10-K – 2026-02-06 – biib-20251231.htm

Our operating leases are reflected in operating lease assets, accrued expense and other and long-term operating lease liabilities in our consolidated balance sheets. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term.
We also have real estate lease agreements which are subleased to third parties. Operating leases for which we are the sublessor are included in accrued expense and other and other long-term liabilities in our consolidated balance sheets. We recognize sublease income on a straight-line basis over the lease term in our consolidated statements of income.
For additional information on our leases, please read Note 12, Leases , to these consolidated financial statements.
Intangible Assets
Our intangible assets primarily consist of completed technology (comprising of acquired and in-licensed rights and patents, and developed technology), IPR&D acquired after January 1, 2009, acquired priority review vouchers and trademarks and trade names. Our intangible assets are recorded at fair value at the time of their acquisition and are stated in our consolidated balance sheets net of accumulated amortization and impairments, if applicable.
Intangible assets related to completed technology are amortized over their estimated useful lives using the economic consumption method if anticipated future revenue can be reasonably estimated. The straight-line method is used when revenue cannot be reasonably estimated. Amortization is recorded within amortization and impairment of acquired intangible assets in our consolidated statements of income.
The economic consumption method is based on revenue generated from the products underlying the related intangible assets. An analysis of the anticipated lifetime revenue of our marketed products is performed annually during our long-range planning cycle and whenever events or changes in circumstances would significantly affect anticipated lifetime revenue of the relevant products.
Intangible assets related to trademarks, trade names, IPR&D prior to commercialization and priority review vouchers are not amortized because they have indefinite lives; however, they are subject to review for impairment. We review our intangible assets with indefinite lives for impairment annually, as of October 31, and whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable.
Acquired In-process Research and Development
Acquired IPR&D represents the fair value assigned to research and development assets that have not reached technological feasibility. The value assigned to acquired IPR&D is determined by estimating the costs to develop the acquired technology into commercially viable products, estimating the resulting revenue from the projects and discounting the net cash flow to present value. The revenue and cost projections used to value acquired IPR&D are, as applicable, reduced based on the probability of success of developing a new drug. Additionally, the projections consider the relevant market sizes and growth factors, expected trends in technology and the nature and expected timing of new product introductions by us and our competitors. The rates utilized to discount the net cash flow to present value are commensurate with the stage of development of the projects and uncertainties in the economic estimates used in the projections. Upon the acquisition of IPR&D, we complete an assessment of whether our acquisition constitutes the purchase of a single asset or a group of assets. We consider multiple factors in this assessment, including the nature of the technology acquired, the presence or absence of separate cash flow, the development process and stage of completion, quantitative significance and our rationale for entering into the transaction.
If we acquire a business as defined under applicable accounting standards, then the acquired IPR&D is capitalized as an intangible asset. If we acquire an asset or group of assets with no alternative future use that do not meet the definition of a business under applicable accounting standards, then the acquired IPR&D is expensed on its acquisition date. Future costs to develop these assets are recorded to research and development expense within our consolidated statements of income as they are incurred.
When performing our impairment assessment, we calculate the fair value using the same methodology as described above. If the carrying value of our acquired IPR&D exceeds its fair value, then the intangible asset is written down to its fair value. Changes in estimates and assumptions used in determining the fair value of our acquired IPR&D could result in an impairment. Acquired IPR&D impairments are recorded within amortization and impairment of acquired intangible assets in our consolidated statements of income.
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Goodwill
Goodwill represents the difference between the purchase price and the fair value of the identifiable tangible and intangible net assets when accounted for using the purchase method of accounting. Goodwill is not amortized, but is reviewed for impairment annually, as of October 31, and whenever events or changes in circumstances indicate that the carrying value of the goodwill may not be recoverable.
We compare the fair value of our reporting unit to its carrying value. If the carrying value of the net assets assigned to the reporting unit exceeds the fair value of our reporting unit, we would record an impairment loss equal to the difference. As described in Note 25, Segment Information, to these consolidated financial statements, we operate as one operating segment, which is our only reporting unit.
Impairment of Long-Lived Assets
Long-lived assets to be held and used, including property, plant and equipment, and definite-lived intangible assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets or asset group may not be recoverable.
Determination of recoverability is based on an estimate of undiscounted future cash flow resulting from the use of the assets and eventual disposition. In the event that such cash flow is not expected to be sufficient to recover the carrying amount of the assets, the assets are written-down to their fair values. Long-lived assets to be disposed of are carried at fair value less costs to sell.
Contingent Consideration
The consideration for our acquisitions often includes future payments that are contingent upon the occurrence of a particular event or events. We record an obligation for such contingent payments at fair value on the acquisition date. We estimate the fair value of contingent consideration obligations through valuation models that incorporate probability-adjusted assumptions related to the achievement of the milestones and thus likelihood of making related payments. We revalue our contingent consideration obligations each reporting period. Changes in the fair value of our contingent consideration obligations are recognized in our consolidated statements of income. Changes in the fair value of the contingent consideration obligations can result from changes to one or multiple inputs, including adjustments to the discount rates, changes in the amount or timing of expected expenditures associated with product development, changes in the amount or timing of cash flow and reserves associated with products upon commercialization, changes in the assumed achievement or timing of any cumulative sales-based and development milestones, changes in the probability of certain clinical events and changes in the assumed probability associated with regulatory approval.
Discount rates in our valuation models represent a measure of the credit risk associated with settling the liability. The period over which we discount our contingent obligations is based on the current development stage of the product candidates, our specific development plan for that product candidate adjusted for the probability of completing the development step and when the contingent payments would be triggered. In estimating the probability of success, we utilize data regarding similar milestone events from several sources, including industry studies and our own experience. These fair value measurements are based on significant inputs not observable in the market. Significant judgment is employed in determining the appropriateness of these assumptions as of the acquisition date and for each subsequent period.
Derivative Instruments and Hedging Activities
Cash Flow and Fair Value Derivative Instruments
We recognize all derivative instruments as either assets or liabilities at fair value in our consolidated balance sheets. Changes in the fair value of our derivative instruments are recognized each period in current earnings or AOCI, depending on whether the derivative instrument is designated as part of a hedge transaction and, if so, the type of hedge transaction. We classify the cash flow from these instruments in the same category as the cash flow from the hedged items. We do not hold or issue derivative instruments for trading or speculative purposes.
We assess at inception and on an ongoing basis, whether the derivative instruments that are used in hedging transactions are highly effective in offsetting the changes in cash flow or fair values of the hedged items. We exclude the forward points portion of the derivative instruments used in a hedging transaction from the effectiveness test and record the fair value gain or loss related to this portion each period in our consolidated statements of income in
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the same line as the underlying hedged item. If we determine that a forecasted transaction is no longer probable of occurring, we discontinue hedge accounting for the affected portion of the hedge instrument, and any related unrealized gain or loss on the contract is recognized in current earnings.
Translation of Foreign Currencies
The functional currency for most of our foreign subsidiaries is their local currency. For our non-U.S. subsidiaries that transact in a functional currency other than the U.S. dollar, assets and liabilities are translated at current rates of exchange at the balance sheet date. Income and expense items are translated at the average foreign currency exchange rates for the period. Adjustments resulting from the translation of the financial statements of our foreign operations into U.S. dollars are excluded from the determination of net income and are recorded in AOCI, as a separate component of equity. For subsidiaries where the functional currency of the assets and liabilities differ from the local currency, non-monetary assets and liabilities are translated at the rate of exchange in effect on the date assets were acquired while monetary assets and liabilities are translated at current rates of exchange as of the balance sheet date. Income and expense items are translated at the average foreign currency rates for the period. Translation adjustments of these subsidiaries are included in other (income) expense, net in our consolidated statements of income.
Royalty Cost of Sales
We make royalty payments to a number of third parties under license or purchase agreements associated with our acquisition of intellectual property. These royalty payments are typically calculated as a percentage (royalty rate) of the sales of our products in a particular year. That royalty rate may remain constant, increase or decrease within each year based on the total amount of sales during the annual period. Each quarterly period, we estimate our total royalty obligation for the full year and recognize the proportional amount as cost of sales based on actual quarterly sales as a percentage of full year estimated sales. For example, if the level of net sales in any calendar year increases the royalty rate within the year, we will record our cost of sales at an even rate over the year, based on the estimated blended royalty rate.
