Debt, long-term $ 939,081 $ 1,155,313
Schedule of Components of Debt Balance	The following table presents the carrying value of the Company's convertible notes balance (in thousands): As of March 31, 2024 December 31, 2023 Face value of outstanding convertible notes $ 800,000 800,000 Debt issuance costs (10,269) (11,091) Less: current convertible notes (224,194) — Total long-term convertible notes $ 565,537 $ 788,909 The following table shows the activity within the liability account for the three-month period ended March 31, 2024 and year ended December 31, 2023 (in thousands): Three Months Ended Twelve Months Ended Royalty financing agreement liability - beginning balance $ 158,162 $ 151,538 Revenue Interest Payments paid and payable (3,020) (12,222) Interest expense recognized 4,822 18,846 Royalty financing agreement liability - ending balance $ 159,964 $ 158,162 Royalty financing issuance costs: Royalty issuance costs, unamortized - beginning balance $ (3,128) $ (3,523) Amortization of issuance costs 131 521 Other — (126) Deferred issuance costs, unamortized - ending balance $ (2,997) $ (3,128) Royalty Financing Agreement $ 156,967 $ 155,034
Schedule of Carrying Value of Term Loan Balance	The following table presents the carrying value of the Company’s Term Loan balance as of March 31, 2024 (in thousands): As of March 31, 2024 December 31, 2023 Original Term Loan balance $ 350,000 $ 350,000 Paid-in-kind interest capitalized 33,779 27,537 Term Loan issuance costs, unamortized (10,235) (11,133) Term Loan $ 373,544 $ 366,404
Schedule of Future Principal Repayments of Debt	As of March 31, 2024, future principal repayments of debt for each of the years through maturity were as follows (in thousands): Year Ending December 31: 2024 $ — 2025 225,000 2026 191,890 2027 191,889 2028 575,000 2029 and thereafter — $ 1,183,779
Schedule of Interest Expense	Interest expense related to debt and finance leases for the three months ended March 31, 2024 and 2023 is as follows (in thousands): Three Months Ended March 31, 2024 2023 Convertible debt contractual interest expense $ 2,063 $ 2,063 Term Loan contractual interest expense 12,483 10,911 Royalty Financing Agreement interest expense 4,822 4,764 Amortization of debt issuance costs 1,851 1,724 Swap interest income (754) (73) Total debt interest expense 20,465 19,389 Finance lease interest expense 577 614 Total interest expense $ 21,042 $ 20,003

Royalty Financing Agreement (Ta

Royalty Financing Agreement (Tables)	3 Months Ended
Royalty Financing Agreement (Tables)	Mar. 31, 2024
Debt Disclosure [Abstract]
Schedule of Carrying Value of Royalty Financing Agreement	The following table presents the carrying value of the Company's convertible notes balance (in thousands): As of March 31, 2024 December 31, 2023 Face value of outstanding convertible notes $ 800,000 800,000 Debt issuance costs (10,269) (11,091) Less: current convertible notes (224,194) — Total long-term convertible notes $ 565,537 $ 788,909 The following table shows the activity within the liability account for the three-month period ended March 31, 2024 and year ended December 31, 2023 (in thousands): Three Months Ended Twelve Months Ended Royalty financing agreement liability - beginning balance $ 158,162 $ 151,538 Revenue Interest Payments paid and payable (3,020) (12,222) Interest expense recognized 4,822 18,846 Royalty financing agreement liability - ending balance $ 159,964 $ 158,162 Royalty financing issuance costs: Royalty issuance costs, unamortized - beginning balance $ (3,128) $ (3,523) Amortization of issuance costs 131 521 Other — (126) Deferred issuance costs, unamortized - ending balance $ (2,997) $ (3,128) Royalty Financing Agreement $ 156,967 $ 155,034

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
Stock-Based Compensation (Tables)	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Schedule of Allocation of Employee Stock-Based Compensation	The following table summarizes the aggregate stock-based compensation expense recorded in the consolidated statements of comprehensive loss related to stock options, RSUs and the ESPP during the three months ended March 31, 2024 and 2023, respectively (in millions): Three Months Ended March 31, 2024 2023 Research and development $ 10.4 $ 7.9 Selling, general and administrative 11.1 8.5 Total $ 21.5 $ 16.4

Acquisitions (Tables)

Acquisitions (Tables)	3 Months Ended
Acquisitions (Tables)	Mar. 31, 2024
Business Combination and Asset Acquisition [Abstract]
Schedule of Asset Acquisition	The following table summarizes the purchase price (in millions). Shares of Insmed common stock issued on closing $ 9.25 Shares of Insmed common stock issuable on July 1, 2024 1.00 Total purchase price $ 10.25

