Summary of Significant Accounting Policies	3 Months Ended
Mar. 31, 2026
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying condensed consolidated financial statements of the Company for the three months ended March 31, 2026 and 2025 are unaudited and have been prepared on a basis substantially consistent with the audited financial statements for the year ended December 31, 2025. The year-end consolidated balance sheet data, which is presented for comparative purposes, was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the U.S. (commonly referred to as “GAAP”). In the opinion of management, the condensed consolidated financial statements include all adjustments of a normal recurring nature that are necessary to state fairly the results of operations for the reported periods. The accompanying condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto of the Company, which are contained in the Annual Report. The results of the Company’s operations for any interim period are not necessarily indicative of the results of the Company’s operations for any other interim period or for any full fiscal year. Principles of Consolidation The accompanying condensed consolidated financial statements include the accounts of Alkermes plc and its wholly-owned subsidiaries as disclosed in Note 2, Summary of Significant Accounting Policies in the “Notes to Consolidated Financial Statements” accompanying the Annual Report. Intercompany accounts and transactions have been eliminated. Columns and rows within tables may not sum due to rounding. Use of Estimates The preparation of the Company’s condensed consolidated financial statements in accordance with GAAP requires that Company management make estimates, judgments and assumptions that may affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities. On an ongoing basis, the Company evaluates its estimates, judgments and methodologies, including, but not limited to, those related to revenue from contracts with its customers and related allowances, impairment and amortization of intangibles and long-lived assets, inventory, share-based compensation, income taxes including the valuation allowance for deferred tax assets, valuation of the Avadel Acquisition, investments, contingent consideration and litigation. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results may differ from these estimates under different conditions or using different assumptions. Business Combinations In accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 805, Business Combinations (“Topic 805”), acquisitions that meet the definition of a business are recorded using the acquisition method of accounting. The Company recognizes and measures the identifiable assets acquired, liabilities assumed and any non-controlling interest as of the acquisition date at fair value. The excess, if any, of the fair value of total consideration transferred in a business combination over the fair value of identifiable assets acquired, liabilities assumed and any non-controlling interest is recognized as goodwill. Transaction costs incurred as a result of a business combination other than costs related to the issuance of debt or equity securities are recorded in the period the costs are incurred. Contingent Consideration Contingent consideration in a business combination may consist of development, regulatory and/or commercial milestone payments and is included as part of the acquisition cost and recognized at fair value as of the acquisition date. Fair value is generally estimated by using a probability-weighted discounted cash flow approach resulting from contingent consideration and is re-measured at each reporting date until the contingency is resolved. Changes in fair value are recognized within “Operating (loss) income” in the accompanying condensed consolidated statements of operations and comprehensive (loss) income. Reclassification The Company reclassified certain prior year amounts on the consolidated balance sheet to conform to the current year presentation. These reclassifications had no impact on the previously reported total assets, liabilities or shareholders’ equity. Intangible Assets Intangible assets acquired in business combinations, including developed technology, product rights, licenses, and in-process research and development (“IPR&D”), are recorded at fair value as of the acquisition date. Definite-lived identifiable intangible assets are amortized based on the proportion of expected excess earnings over their estimated economic useful life. This method reflects the pattern in which the economic benefits of the intangible assets are expected to be realized. Acquired IPR&D projects that have not yet received regulatory approval are considered indefinite-lived intangible assets and are required to be capitalized as indefinite-lived intangible assets until completion of the IPR&D project or abandonment. IPR&D projects are not amortized but are tested annually for impairment or more frequently if indicators arise. Upon completion of the development project, an impairment assessment is performed prior to amortizing the asset over its estimated useful life. IPR&D assets related to abandoned IPR&D projects are fully impaired. Segment Information Operating segments are defined as components of an enterprise engaging in business activities for which separate financial information is available and regularly reviewed by the chief operating decision maker (“CODM”) in deciding how to allocate resources and in assessing performance. The Company has utilized the management approach to determine that the Company is managed as one segment on a consolidated basis and is in the business of developing, manufacturing and commercializing medicines designed to help people living with complex and difficult-to-treat psychiatric and neurological disorders. The Company’s CODM, the Chairman and Chief Executive Officer, reviews the Company’s operating results on an aggregate basis and manages the Company’s operations as a single operating unit. The Company’s CODM measures profitability on a reportable segment basis using net income and utilizes this information in allocating resources and in assessing performance by monitoring budget versus actual results. Please refer to Note 17, Segment Reporting, in these “Notes to Condensed Consolidated Financial Statements” in this Form 10-Q for further information. New Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB or other standard-setting bodies that are adopted by the Company on or prior to the specified effective date. Unless otherwise described in this Form 10-Q, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. In November 2024, the FASB issued Accounting Standards Update (“ASU”) 2024-03, Income Statement—Reporting Comprehensive Income-Expense Disaggregation Disclosures, to improve disclosures about a public business entity’s expenses and address requests from investors for more detailed information about the types of expenses (including purchases of inventory, employee compensation, depreciation, amortization and depletion) in commonly-presented expense captions, such as cost of sales, selling, general and administrative expenses, and research and development. All disclosure requirements under this guidance are required for public business entities and effective for annual periods beginning after December 15, 2026 and interim periods beginning after December 15, 2027. Early adoption is permitted and the amendments in this guidance will be applied prospectively to financial statements for periods after the effective dates. The Company is currently evaluating the impact this ASU will have on its consolidated financial statements and related disclosures. In September 2025, the FASB issued ASU 2025-06, Targeted Improvements to the Accounting for Internal-Use Software. This ASU updates the requirements for capitalization of internal-use software, removing all reference to prescriptive and sequential software development stages (referred to as “project stages”). This ASU is effective for annual periods beginning after December 15, 2027, and for interim periods within those fiscal years. The Company is currently assessing the impact this ASU will have on its consolidated financial statements and related disclosures. In December 2025, the FASB issued ASU 2025-11, Interim Reporting. The amendments in this update clarify current interim disclosure requirements and provide a comprehensive list of required interim disclosures. The update also incorporates a disclosure principle that requires entities to disclose events that occur after the end of the reporting period. This update is effective for interim periods within annual periods beginning after December 15, 2027, though early adoption is permitted. The Company is currently assessing the impact this ASU will have on its consolidated financial statements and related disclosures.