Accounting for Share-Based Compensation
Our share-based compensation programs grant awards that have included stock options, time-vested RSUs, performance-vested stock units that vest based upon meeting both a performance condition and a service condition and shares issued under our ESPP. Compensation expense is recognized based on the estimated fair value of the awards at grant date. We recognize compensation expense for the number of awards expected to vest after taking into consideration an estimate of award forfeitures over the requisite service period, which is generally the vesting period. Where awards are made with non-substantive vesting periods (for instance, where a portion of the award vests upon retirement eligibility), we estimate and recognize expense based on the period from the grant date to the date the employee becomes retirement eligible.
The fair values of our stock option grants are estimated as of the date of grant using a Black-Scholes option valuation model. The estimated fair values of the stock options are then expensed over the options' vesting periods.
The fair values of our RSUs are based on the market value of our stock on the date of grant. Compensation expense for RSUs is recognized straight-line over the applicable service period. If the service condition is not met or not expected to be met, any compensation expense previously recognized to date associated with the awards will be reversed.
The fair values of our PSUs that settle in stock and have market-based metrics are estimated using a lattice model with a Monte Carlo simulation. Compensation expense is recognized straight-line over the applicable service period for these awards. The probability of actual shares expected to be earned is considered in the grant date valuation, therefore the expense is not adjusted to reflect the actual units earned.
The fair values of PSUs that settle in stock and do not have market-based metrics are based on the market value of our stock on the date of grant. Compensation expense is recognized for the number of units expected to be earned after assessing the probability that certain performance criteria will be met and the targeted payout level associated with the performance criteria expected to be achieved. Cumulative adjustments are recorded each quarter to reflect the estimated outcome of the performance-related conditions until the date results are determined and settled. If the performance criteria are not met or not expected to be met, any compensation expense previously recognized to date associated with the awards will be reversed.
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Research and Development Expense
Research and development expense consists of expenses incurred in performing research and development activities, which include compensation and benefits, facilities and overhead expense, clinical trial expense and fees paid to CROs, clinical supply and manufacturing expense, fair value step-up adjustment amortization of inventory used for clinical purposes and other outside expense. Research and development expense is expensed as incurred. Payments we make for research and development services prior to the services being rendered are recorded as prepaid assets in our consolidated balance sheets and are expensed as the services are provided. We also accrue the costs of ongoing clinical trials associated with programs that have been terminated or discontinued for which there is no future economic benefit at the time the decision is made to terminate or discontinue the program.
From time to time, we enter into development agreements in which we share expenses with a collaborative partner. We record payments received from our collaborative partners for their share of the development costs as a reduction of research and development expense, except as discussed in Note 19, Collaborative and Other Relationships, to these consolidated financial statements. Expenses incurred by Genentech in the ongoing development of RITUXAN, GAZYVA, LUNSUMIO and other products for which an initial indication has been approved are not recorded as research and development expense, but rather reduce our share of profits recorded as a component of revenue from anti-CD20 therapeutic programs.
Acquired In-process Research and Development, Upfront and Milestone Expense
Acquired in-process research and development, upfront and milestone expense consists of upfront fees and milestones paid to third-party collaborators as well as charges associated with the acquisition of an asset or group of assets with no alternative future use that did not meet the definition of a business under applicable accounting standards. Upfront and milestone payments made to third-party collaborators are expensed as incurred up to the point of regulatory approval. Milestone payments made upon regulatory approval are capitalized and amortized over the remaining useful life of the related product.
Selling, General and Administrative Expense
Selling, general and administrative expense is primarily comprised of compensation and benefits associated with sales and marketing, finance, human resources, legal, information technology and other administrative personnel, outside marketing, advertising and legal expense and other general and administrative costs.
Advertising costs are expensed as incurred. For the years ended December 31, 2025, 2024 and 2023, advertising costs t otaled approximately $ 71.9 million , $ 66.8 million and $ 71.4 million, respectively.
Income Taxes
The provision for income taxes includes federal, state, local and foreign taxes. Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the estimated future tax consequences of temporary differences between the financial statement carrying amounts and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the year in which the temporary differences are expected to be recovered or settled. We evaluate the realizability of our deferred tax assets and establish a valuation allowance when it is more likely than not that all or a portion of deferred tax assets will not be realized. We recognize deferred taxes associated with our GILTI tax calculations.
The income tax consequences from the intra-entity transfers of inventory within our consolidated group, both current and deferred, are recorded as a prepaid tax or deferred charge and recognized through our consolidated statements of income when the inventory is sold to a third party. The income tax consequences from the intra-entity transfer of assets other than inventory and associated changes to deferred taxes are recognized when the transfer occurs.
We account for uncertain tax positions using a “more likely than not” threshold for recognizing and resolving uncertain tax positions. We evaluate uncertain tax positions on a quarterly basis and consider various factors including, but not limited to, changes in tax law, the measurement of tax positions taken or expected to be taken in tax returns, the effective settlement of matters subject to audit, information obtained during in process audit activities and changes in facts or circumstances related to a tax position. We also accrue for potential interest and penalties related to unrecognized tax benefits in income tax (benefit) expense in our consolidated statements of income.
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Contingencies
We are currently involved in various claims and legal proceedings. Loss contingency provisions are recorded if the potential loss from any claim, asserted or unasserted, or legal proceeding is considered probable and the amount can be reasonably estimated or a range of loss can be determined. These accruals represent management’s best estimate of probable loss. Disclosure also is provided when it is reasonably possible that a loss will be incurred or when it is reasonably possible that the amount of a loss will exceed the recorded provision. On a quarterly basis, we review the status of each significant matter and assess its potential financial exposure. Significant judgment is required in both the determination of probability and as to whether an exposure is reasonably estimable. Because of uncertainties related to these matters, accruals are based only on the best information available at the time. As additional information becomes available, we reassess the potential liability related to pending claims and litigation and may change our estimates. Legal costs associated with legal proceedings are expensed when incurred.
Earnings per Share
Basic earnings per share is computed by dividing undistributed net income attributable to Biogen Inc. by the weighted-average number of common shares outstanding during the period. Diluted earnings per share is computed based on the treasury method by dividing net income by the weighted-average number of common shares outstanding during the period plus potentially dilutive common equivalent shares outstanding.
Business Combinations
Business combinations are recorded using the acquisition method of accounting. The results of operations of the acquired company are included in our results of operations beginning on the acquisition date, and assets acquired and liabilities assumed are recognized on the acquisition date at their respective fair values. Any excess of consideration transferred over the net carrying value of the assets acquired and liabilities assumed as of the acquisition date is recognized as goodwill.
We use the multi-period excess earnings method, which is a form of the income approach, utilizing post-tax cash flow and discount rates in estimating the fair value of identifiable intangible assets acquired when allocating the purchase consideration paid for the acquisition. The estimates of the fair value of identifiable intangible assets involve significant judgment by management and include assumptions with measurement uncertainty, such as the amount and timing of projected cash flow, long-term sales forecasts, discount rates and additionally for IPR&D intangible assets, the timing and probability of regulatory and commercial success.
We use the net realizable value method in estimating the fair value of acquired finished goods and work-in-process inventory. Raw materials acquired are valued using the replacement cost method.
Transaction and restructuring costs related to business combinations are expensed as incurred. The fair value of assets acquired and liabilities assumed in certain cases may be subject to revision based on the final determination of fair value during a period of time not to exceed 12 months from the acquisition date. If we determine the assets acquired do not meet the definition of a business, the transaction will be accounted for as an asset acquisition rather than a business combination.
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New Accounting Pronouncements
From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies that we adopt as of the specified effective date. Unless otherwise discussed below, we do not believe that the adoption of recently issued standards have or may have a material impact on our consolidated financial statements or disclosures.