The Company and Basis of Pres_2

The Company and Basis of Presentation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 595,729		$ 482,374
Net loss	$ (157,091)	$ (159,764)

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details) - reportingUnit	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Number of reporting units	1	1

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Concentration Risk (Details) - Sales Revenue, Product Line - Customer Concentration Risk	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Customer A
Concentration Risk [Line Items]
Concentration risk, percentage	35%	36%
Customer B
Concentration Risk [Line Items]
Concentration risk, percentage	34%	36%
Customer C
Concentration Risk [Line Items]
Concentration risk, percentage	16%	17%

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Numerator:
Net loss	$ (157,091)	$ (159,764)
Denominator:
Weighted average common shares used in calculation of basic net loss per share (in shares)	148,456	136,355
Weighted average common shares used in calculation of basic net loss per share:
Convertible debt securities (in shares)	0	0
Weighted average common shares outstanding used in calculation of diluted net loss per share (in shares)	148,456	136,355
Net loss per share:
Basic (in dollars per share)	$ (1.06)	$ (1.17)
Diluted (in dollars per share)	$ (1.06)	$ (1.17)
Common stock options
Weighted average common shares used in calculation of basic net loss per share:
Effect of dilutive securities (in shares)	0	0
RS and RSUs
Weighted average common shares used in calculation of basic net loss per share:
Effect of dilutive securities (in shares)	0	0
PSUs
Weighted average common shares used in calculation of basic net loss per share:
Effect of dilutive securities (in shares)	0	0

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Anti-dilutive Securities (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Common stock options
Anti-dilutive securities excluded from computations of diluted weighted-average common shares outstanding
Potentially dilutive securities excluded from computations of diluted weighted-average shares outstanding (in shares)	24,098	19,156
Unvested RS and RSUs
Anti-dilutive securities excluded from computations of diluted weighted-average common shares outstanding
Potentially dilutive securities excluded from computations of diluted weighted-average shares outstanding (in shares)	3,059	2,058
PSUs
Anti-dilutive securities excluded from computations of diluted weighted-average common shares outstanding
Potentially dilutive securities excluded from computations of diluted weighted-average shares outstanding (in shares)	666	671
Convertible debt securities
Anti-dilutive securities excluded from computations of diluted weighted-average common shares outstanding
Potentially dilutive securities excluded from computations of diluted weighted-average shares outstanding (in shares)	23,438	23,438

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Carrying Value and Fair Value of Assets and Liabilities (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Liabilities
Deferred consideration	$ 5,000,000
Level 2
Liabilities
Contingent consideration	5,000,000	$ 5,700,000	$ 6,200,000	$ 7,400,000
Level 3
Liabilities
Contingent consideration	73,400,000	84,600,000	$ 49,800,000	$ 58,100,000
Carrying Value \| Recurring basis
Assets
Cash and cash equivalents	595,700,000	482,400,000
Marketable securities	0	298,100,000
Collateral for interest rate swap	6,000,000	6,000,000
Liabilities
Interest rate swap	(1,200,000)
Interest rate swap		1,200,000
Deferred consideration	5,000,000	5,700,000
Contingent consideration	73,400,000	84,600,000
Estimate of Fair Value Measurement \| Recurring basis \| Level 1
Assets
Cash and cash equivalents	595,700,000	482,400,000
Marketable securities		298,100,000
Collateral for interest rate swap	6,000,000	6,000,000
Liabilities
Interest rate swap	0
Interest rate swap		0
Deferred consideration	0	0
Contingent consideration	0	0
Estimate of Fair Value Measurement \| Recurring basis \| Level 2
Assets
Cash and cash equivalents	0	0
Marketable securities		0
Collateral for interest rate swap	0	0
Liabilities
Interest rate swap	(1,200,000)
Interest rate swap		1,200,000
Deferred consideration	5,000,000	5,700,000
Contingent consideration	0	0
Estimate of Fair Value Measurement \| Recurring basis \| Level 3
Assets
Cash and cash equivalents	0	0
Marketable securities		0
Collateral for interest rate swap	0	0
Liabilities
Interest rate swap	0
Interest rate swap		0
Deferred consideration	0	0
Contingent consideration	$ 73,400,000	$ 84,600,000

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) $ in Thousands

1 Months Ended

3 Months Ended

Aug. 04, 2021 USD ($) shares

Aug. 31, 2023 shares

Oct. 31, 2022 USD ($)