Basis of Presentation

The accompanying condensed consolidated financial statements of the Company for the three months ended March 31, 2026 and 2025 are unaudited and have been prepared on a basis substantially consistent with the audited financial statements for the year ended December 31, 2025. The year-end consolidated balance sheet data, which is presented for comparative purposes, was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the U.S. (commonly referred to as “GAAP”). In the opinion of management, the condensed consolidated financial statements include all adjustments of a normal recurring nature that are necessary to state fairly the results of operations for the reported periods.

The accompanying condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto of the Company, which are contained in the Annual Report. The results of the Company’s operations for any interim period are not necessarily indicative of the results of the Company’s operations for any other interim period or for any full fiscal year.

Principles of Consolidation

The accompanying condensed consolidated financial statements include the accounts of Alkermes plc and its wholly-owned subsidiaries as disclosed in Note 2, Summary of Significant Accounting Policies in the “Notes to Consolidated Financial Statements” accompanying the Annual Report. Intercompany accounts and transactions have been eliminated. Columns and rows within tables may not sum due to rounding.

Use of Estimates

The preparation of the Company’s condensed consolidated financial statements in accordance with GAAP requires that Company management make estimates, judgments and assumptions that may affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities. On an ongoing basis, the Company evaluates its estimates, judgments and methodologies, including, but not limited to, those related to revenue from contracts with its customers and related allowances, impairment and amortization of intangibles and long-lived assets, inventory, share-based compensation, income taxes including the valuation allowance for deferred tax assets, valuation of the Avadel Acquisition, investments, contingent consideration and litigation. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results may differ from these estimates under different conditions or using different assumptions.

Business Combinations

In accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 805, Business Combinations (“Topic 805”), acquisitions that meet the definition of a business are recorded using the acquisition method of accounting. The Company recognizes and measures the identifiable assets acquired, liabilities assumed and any non-controlling interest as of the acquisition date at fair value. The excess, if any, of the fair value of total consideration transferred in a business combination over the fair value of identifiable assets acquired, liabilities assumed and any non-controlling interest is recognized as goodwill. Transaction costs incurred as a result of a business combination other than costs related to the issuance of debt or equity securities are recorded in the period the costs are incurred.