Standard Description Effective Date Effects on the Financial Statements
ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures
This standard establishes incremental disaggregation of income tax disclosures pertaining to the effective tax rate reconciliation and income taxes paid. The amendments in this update are required to be applied on a prospective basis with the option to apply it retrospectively.
Annual reporting for fiscal years beginning after December 15, 2024. Early adoption is permitted.
We adopted this standard and applied the disclosure requirements on a prospective basis effective for the year ended December 31, 2025. The adoption did not have a material impact on our consolidated financial position or results of operations. Refer to Note 17, Income Taxes , for our updated income tax disclosure.

ASU No. 2024-03, Income Statement (Subtopic 220-40): Reporting Comprehensive Income - Expense Disaggregation Disclosures
This standard requires disclosure in the notes to the financial statements, at each interim and annual reporting period, of specified information about certain costs and expense including purchases of inventory, employee compensation, depreciation and intangible asset amortization included in each relevant expense caption. This standard also requires a qualitative description of the amounts remaining in relevant expense captions that are not separately disaggregated, as well as disclosure of the total amount of selling expenses, and, in annual reporting periods, an entity’s definition of selling expenses.
Annual reporting for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted.
We are currently evaluating the potential impact that this new standard will have on our consolidated financial statements and related disclosures, and expect to apply this standard prospectively upon adoption.