Aug. 31, 2022 shares

Aug. 31, 2021 sale shares

Mar. 31, 2024 USD ($)

Sep. 30, 2023 shares

Sep. 30, 2022 shares

Sep. 30, 2021 shares

Sep. 01, 2025

Dec. 31, 2023 USD ($)

Mar. 31, 2023 USD ($)

Dec. 31, 2022 USD ($)

Oct. 01, 2022

May 31, 2021 USD ($)

Jan. 31, 2018 USD ($)

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Payments to acquire marketable securities

$ 300,000

Deferred consideration

5,000

Non-current contingent consideration

63,700

$ 84,600

Development and regulatory milestones

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Contingent consideration

$ 65,500

Convertible notes

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Convertible senior notes

$ 309,100

0.75% convertible senior notes due 2028 | Convertible notes

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Interest rate (as a percent)

0.75%

Convertible senior notes

$ 371,600

Original Term Loan balance

575,000

1.75% convertible senior notes due 2025 | Convertible notes

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Interest rate (as a percent)

1.75%

Convertible senior notes

$ 238,700

$ 203,400

Original Term Loan balance

$ 450,000

Royalty Agreements | ARIKAYCE Global Net Sales

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Royalty percentage

Royalty Agreements | Brensocatib Global Net Sales

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Royalty percentage

75%

Royalty Agreements | Forecast | ARIKAYCE Global Net Sales

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Royalty percentage

4.50%

Royalty Agreements | Secured Debt

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Proceeds from royalty financing

$ 150,000

Original Term Loan balance

150,000

Interest payments

$ 150,000

Probabilities of success

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Weighted average probability of success

0.42

Level 3

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Contingent consideration

$ 73,400

84,600

$ 49,800

$ 58,100

Level 2

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Contingent consideration

5,000

5,700

$ 6,200

$ 7,400

Recurring basis | Level 3 | Estimate of Fair Value Measurement

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Marketable securities

Deferred consideration

Contingent consideration

73,400

84,600

Recurring basis | Level 2 | Estimate of Fair Value Measurement

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Marketable securities

Deferred consideration

5,000

5,700

Contingent consideration

$ 0

Recurring basis | Level 2 | 0.75% convertible senior notes due 2028 | Estimate of Fair Value Measurement

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Convertible senior notes

620,100

Accrued Liabilities, Current

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Deferred consideration

5,000

Motus

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Shares issued in acquisition (in shares) | shares

2,889,367

177,203

171,427

177,203

171,427

2,889,367

Shares issued upon milestone achievements (in shares) | shares

5,348,572

Contingent consideration

$ 35,000

Motus | Development and regulatory milestones

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Proceeds of sale of priority review voucher obligated to pay to equity holders, percentage

50%

Average sales prices of publicly disclosed priority review voucher sales obligated to pay equity holders, percentage

50%

Number of publicly disclosed sales used to determine average sales price owed to equity holders | sale

Motus | Second anniversary of closing date

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Shares issued in acquisition (in shares) | shares

184,433

Motus | First anniversary of closing date

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Shares issued in acquisition (in shares) | shares

184,433

Motus | Third anniversary of closing date

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Shares issued in acquisition (in shares) | shares

184,433

Motus | Level 3

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Current contingent consideration

9,700

Motus | Other Noncurrent Liabilities | Level 3

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Non-current contingent consideration

$ 63,700

AlgaeneX

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Shares issued upon milestone achievements (in shares) | shares

368,867

Fair Value Measurements - Obser

Fair Value Measurements - Observable Input in Valuation of Deferred Consideration (Details) $ in Millions	Mar. 31, 2024 USD ($) $ / shares
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred consideration \| $	$ 5
Level 2 \| Share Price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Insmed share price (in usd per share) \| $ / shares	27.13

Fair Value Measurements - Signi

Fair Value Measurements - Significant Unobservable Inputs in the Valuation of Contingent Consideration Liabilities (Details) $ in Thousands	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	$ 73,400	$ 84,600	$ 49,800	$ 58,100
Probabilities of success
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Values	0.42
Development and regulatory milestones
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	$ 65,500
Priority review voucher milestone
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	$ 5,100
Priority review voucher milestone \| Probabilities of success \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Values	0.164
Priority review voucher milestone \| Discount rate \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Values	0.157
Minimum \| Development and regulatory milestones \| Probabilities of success \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Values	0.14
Maximum \| Development and regulatory milestones \| Probabilities of success \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Values	0.97