Contingent Consideration

Contingent consideration in a business combination may consist of development, regulatory and/or commercial milestone payments and is included as part of the acquisition cost and recognized at fair value as of the acquisition date. Fair value is generally estimated by using a probability-weighted discounted cash flow approach resulting from contingent consideration and is re-measured at each reporting date until the contingency is resolved. Changes in fair value are recognized within “Operating (loss) income” in the accompanying condensed consolidated statements of operations and comprehensive (loss) income.

Intangible Assets

Intangible assets acquired in business combinations, including developed technology, product rights, licenses, and in-process research and development (“IPR&D”), are recorded at fair value as of the acquisition date. Definite-lived identifiable intangible assets are amortized based on the proportion of expected excess earnings over their estimated economic useful life. This method reflects the pattern in which the economic benefits of the intangible assets are expected to be realized.

Acquired IPR&D projects that have not yet received regulatory approval are considered indefinite-lived intangible assets and are required to be capitalized as indefinite-lived intangible assets until completion of the IPR&D project or abandonment. IPR&D projects are not amortized but are tested annually for impairment or more frequently if indicators arise. Upon completion of the development project, an impairment assessment is performed prior to amortizing the asset over its estimated useful life. IPR&D assets related to abandoned IPR&D projects are fully impaired.

Segment Information

Operating segments are defined as components of an enterprise engaging in business activities for which separate financial information is available and regularly reviewed by the chief operating decision maker (“CODM”) in deciding how to allocate resources and in assessing performance. The Company has utilized the management approach to determine that the Company is managed as one segment on a consolidated basis and is in the business of developing, manufacturing and commercializing medicines designed to help people living with complex and difficult-to-treat psychiatric and neurological disorders. The Company’s CODM, the Chairman and Chief Executive Officer, reviews the Company’s operating results on an aggregate basis and manages the Company’s operations as a single operating unit. The Company’s CODM measures profitability on a reportable segment basis using net income and utilizes this information in allocating resources and in assessing performance by monitoring budget versus actual results. Please refer to Note 17, Segment Reporting, in these “Notes to Condensed Consolidated Financial Statements” in this Form 10-Q for further information.

New Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the FASB or other standard-setting bodies that are adopted by the Company on or prior to the specified effective date. Unless otherwise described in this Form 10-Q, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption.

In November 2024, the FASB issued Accounting Standards Update (“ASU”) 2024-03, Income Statement—Reporting Comprehensive Income-Expense Disaggregation Disclosures, to improve disclosures about a public business entity’s expenses and address requests from investors for more detailed information about the types of expenses (including purchases of inventory, employee compensation, depreciation, amortization and depletion) in commonly-presented expense captions, such as cost of sales, selling, general and administrative expenses, and research and development. All disclosure requirements under this guidance are required for public business entities and effective for annual periods beginning after December 15, 2026 and interim periods beginning after December 15, 2027. Early adoption is permitted and the amendments in this guidance will be applied prospectively to financial statements for periods after the effective dates. The Company is currently evaluating the impact this ASU will have on its consolidated financial statements and related disclosures.

In September 2025, the FASB issued ASU 2025-06, Targeted Improvements to the Accounting for Internal-Use Software. This ASU updates the requirements for capitalization of internal-use software, removing all reference to prescriptive and sequential software development stages (referred to as “project stages”). This ASU is effective for annual periods beginning after December 15, 2027, and for interim periods within those fiscal years. The Company is currently assessing the impact this ASU will have on its consolidated financial statements and related disclosures.

In December 2025, the FASB issued ASU 2025-11, Interim Reporting. The amendments in this update clarify current interim disclosure requirements and provide a comprehensive list of required interim disclosures. The update also incorporates a disclosure principle that requires entities to disclose events that occur after the end of the reporting period. This update is effective for interim periods within annual periods beginning after December 15, 2027, though early adoption is permitted. The Company is currently assessing the impact this ASU will have on its consolidated financial statements and related disclosures.