ASU No. 2025-06, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software This standard modernizes the accounting for software costs, including updating guidance on the recognition and measurement of costs incurred in connection with development and implementation activities related to internal-use software. Annual reporting for fiscal periods beginning after December 15, 2027, and interim periods within those annual reporting periods. Early adoption is permitted. We are currently evaluating the potential impact that this new standard will have on our consolidated financial statements and related disclosures.
ASU No. 2025-07, Derivatives and Hedging (Topic 815) and Revenue from Contracts with Customers (Topic 606): Derivatives Scope Refinements and Scope Clarification for Share-Based Noncash Consideration from a Customer in a Revenue Contract This standard refines and expands the existing scope exceptions that exclude certain contracts, including certain R&D funding arrangements, from derivative accounting, and clarifies the accounting for share-based noncash consideration received from a customer. Annual reporting for fiscal years beginning after December 15, 2026, and interim periods within those annual reporting periods. Early adoption is permitted. We have early adopted this new standard on a modified retrospective basis as of January 1, 2025. Adoption did not have a material impact on our condensed consolidated financial statements and related disclosures.

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Note 2:
Acquisitions

Alcyone Therapeutics, Inc.
In November 2025 we completed the acquisition of all of the issued and outstanding shares of Alcyone Therapeutics, Inc., a clinical-stage biotechnology company focused on pediatric care through precision CNS therapeutics and dosing platforms. Alcyone's lead asset is ThecaFlex DRx, an implantable subcutaneous port and catheter device being investigated for the intrathecal delivery of ASOs, including SPINRAZA, which is designed to provide an alternative to repeat lumbar punctures in chronic intrathecal administration of medicines.
Total consideration for this transaction, which was recorded in acquired in-process research and development, upfront and milestone expense in our consolidated statements of income for the year ended December 31, 2025, was approximately $ 85.0  million, comprising a $ 50.0  million payment made upon closing and a $ 35.0 million payment that was considered probable as of December 31, 2025, and made upon FDA approval of a supplemental application in January 2026.
We may pay additional development and regulatory milestone payments to the former shareholders of Alcyone of up to a total of $ 75.0  million if approval is received for ThecaFlex DRx administration of SPINRAZA or other additional pipeline products.
We accounted for this transaction as an asset acquisition as the value being acquired primarily relates to a single asset. U nder the terms of this acquisition, we will oversee the end-to-end development, manufacturing and commercialization of ThecaFlex DRx .
Alcyone's remaining therapeutic assets were divested from Alcyone into Neela Therapeutics, Inc., a newly formed independent company, prior to the closing of this acquisition.
Human Immunology Biosciences
On July 2, 2024, we completed the acquisition of all of the issued and outstanding shares of HI-Bio, a privately-held clinical-stage biotechnology company focused on targeted therapies for patients with severe immune-mediated diseases. HI-Bio's lead asset, felzartamab, an anti-CD38 antibody, is currently being evaluated for several indications, including three leading indications, AMR, PMN and IgAN. Felzartamab has received Breakthrough Therapy Designation and ODD from the FDA for development in the treatment of PMN and AMR. Subsequent to our acquisition, felzartamab received ODD in the E.U. in PMN, IgAN and solid organ transplantation. The acquisition of HI-Bio is expected to augment our pipeline and build on our expertise in immunology.
Under the terms of this acquisition, we paid shareholders of HI-Bio approximately $ 1.15  billion at closing and may pay up to a total of $ 650.0  million in contingent development and regulatory milestone payments. The $ 1.15  billion paid included approximately $ 74.5  million related to HI-Bio's outstanding, non-vested equity awards, inclusive of employer taxes, of which $ 56.4  million was recognized as share-based compensation payments to settle non-vested equity awards attributable to the post-acquisition service period and therefore not reflected as a component of total purchase price paid. Of the total $ 56.4  million, we recognized approximately $ 42.5  million as a charge to research and development expense with the remaining $ 13.9  million as a charge to selling, general and administrative expense within our consolidated statements of income for the year ended December 31, 2024 . These amounts were associated with the accelerated vesting of stock options and RSUs previously granted to HI-Bio employees and required no future services to vest.
Upon closing we also paid an additional $ 43.7  million related to working capital adjustments as of the transaction close date, which was included as a component of total purchase price paid.
We funded this acquisition through available cash on hand and accounted for this acquisition as a business combination using the acquisition method of accounting in accordance with ASC Topic 805, Business Combinations , and recorded assets acquired and liabilities assumed at their respective fair values as of the acquisition date.
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Purchase Price Consideration
Total consideration transferred for the acquisition of HI-Bio is summarized as follows:

(In millions) As of July 2, 2024

Cash consideration paid to HI-Bio shareholders (1)
$ 1,137.3  
Contingent consideration 485.1  