Fair Value Measurements - Defer

Fair Value Measurements - Deferred and Contingent Consideration Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Deferred Consideration (Level 2 Liabilities)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Consideration, beginning balance	$ 5,700	$ 7,400
Additions	0	0
Change in Fair Value	(700)	(1,200)
Payments	0	0
Consideration, ending balance	5,000	6,200
Contingent Consideration (Level 3 Liabilities)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Consideration, beginning balance	84,600	58,100
Additions	0	0
Change in Fair Value	(11,200)	(8,300)
Payments	0	0
Consideration, ending balance	$ 73,400	$ 49,800

Product Revenues, Net - Product

Product Revenues, Net - Product Revenues By Geographic Location (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Product revenues, net	$ 75,500	$ 65,214
US
Disaggregation of Revenue [Line Items]
Product revenues, net	56,349	49,067
Japan
Disaggregation of Revenue [Line Items]
Product revenues, net	14,891	13,156
Europe and rest of world
Disaggregation of Revenue [Line Items]
Product revenues, net	$ 4,260	$ 2,991

Inventory - Schedule of Invento

Inventory - Schedule of Inventory (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Inventory Disclosure [Abstract]
Raw materials	$ 21,943	$ 24,562
Work-in-process	29,359	33,480
Finished goods	31,655	25,206
Inventory, Net	$ 82,957	$ 83,248

Intangibles, Net and Goodwill -

Intangibles, Net and Goodwill - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets estimated useful life (in years)	12 years
Amortization of intangible assets, remainder of 2024	$ 5,100
Amortization of intangible assets, 2025	5,100
Amortization of intangible assets, 2026	5,100
Amortization of intangible assets, 2027	5,100
Amortization of intangible assets, 2028	5,100
Goodwill	$ 136,110	$ 136,110

Intangibles, Net and Goodwill_2

Intangibles, Net and Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Finite-lived Intangible Assets [Roll Forward]
Intangibles, gross			$ 63,704	$ 68,756
Additions	$ 0	$ 0
Amortization	(1,263)	(1,263)
Intangibles, net	62,441	67,493	63,704
Acquired ARIKAYCE R&D
Finite-lived Intangible Assets [Roll Forward]
Intangibles, gross			32,738	37,588
Additions	0	0
Amortization	(1,212)	(1,212)
Intangibles, net	31,526	36,376
Acquired IPR&D
Finite-lived Intangible Assets [Roll Forward]
Intangibles, gross			29,600	29,600
Additions	0	0
Amortization	0	0
Intangibles, net	29,600	29,600
PARI milestones
Finite-lived Intangible Assets [Roll Forward]
Intangibles, gross			$ 1,366	$ 1,568
Additions	0	0
Amortization	(51)	(51)
Intangibles, net	$ 1,315	$ 1,517

Fixed Assets, Net (Details)

Fixed Assets, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 114,633	$ 110,012
Less: accumulated depreciation	(45,973)	(44,628)
Fixed assets, net	$ 68,660	65,384
Lab equipment
Property, Plant and Equipment [Line Items]
Estimated Useful Life (years)	7 years
Fixed assets, gross	$ 23,468	22,660
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Estimated Useful Life (years)	7 years
Fixed assets, gross	$ 6,428	6,428
Computer hardware and software
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 6,106	6,001
Computer hardware and software \| Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life (years)	3 years
Computer hardware and software \| Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life (years)	5 years
Office equipment
Property, Plant and Equipment [Line Items]
Estimated Useful Life (years)	7 years
Fixed assets, gross	$ 89	89
Manufacturing equipment
Property, Plant and Equipment [Line Items]
Estimated Useful Life (years)	7 years
Fixed assets, gross	$ 1,336	1,336
Leasehold improvements
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 37,968	38,049
Leasehold improvements \| Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life (years)	2 years
Leasehold improvements \| Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life (years)	10 years
Construction in progress
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 39,238	$ 35,449

Accounts Payable and Accrued _3

Accounts Payable and Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Accounts payable and other accrued operating expenses	$ 44,018	$ 65,393
Accrued clinical trial expenses	23,754	23,711
Accrued professional fees	16,728	13,885
Accrued technical operation expenses	10,293	9,187
Accrued compensation and employee related costs	23,803	48,933
Accrued royalty and milestones payable	6,514	5,674
Accrued interest payable	2,269	2,175
Revenue Interest Payments payable	3,020	3,347
Accrued sales allowances and related costs	17,159	10,937
Accrued France ATU reimbursement payable	15,896	14,685
Deferred and contingent consideration	15,700	6,700
Other accrued liabilities	10,208	10,360
Total accounts payable and accrued liabilities	$ 189,362	$ 214,987

Leases - Narrative (Details)

Leases - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
Leases - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Lessee, Lease, Description [Line Items]
Variable lease, cost	$ 4.9	$ 0.1
Lease cost, future right-of-use asset	$ 52		$ 49.1
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term	1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term	10 years 10 months

Leases - Lease, costs (Details)

Leases - Lease, costs (Details) - USD ($) $ in Thousands	3 Months Ended
Leases - Lease, costs (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023
Lease, Cost [Abstract]
Finance right-of-use assets obtained in exchange for lease obligations	$ 0	$ 0
Operating right-of-use assets obtained in exchange for lease obligations	$ 5,656	$ 1,751

Debt - Schedule of Long-Term De

Debt - Schedule of Long-Term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Less: current portion of convertible notes	$ (224,194)	$ 0
Total long-term convertible notes	939,081	1,155,313
Convertible notes
Debt Instrument [Line Items]
Term Loan	789,731	788,909
Term Loan
Debt Instrument [Line Items]
Term Loan	$ 373,544	$ 366,404

Debt - Narrative (Details)

Debt - Narrative (Details) $ / shares in Units, $ in Thousands	1 Months Ended			3 Months Ended
	Oct. 31, 2022 USD ($)	May 31, 2021 USD ($) day $ / shares	Jan. 31, 2018 USD ($) day $ / shares	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
Paid-in-kind interest capitalized				$ 6,242	$ 5,456
0.75% convertible senior notes due 2028
Debt Instrument [Line Items]
Initial conversion rate		0.0307692	30.7692
0.75% convertible senior notes due 2028 \| Level 2 \| Carrying Value \| Recurring basis
Debt Instrument [Line Items]
Convertible senior notes				565,500
1.75% convertible senior notes due 2025
Debt Instrument [Line Items]
Initial conversion rate		0.0255384	25.5384
1.75% convertible senior notes due 2025 \| Level 2 \| Carrying Value \| Recurring basis
Debt Instrument [Line Items]
Convertible senior notes				224,200
Term Loan \| Secured Debt
Debt Instrument [Line Items]
Original Term Loan balance	$ 350,000			350,000		$ 350,000
Debt issuance costs, net	$ 15,200
Interest payable	50%
Debt term (in months)	24 months
Proceeds from loans	$ 334,800
Term Loan \| Secured Debt \| Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Interest rate	2.50%
Term Loan \| Secured Debt \| Secured Overnight Financing Rate (SOFR) \| Variable Rate Component Two
Debt Instrument [Line Items]
Interest rate	7.75%
Convertible notes
Debt Instrument [Line Items]
Debt issuance costs, net				10,269		$ 11,091
Convertible senior notes			$ 309,100
Effective interest rate		7.10%	7.60%
Residual equity component of debt			$ 140,900
Convertible notes \| 0.75% convertible senior notes due 2028
Debt Instrument [Line Items]
Original Term Loan balance		$ 575,000
Option to purchase additional debt		75,000
Debt issuance costs, net		15,700		$ 9,500
Net proceeds		$ 559,300
Initial conversion price (in dollars per share) \| $ / shares		$ 32.50
Convertible senior notes		$ 371,600
Remaining discount amortization period (in years)				4 years 2 months 1 day
Convertible notes \| 0.75% convertible senior notes due 2028 \| Conversion Term (i)
Debt Instrument [Line Items]
Threshold trading days \| day		5
Threshold consecutive trading days \| day		5
Threshold percent of stock price trigger		98%
Convertible notes \| 0.75% convertible senior notes due 2028 \| Conversion Term (ii)
Debt Instrument [Line Items]
Threshold trading days \| day		45
Threshold consecutive trading days \| day		10
Threshold percent of stock price trigger		10%
Convertible notes \| 0.75% convertible senior notes due 2028 \| Conversion Term (iii)
Debt Instrument [Line Items]
Threshold trading days following fundamental change \| day		30
Convertible notes \| 0.75% convertible senior notes due 2028 \| Conversion Term (iv)
Debt Instrument [Line Items]
Threshold trading days \| day		20
Threshold consecutive trading days \| day		30
Threshold percent of stock price trigger		130%
Convertible notes \| 1.75% convertible senior notes due 2025
Debt Instrument [Line Items]
Original Term Loan balance			450,000
Option to purchase additional debt			50,000
Debt issuance costs, net			14,200	$ 800
Net proceeds			$ 435,800
Repurchased amount		$ 225,000
Loss on extinguishment of debt		17,700
Initial conversion price (in dollars per share) \| $ / shares			$ 39.16
Convertible senior notes		$ 203,400		$ 238,700
Remaining discount amortization period (in years)				9 months 10 days
Convertible notes \| 1.75% convertible senior notes due 2025 \| Conversion Term (i)
Debt Instrument [Line Items]
Threshold trading days \| day			5
Threshold consecutive trading days \| day			5
Threshold percent of stock price trigger			98%
Convertible notes \| 1.75% convertible senior notes due 2025 \| Conversion Term (ii)
Debt Instrument [Line Items]
Threshold trading days \| day			45
Threshold consecutive trading days \| day			10
Threshold percent of stock price trigger			10%
Convertible notes \| 1.75% convertible senior notes due 2025 \| Conversion Term (iii)
Debt Instrument [Line Items]
Threshold trading days following fundamental change \| day			30
Convertible notes \| 1.75% convertible senior notes due 2025 \| Conversion Term (iv)
Debt Instrument [Line Items]
Threshold trading days \| day			20
Threshold consecutive trading days \| day			30
Threshold percent of stock price trigger			130%