Total consideration $ 1,622.4  

(1) Represents total consideration paid to shareholders of HI-Bio of $ 1.15  billion, plus an additional $ 43.7  million related to working capital adjustments as of the transaction close date, less $ 56.4  million of cash paid for HI-Bio's outstanding, non-vested equity awards, inclusive of employer taxes, which were recognized as compensation attributable to the post-acquisition service period and therefore not reflected as a component of total consideration.
Contingent Consideration: We may make certain contingent payments to the former shareholders of HI-Bio upon the achievement of certain development and regulatory milestones. As of the acquisition date, the maximum aggregate amount payable for these potential milestones was $ 650.0 million. The acquisition-date fair value of these milestones was approximately $ 485.1 million and was estimated utilizing a probability-adjusted discounted cash flow calculation using an appropriate discount rate dependent on the nature and timing of the milestone payments, which ranged from 6.2 % to 7.0 %, and probabilities of technological and regulatory success ranging from 67.0 % to near-certain probability.
Of the total contingent consideration recorded as of the transaction close date, approximately $ 279.3 million related to milestones classified as short-term and reflected as a component of accrued expense and other with the remaining $ 205.8 million reflected as a component of other long-term liabilities within our consolidated balance sheets. The short-term liability related to the fourth patient dosed in a Phase 3 clinical trial of felzartamab in a first and s econd indication, which would each result in the achievement of a $ 150.0  million milestone payment.
Changes in the fair value of the contingent consideration obligation subsequent to the transaction close date are being recognized as (gain) loss on fair value remeasurement of contingent consideration within our consolidated statements of income. This fair value measurement is based on significant inputs that are not observable in the market and thus represent Level 3 fair value measurements. For additional information related to the fair value of this obligation, please read Note 8, Fair Value Measurements , to these consolidated financial statements.
Other Contractual Commitments: We acquired HI-Bio's pre-existing in-license commitments under third-party agreements with MorphoSys, which include tiered royalties on potential future sales ranging from high-single digit to mid-teen percentages, as well as potential future development, regulatory and commercial milestone payments of up to $ 130.0  million, $ 230.0  million and $ 640.0  million, respectively. At the transaction close date the achievement of these milestones was not considered probable and therefore not recorded in our financial statements.
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Purchase Price Allocation
We finalized purchase accounting for this acquisition in the second quarter of 2025.
The following table summarizes the amounts recognized for assets acquired and liabilities assumed as of the acquisition date, and reflects measurement period adjustments made to the amounts initially recorded as of the acquisition date on July 2, 2024. The related impact to our consolidated statements of income that would have been recognized in previous periods if the adjustments were recognized as of the acquisition date is immaterial.

(In millions) Amounts Recognized as of
Acquisition Date
(as adjusted)
Cash and cash equivalents $ 62.5  

Intangible assets:
IPR&D - felzartamab (IgAN) 920.0  
IPR&D - felzartamab (AMR)
450.0  
IPR&D - felzartamab (PMN) 265.0  
Other clinical programs 7.9  
Prepaid expense and other assets (1)
1.4  

Operating lease assets 1.2  
Accounts payable ( 1.1 )
Accrued liabilities ( 35.0 )
Deferred tax liability (1)
( 309.3 )
Operating lease liabilities ( 1.2 )

Total identifiable net assets 1,361.4  
Goodwill (1)
261.0  
Total assets acquired and liabilities assumed $ 1,622.4  

(1) Includes measurement period adjustments recorded in 2025 that increased prepaid expense and other assets by $ 0.4 million, net deferred tax liability by $ 4.9 million and goodwill by $ 4.5 million.
Intang ible assets: Intangible assets comprised of approximately $ 1.6  billion of IPR&D related to HI-Bio's lead asset felzartamab. This includes $ 920.0  million of IPR&D related to felzartamab indication for IgAN, $ 450.0  million of IPR&D related to felzartamab indication for AMR and $ 265.0  million of IPR&D related to felzartamab indication for PMN. The estimated fair values of the program related intangible assets were determined using a multi-period excess earnings method, a form of the income approach, utilizing cash flow analyses and a discount rate of 14.5 %. These fair value measurements were based on significant inputs that are not observable in the market and thus represent Level 3 fair value measurements.
Goodwill: Goodwill was calculated as the excess of the consideration transferred over the net assets recognized and represents the future economic benefits arising from the other assets acq uired that could not be individually identified and separately recognized. We recognized goodwill of approximately $ 261.0  million, which includes measurement period adjustments, and is not deductible for tax purposes. The goodwill recognized from our acquisition of HI-Bio is primarily the result of the deferred tax consequences from the transaction recorded for financial statement purposes.
Acquisition-related expense: Acquisition-related expense, primarily comprised of advisory and legal fees, and other transaction costs, totaled approximately $ 2.8  million and were recorded within selling, general and administrative expense within our consolidated statements of income for the year ended December 31, 2024.
Reata Pharmaceuticals, Inc.
On September 26, 2023, we completed the acquisition of all of the issued and outstanding shares of Reata, a biopharmaceutical company focused on developing therapeutics that regulate cellular metabolism and inflammation in serious neurologic diseases. As a result of this transaction we acquired SKYCLARYS (omaveloxolone), the first and only drug approved in the U.S., the E.U. and certain international markets for the treatment of FA in adults and adolescents aged 16 years and older, as well as other clinical and preclinical pipeline programs.
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Under the terms of this acquisition, we paid Reata shareholders $ 172.50 in cash for each issued and outstanding Reata share, which totaled approximately $ 6.6  billion. In addition, we agreed to pay approximately $ 983.9  million in cash for Reata's outstanding equity awards, inclusive of employer taxes, of which approximately $ 590.5  million was attributable to pre-acquisition services and is therefore reflected as a component of total purchase price paid. Of the $ 983.9  million paid to Reata's equity award holders, we recognized approximately $ 393.4  million as compensation attributable to the post-acquisition service period, of which $ 196.4  million was recognized as a charge to selling, general and administrative expense with the remaining $ 197.0  million as a charge to research and development expense within our consolidated statements of income for the year ended December 31, 2023. These amounts were associated with the accelerated vesting of stock options and RSUs previously granted to Reata employees that required no future services to vest.
We funded this acquisition through available cash, cash equivalents and marketable securities, supplemented by the issuance of a $ 1.0  billion term loan under our 2023 Term Loan. For additional information on our 2023 Term Loan, please read Note 13, Indebtedness , to these consolidated financial statements.
We accounted for this acquisition as a business combination using the acquisition method of accounting in accordance with ASC Topic 805, Business Combinations , and recorded assets acquired and liabilities assumed at their respective fair values as of the acquisition date.
Purchase Price Consideration
Total consideration transferred for the acquisition of Reata is summarized as follows:

(In millions) As of September 26, 2023
Cash consideration paid to Reata shareholders (1)
$ 6,602.9  
Fair value of Reata equity compensation pre-acquisition services and related taxes (2)
590.5  
Total consideration $ 7,193.4  

(1) Represents cash consideration transferred of $ 172.50 per outstanding Reata ordinary share based on 38.3  million Reata shares outstanding at closing.
(2) Represents the fair value of Reata stock options and stock units issued to Reata equity award holders and the related taxes attributable to pre-acquisition vesting services.
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Purchase Price Allocation
We finalized purchase accounting for this acquisition in the third quarter of 2024. The following table summarizes the amounts recognized for assets acquired and liabilities assumed as of the acquisition date, and reflects measurement period adjustments made to the amounts initially recorded as of the acquisition date on September 26, 2023. The measurement period adjustments summarized below resulted from updates to our valuation assumptions related to the estimated amounts and timing of future cash flows associated with certain intangible assets, updates of our assumptions related to the quantities, selling location and remaining manufacturing and selling costs of acquired inventory, and other assets and liabilities. The related impact to our consolidated statements of income that would have been recognized in previous periods if the adjustments were recognized as of the acquisition date is immaterial.