Debt - Components of Debt (Deta

Debt - Components of Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Less: current portion of convertible notes	$ (224,194)	$ 0
Total long-term convertible notes	939,081	1,155,313
Convertible notes
Debt Instrument [Line Items]
Face value of outstanding convertible notes	800,000	800,000
Debt issuance costs	(10,269)	(11,091)
Total long-term convertible notes	$ 565,537	$ 788,909

Debt - Schedule of Carrying Val

Debt - Schedule of Carrying Value of Term Loan Balance (Details) - Term Loan - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Oct. 31, 2022
Debt Instrument [Line Items]
Term Loan	$ 373,544	$ 366,404
Secured Debt
Debt Instrument [Line Items]
Original Term Loan balance	350,000	350,000	$ 350,000
Paid-in-kind interest capitalized	33,779	27,537
Term Loan issuance costs, unamortized	(10,235)	(11,133)
Term Loan	$ 373,544	$ 366,404

Debt - Future Principal Repayme

Debt - Future Principal Repayments of Debt (Details) $ in Thousands	Mar. 31, 2024 USD ($)
Year Ending December 31:
2024	$ 0
2025	225,000
2026	191,890
2027	191,889
2028	575,000
2029 and thereafter	0
Total	$ 1,183,779

Debt - Interest Expense (Detail

Debt - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended
Debt - Interest Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023
Debt Instrument [Line Items]
Amortization of debt issuance costs	$ 1,851	$ 1,724
Swap interest income	(754)	(73)
Total debt interest expense	20,465	19,389
Finance lease interest expense	577	614
Total interest expense	21,042	20,003
Convertible Debt
Debt Instrument [Line Items]
Convertible debt contractual interest expense	2,063	2,063
Term Loan
Debt Instrument [Line Items]
Convertible debt contractual interest expense	12,483	10,911
Royalty Agreements
Debt Instrument [Line Items]
Convertible debt contractual interest expense	$ 4,822	$ 4,764

Royalty Financing Agreement - A

Royalty Financing Agreement - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended
	Oct. 31, 2022	Sep. 01, 2025	Mar. 31, 2024	Dec. 31, 2023	Oct. 01, 2022
Debt Instrument [Line Items]
Royalty financing liability			$ 6,514	$ 5,674
Royalty Agreements
Debt Instrument [Line Items]
Royalty maximum	1.8
Royalty financing liability			$ 3,000	$ 3,300
Royalty Agreements \| Maximum
Debt Instrument [Line Items]
Royalty maximum	1.9
Royalty Agreements \| ARIKAYCE Global Net Sales
Debt Instrument [Line Items]
Royalty percentage					4%
Royalty Agreements \| ARIKAYCE Global Net Sales \| Forecast
Debt Instrument [Line Items]
Royalty percentage		4.50%
Royalty Agreements \| Brensocatib Global Net Sales
Debt Instrument [Line Items]
Royalty percentage	75%
Secured Debt \| Royalty Agreements
Debt Instrument [Line Items]
Proceeds from royalty financing	$ 150,000
Face amount	150,000
Interest payments	150,000
Lenders fees and deal expenses	3,800
Proceeds from royalty financing agreement, net	$ 146,200
Effective interest rate	12.40%