(In millions) Amounts Recognized as of Acquisition Date
(as adjusted)
Cash and cash equivalents $ 267.3  
Accounts receivable 15.9  
Inventory 1,259.0  
Other current assets (1)
54.6  
Intangible assets:
Completed technology for SKYCLARYS (U.S.) 4,200.0  
In-process research and development (omaveloxolone) 2,300.0  
Priority review voucher 100.0  
Other clinical programs 40.0  
Operating lease assets 121.2  
Accrued expense and other (1)
( 110.3 )
Debt payable ( 159.9 )
Contingent payable to Blackstone ( 300.0 )
Deferred tax liability (1)
( 909.3 )
Operating lease liabilities ( 151.8 )
Other assets and liabilities, net ( 2.5 )
Total identifiable net assets 6,724.2  
Goodwill (1)
469.2  
Total assets acquired and liabilities assumed $ 7,193.4  

(1) Includes measurement period adjustments recorded in 2024 that increased other current assets by $ 1.0  million, accrued expense and other by $ 8.8  million and goodwill by $ 4.7  million, and decreased deferred tax liability by $ 3.1  million.
Inventory: Total inventory acquired was approximately $ 1.3  billion, which reflects a step-up in the fair value of finished goods and work-in-process inventory for SKYCLARYS. The fair value was determined based on the estimated selling price of the inventory, less the remaining manufacturing and selling costs and a normal profit margin on those manufacturing and selling efforts. This fair value step-up adjustment is being amortized to cost of sales as the inventory is sold or research and development expense as the inventory is used for clinical purposes within our consolidated statements of income. We expect this amount to be fully amortized by the end of 2028.
Intang ible assets: Intangible assets are comprised of $ 4.2  billion related to SKYCLARYS commercialization rights in the U.S., $ 2.3  billion of IPR&D related to the omaveloxolone program outside the U.S., which had not yet received regulatory approval in the E.U. as of the acquisition date, $ 100.0  million related to a rare pediatric disease PRV which may be used to obtain priority review by the FDA for a future regulatory submission or sold to a third party and $ 40.0  million related to other clinical programs. The estimated fair values of the program related intangible assets were determined using a multi-period excess earnings method, a form of the income approach, utilizing a discount rate of 14.3 % and the estimated fair value of the PRV was based on recent external purchase and sale transactions of similar vouchers.
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NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

Our valuation of the SKYCLARYS commercialization rights reflects the assumption that, using an economic consumption model, the related $ 4.2  billion intangible asset will be amortized over its expected economic life. Upon SKYCLARYS receiving regulatory approval in the E.U. in February 2024, we began selling the product in certain countries in Europe, and began amortizing the $ 2.3  billion IPR&D asset related to the program outside the U.S. over its expected economic life using an economic consumption model.
These fair value measurements were based on significant inputs not observable in the market and thus represent Level 3 fair value measurements.
Leases: We assumed responsibility for a single-tenant, build-to-suit building of approximately 327,400 square feet of office and laboratory space located in Plano, Texas, with an initial lease term of 16 years. We recorded a lease liability of approximately $ 151.8  million, which represented the net present value of rental expense over the remaining lease term of approximately 15 years, with a corresponding right-of-use asset of approximately $ 121.2  million, which represented our estimate of the fair value for a market participant of the rental market in the Dallas, Texas area. Included in our estimate of the market rental rate was the value of any leasehold improvements or tenant allowances related to the building. We do not intend to occupy this building and are evaluating opportunities to sublease the property.
Goodwill: Goodwill was calculated as the excess of the consideration transferred over the net assets recognized and represents the future economic benefits arising from the other assets acquired that could not be individually identified and separately recognized. We recognized goodwill of approximately $ 469.2  million, which includes measurement period adjustments, and is not deductible for tax purposes. The goodwill recognized from our acquisition of Reata is primarily the result of the deferred tax consequences from the transaction recorded for financial statement purposes.
Acquisition-related expense: Acquisition-related expense, primarily comprised of regulatory, advisory and legal fees, and other transaction costs, totaled approximately $ 28.4  million and were recorded in selling, general and administrative expense within our consolidated statements of income for the year ended December 31, 2023.

Note 3:
Dispositions

Sale of Joint Venture Equity Interest in Samsung Bioepis
In April 2022 we completed the sale of our 49.9 % equity interest in Samsung Bioepis to Samsung BioLogics in exchange for total consideration of approximately $ 2.3  billion. Under the terms of this transaction, we received approximately $ 1.0  billion in cash at closing, with approximately $ 1.3  billion in cash to be deferred over two payments. The first deferred payment of $ 812.5  million was received in April 2023 and the second deferred payment of $ 437.5  million was received in April 2024.
For the year ended December 31, 2024, we recognized a gain of approximately $ 7.5 million to reflect the change in fair value associated with the passage of time related to the second deferred payment due to us, which was received in April 2024. For the year ended December 31, 2023, we recognized gains of approximately $ 13.7  million and $ 24.6  million to reflect the changes in fair value associated with changes in interest rates and the passage of time related to the first and second deferred payments due to us, respectively, which were received in April 2023 and April 2024, respectively. These changes were recorded in other (income) expense, net within our consolidated statements of income.
Sale of Priority Review Voucher
In April 2024 we completed the sale of our rare pediatric disease PRV, generated by the development associated with SPINRAZA, to a third party. In consideration for the PRV we received a cash payment of $ 103.0  million upon the closing of the PRV purchase, of which approximately $ 14.4  million was paid to Ionis. Our net portion of approximately $ 88.6  million was recognized in gain on sale of priority review voucher, net within our consolidated statements of income for the year ended December 31, 2024.
Sale of TOFIDENCE
In March 2025 we completed the sale of our regulatory and commercial rights in the U.S. for TOFIDENCE, a tocilizumab biosimilar referencing ACTEMRA, to Organon. Under the terms of this transaction, we received a payment
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NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