Royalty Financing Agreement - C

Royalty Financing Agreement - Carrying Value of Royalty Financing Agreement (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Royalty Financing Agreement [Roll Forward]
Royalty financing agreement liability - beginning balance	$ 155,034
Royalty financing agreement liability - ending balance	156,967		$ 155,034
Amortization of issuance costs	1,851	$ 1,724
Royalty financing agreement	156,967		155,034
Royalty Agreements
Royalty Financing Agreement [Roll Forward]
Interest expense recognized	4,822	4,764
Secured Debt
Royalty Financing Agreement [Roll Forward]
Amortization of issuance costs	131		521
Secured Debt \| Royalty Agreements
Royalty Financing Agreement [Roll Forward]
Royalty financing agreement liability - beginning balance	158,162	151,538	151,538
Revenue Interest Payments paid and payable	(3,020)		(12,222)
Interest expense recognized	4,822		18,846
Royalty financing agreement liability - ending balance	159,964		158,162
Royalty issuance costs, unamortized - beginning balance	3,128	$ 3,523	3,523
Other	0		(126)
Deferred issuance costs, unamortized - ending balance	2,997		3,128
Royalty financing agreement	$ 159,964		$ 158,162

Shareholders' Equity (Details)

Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands

1 Months Ended

3 Months Ended

12 Months Ended

Aug. 04, 2021

Aug. 31, 2023

Jan. 31, 2023

Oct. 31, 2022

Aug. 31, 2022

Mar. 31, 2024

Sep. 30, 2023

Jun. 30, 2023

Mar. 31, 2023

Sep. 30, 2022

Sep. 30, 2021

Mar. 31, 2021

Dec. 31, 2023

Class of Stock [Line Items]

Common stock, authorized shares (in shares)

500,000,000

Common stock, par value (in dollars per share)

$ 0.01

Common stock, outstanding shares (in shares)

148,560,882

147,977,960

Common stock, issued shares (in shares)

148,560,882

147,977,960

Offering price per share (in dollars per share)

$ 20

Payments of stock issuance costs

$ 16,200

$ 409

$ 0

Preferred stock, authorized (in shares)

200,000,000

Preferred stock, par value (in dollars per share)

$ 0.01

Preferred stock, shares issued (in shares)

Preferred stock, shares outstanding (in shares)

Public Stock Offering

Class of Stock [Line Items]

Shares sold in offering (in shares)

13,750,000

Aggregate net proceeds from stock offering

$ 258,800

ATM Program

Class of Stock [Line Items]

Shares sold in offering (in shares)

6,503,041

Offering price per share (in dollars per share)

$ 24.12

Aggregate net proceeds from stock offering

$ 152,200

Common stock authorized, aggregate gross sales proceeds (up to)

$ 500,000

$ 250,000

Motus

Class of Stock [Line Items]

Common stock shares reserved for issuance (in shares)

9,406,112

Shares issued in acquisition (in shares)

2,889,367

177,203

171,427

177,203

171,427

2,889,367

Contingent consideration

$ 35,000

Adrestia Therapeutics Ltd

Class of Stock [Line Items]

Issuance of common stock for business acquisition (in shares)

3,430,867

Vertuis Bio, Inc.

Class of Stock [Line Items]

Common stock shares reserved for issuance (in shares)

550,000

Issuance of common stock for business acquisition (in shares)

500,000

Contingent consideration

$ 1,000

Convertible notes

Class of Stock [Line Items]

Common stock shares reserved for issuance (in shares)

23,438,430

Common stock options

Class of Stock [Line Items]

Common stock shares reserved for issuance (in shares)

24,098,410

Unvested RS and RSUs

Class of Stock [Line Items]

Common stock shares reserved for issuance (in shares)

3,058,943

PSUs

Class of Stock [Line Items]

Common stock shares reserved for issuance (in shares)

666,382

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) - USD ($)			3 Months Ended
Stock-Based Compensation - Narrative (Details) - USD ($)	May 12, 2020	May 15, 2018	Mar. 31, 2024	Mar. 31, 2023
Stock-Based Compensation
Inducement stock options granted to new employees (in shares)			358,140
Common stock options
Stock-Based Compensation
Unrecognized compensation expense related to unvested stock options			$ 148,000,000
Options outstanding (in shares)			114,780
Unvested RS and RSUs
Stock-Based Compensation
Unrecognized compensation expense related to unvested RSU awards			$ 55,800,000
Performance options
Stock-Based Compensation
Options outstanding, nonvested (in shares)			266,550
Unrecognized compensation expense			$ 10,400,000
Potential award payout			100%
Allocated share-based compensation expense			$ 0	$ 0
2019 Incentive Plan
Stock-Based Compensation
Shares available for grant (in shares)			4,705,225
2018 ESPP
Stock-Based Compensation
Number of additional shares authorized (in shares)		1,200,000
Shares of common stock, maximum authorized for issuance (in shares)		1,000,000
Percentage of outstanding shares		2%
2019 Incentive Plan
Stock-Based Compensation
Number of additional shares authorized (in shares)	3,000,000

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock and Restricted Stock Units (Details) - Stock options and RSUs - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Stock-Based Compensation
Allocated share-based compensation expense	$ 21.5	$ 16.4
Research and development
Stock-Based Compensation
Allocated share-based compensation expense	10.4	7.9
Selling, general and administrative
Stock-Based Compensation
Allocated share-based compensation expense	$ 11.1	$ 8.5

Income Taxes (Details)

Income Taxes (Details) - USD ($)	3 Months Ended
Income Taxes (Details) - USD ($)	Mar. 31, 2024	Mar. 31, 2023
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 589,000	$ 483,000
Deferred tax benefit	0
Unrecognized tax benefits, interest and penalties accrued	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Rent expense charged to operations	$ 3.1	$ 2.2

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details) $ / shares in Units, $ in Thousands			1 Months Ended					3 Months Ended
	Aug. 04, 2021 USD ($) shares	May 24, 2021 days	Aug. 31, 2023 shares	Jun. 30, 2023 USD ($) $ / shares shares	Jan. 31, 2023 USD ($) $ / shares shares	Aug. 31, 2022 shares	Aug. 31, 2021 USD ($) $ / shares shares	Mar. 31, 2024 USD ($)	Sep. 30, 2023 shares	Sep. 30, 2022 shares	Sep. 30, 2021 shares
Business Acquisition [Line Items]
Share price (in usd per share) \| $ / shares				$ 21.10	$ 18.50
Consecutive trading day period \| days		45
Motus and AlgaeneX
Business Acquisition [Line Items]
Aggregate value							$ 165,500
Motus
Business Acquisition [Line Items]
Shares issued in acquisition (in shares) \| shares	2,889,367		177,203			171,427			177,203	171,427	2,889,367
Shares issued upon milestone achievements (in shares) \| shares							5,348,572
Contingent consideration	$ 35,000
Share price used to calculate issuable shares (in dollars per share) \| $ / shares							$ 27.11
Motus \| First anniversary of closing date
Business Acquisition [Line Items]
Shares issued in acquisition (in shares) \| shares							184,433
Motus \| Second anniversary of closing date
Business Acquisition [Line Items]
Shares issued in acquisition (in shares) \| shares							184,433
Motus \| Third anniversary of closing date
Business Acquisition [Line Items]
Shares issued in acquisition (in shares) \| shares							184,433
AlgaeneX
Business Acquisition [Line Items]
Shares issued upon milestone achievements (in shares) \| shares	368,867
Cash paid in acquisition							$ 1,500
Share price used to calculate issuable shares (in dollars per share) \| $ / shares							$ 27.11
Adrestia Therapeutics Ltd
Business Acquisition [Line Items]
Shares issued in asset acquisition (in shares) \| shares				3,430,867
Asset acquisition, consideration transferred				$ 72,400
Contingent payment, value				$ 326,500
Vertuis Bio, Inc.
Business Acquisition [Line Items]
Shares issued in asset acquisition (in shares) \| shares					500,000
Asset acquisition, consideration transferred					$ 10,250
Contingent payment, value					1,000
IPR&D expense								$ 76,500
Vertuis Bio, Inc. \| Milestone Event 1
Business Acquisition [Line Items]
Contingent payment, value					1,000
Vertuis Bio, Inc. \| Milestone Event 2
Business Acquisition [Line Items]
Contingent payment, value					23,000
Vertuis Bio, Inc. \| Milestone Event 3
Business Acquisition [Line Items]
Contingent payment, value					$ 63,800

Acquisitions - Asset Acquisitio

Acquisitions - Asset Acquisition (Details) - Vertuis Bio, Inc. $ in Thousands	1 Months Ended
	Jan. 31, 2023 USD ($)
Business Acquisition [Line Items]
Shares of Insmed common stock issued on closing	$ 9,250
Shares of Insmed common stock issuable on July 1, 2024	1,000
Total purchase price	$ 10,250