of approximately $ 51.0  million in July 2025 a nd recognized a de minimis loss within our consolidated statements of income for the year ended December 31, 2025.
Sale of BYOOVIZ and OPUVIZ Rights
In October 2025 we completed the sale of our remaining commercial rights to two ophthalmology assets in Europe: BYOOVIZ, a ranibizumab biosimilar referencing LUCENTIS, and OPUVIZ, an aflibercept biosimilar referencing EYLEA. Samsung Bioepis will have full responsibility for commercialization of BYOOVIZ upon the transfer of commercial rights from Biogen back to Samsung Bioepis, which became effective as of January 2026. Under the terms of this transaction, we received a payment of $ 28.0  million in November 2025 and recognized a minimal gain on disposal within our consolidated statements of income for the year ended December 31, 2025.
For additional information on our license arrangements with Samsung Bioepis, please read Note 19, Collaborative and Other Relationships , to these consolidated financial statements.

Note 4:
Restructuring

2023 Fit for Growth Restructuring Program
In 2023 we initiated cost saving measures as part of our Fit for Growth program to reduce operating costs, while improving operating efficiency and effectiveness. The Fit for Growth program generated approximately $ 1.0  billion in gross operating expense savings by the end of 2025, some of which has been reinvested in various initiatives. The Fit for Growth program included net headcount reductions of approximately 1,400 employees and we incurred total restructuring charges of approximately $ 320.0  million by the end of 2025.
Total charges incurred from our 2023 Fit for Growth program are summarized as follows:

For the Years Ended December 31,
2025 2024 2023
(In millions) Severance Costs Accelerated Depreciation and Other Total Severance Costs Accelerated Depreciation and Other Total Severance Costs Accelerated Depreciation and Other Total
Selling, general and administrative $ —   $ ( 1.4 ) $ ( 1.4 ) $ —   $ 13.8   $ 13.8   $ —   $ 23.3   $ 23.3  
Research and development —   10.1   10.1   —   11.7   11.7   —   1.2   1.2  
Restructuring charges 48.7   —   48.7   24.2   —   24.2   153.4   34.6   188.0  
Total charges $ 48.7   $ 8.7   $ 57.4   $ 24.2   $ 25.5   $ 49.7   $ 153.4   $ 59.1   $ 212.5  

Other Costs: Includes costs associated with items such as asset abandonment and write-offs, facility closure costs, pre-tax gains and losses resulting from the termination of certain leases, employee non-severance expense, consulting fees and other costs.
Reata Integration
Following the close of our Reata acquisition in September 2023, we implemented an integration plan designed to realize operating synergies through cost savings and avoidance. Under this initiative, we estimated we would incur total integration charges of approximately $ 35.0  million related to severance and employment costs, which were substantially incurred during 2023.
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NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

Total charges incurred from our Reata integration are summarized as follows:

For the Years Ended December 31,
2025 2024 2023
(In millions) Severance Costs Accelerated Depreciation and Other Total Severance Costs Accelerated Depreciation and Other Total Severance Costs Accelerated Depreciation and Other Total
Selling, general and administrative $ —   $ 6.8   $ 6.8   $ —   $ 6.3   $ 6.3   $ —   $ —   $ —  
Research and development —   14.3   14.3   —   11.9   11.9   —   —   —  
Restructuring charges ( 0.7 ) —   ( 0.7 ) 3.4   —   3.4   30.4   —   30.4  
Total charges $ ( 0.7 ) $ 21.1   $ 20.4   $ 3.4   $ 18.2   $ 21.6   $ 30.4   $ —   $ 30.4  

In connection with our acquisition of Reata we assumed responsibility for a single-tenant, build-to-suit building of approximately 327,400 square feet of office and laboratory space located in Plano, Texas, with an initial lease term of 16 years. We do not intend to occupy this building and are evaluating opportunities to sublease the property. For additional information on our acquisition of Reata, please read Note 2, Acquisitions , to these consolidated financial statements.
Restructuring Reserve
Charges and spending related to workforce reductions are summarized as follows:

(In millions) Workforce Reductions
Restructuring reserve, December 31, 2023
$ 75.4  
Expense 30.2  
Payment ( 73.8 )
Foreign currency and other adjustments 0.1  
Restructuring reserve, December 31, 2024
31.9  
Expense 48.6  
Payment ( 61.5 )
Foreign currency and other adjustments ( 3.2 )
Restructuring reserve, December 31, 2025
$ 15.8  

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NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

Note 5:
Revenue

Product Revenue
Revenue by product are summarized as follows:

  For the Years Ended December 31,
  2025 2024 2023
(In millions) United
States Rest of
World Total United
States Rest of
World Total United
States Rest of
World Total
Multiple Sclerosis:
TECFIDERA $ 168.5   $ 511.2   $ 679.7   $ 169.2   $ 797.9   $ 967.1   $ 263.1   $ 749.4   $ 1,012.5  
VUMERITY 651.2   95.6   746.8   538.6   89.4   628.0   512.1   64.2   576.3  
Total Fumarate 819.7   606.8   1,426.5   707.8   887.3   1,595.1   775.2   813.6   1,588.8  
AVONEX 482.9   212.6   695.5   451.3   256.2   707.5   536.7   274.3   811.0  
PLEGRIDY 104.9   145.2   250.1   111.4   149.1   260.5   126.2   168.5   294.7  
Total Interferon 587.8   357.8   945.6   562.7   405.3   968.0   662.9   442.8   1,105.7  
TYSABRI 965.0   700.4   1,665.4   920.0   795.0   1,715.0   997.9   879.0   1,876.9  
FAMPYRA (1)
—   1.4   1.4   —   71.7   71.7   —   90.5   90.5  
Subtotal: Multiple Sclerosis 2,372.5   1,666.4   4,038.9   2,190.5   2,159.3   4,349.8   2,436.0   2,225.9   4,661.9  

Rare Disease:
SPINRAZA 625.5   921.3   1,546.8   625.7   947.5   1,573.2   610.5   1,130.7   1,741.2  
SKYCLARYS (2)
310.6   209.9   520.5   301.1   81.4   382.5   55.9   —   55.9  
QALSODY (3)
30.1   56.8   86.9   20.9   11.5   32.4   5.8   0.1   5.9  
Subtotal: Rare Disease 966.2   1,188.0   2,154.2   947.7   1,040.4   1,988.1   672.2   1,130.8   1,803.0  

Biosimilars:
BENEPALI —   453.2   453.2   —   479.1   479.1   —   438.8   438.8  
IMRALDI —   190.2   190.2   —   213.1   213.1   —   222.1   222.1  
FLIXABI —   52.6   52.6   —   63.2   63.2   —   77.4   77.4  
BYOOVIZ 13.0   19.4   32.4   23.0   13.6   36.6   29.2   2.5   31.7  
TOFIDENCE 0.7   —   0.7   1.1   —   1.1   —   —   —  
Subtotal: Biosimilars 13.7   715.4   729.1   24.1   769.0   793.1   29.2   740.8   770.0  

Other:
ZURZUVAE 195.1   —   195.1   72.2   —   72.2   1.6   —   1.6  
Other (4)
0.4   1.7   2.1   2.8   7.5   10.3   2.4   7.8   10.2  
Subtotal: Other 195.5   1.7   197.2   75.0   7.5   82.5   4.0   7.8   11.8  
Total product revenue, net $ 3,547.9   $ 3,571.5   $ 7,119.4   $ 3,237.3   $ 3,976.2   $ 7,213.5   $ 3,141.4   $ 4,105.3   $ 7,246.7  

(1) Effective January 1, 2025, our collaboration and license agreement for FAMPYRA global commercialization rights was terminated.
(2) SKYCLARYS became commercially available in the E.U. during the first quarter of 2024.
(3) QALSODY became commercially available in the E.U. during the second quarter of 2024.
(4) Other includes FUMADERM and ADUHELM.
We recognized revenue from two wholesalers accounting for 28.0 % and 15.8 % of gross product revenue in 2025, 25.9 % and 13.4 % of gross product revenue in 2024 and 27.0 % and 9.9 % of gross product revenue in 2023, respectively.
As of December 31, 2025, two wholesale distributors individually accounted for approximately 25.4 % and 15.2 % of net accounts receivable associated with our product sales, as compared to 27.2 % and 11.7 % as of December 31, 2024, respectively.
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NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

An analysis of the change in reserves for discounts and allowances is summarized as follows:

As of December 31, 2025
(In millions) Discounts Contractual
Adjustments Returns Total
Balance, December 31, 2024 $ 162.7   $ 880.8   $ 48.1   $ 1,091.6  
Current provisions relating to sales in current year 832.4   2,773.1   31.9   3,637.4  
Adjustments relating to prior years 2.2   ( 83.4 ) 0.7   ( 80.5 )
Payments/credits relating to sales in current year ( 728.3 ) ( 1,905.8 ) ( 1.7 ) ( 2,635.8 )
Payments/credits relating to sales in prior years ( 153.3 ) ( 618.6 ) ( 30.0 ) ( 801.9 )
Balance, December 31, 2025 $ 115.7   $ 1,046.1   $ 49.0   $ 1,210.8  

As of December 31, 2024
(In millions) Discounts Contractual
Adjustments Returns Total
Balance, December 31, 2023 $ 173.3   $ 857.1   $ 31.6   $ 1,062.0  
Current provisions relating to sales in current year 824.2   2,687.5   23.6   3,535.3  
Adjustments relating to prior years 8.0   ( 38.7 ) 14.2   ( 16.5 )
Payments/credits relating to sales in current year ( 670.9 ) ( 1,989.7 ) ( 0.6 ) ( 2,661.2 )
Payments/credits relating to sales in prior years ( 171.9 ) ( 635.4 ) ( 20.7 ) ( 828.0 )
Balance, December 31, 2024 $ 162.7   $ 880.8   $ 48.1   $ 1,091.6  

As of December 31, 2023
(In millions) Discounts Contractual
Adjustments Returns Total
Balance, December 31, 2022 $ 153.8   $ 857.7   $ 23.5   $ 1,035.0  
Current provisions relating to sales in current year 735.6   2,720.1   19.0   3,474.7  
Adjustments relating to prior years ( 0.4 ) ( 38.4 ) 19.2   ( 19.6 )
Payments/credits relating to sales in current year ( 572.9 ) ( 1,944.8 ) ( 2.1 ) ( 2,519.8 )
Payments/credits relating to sales in prior years ( 142.8 ) ( 737.5 ) ( 28.0 ) ( 908.3 )
Balance, December 31, 2023 $ 173.3   $ 857.1   $ 31.6   $ 1,062.0  

The total reserves above, which are included in our consolidated balance sheets, are summarized as follows:

  As of December 31,
(In millions) 2025 2024
Reduction of accounts receivable $ 210.4   $ 154.1  
Component of accrued expense and other 1,000.4   937.5  
Total revenue-related reserves $ 1,210.8   $ 1,091.6  

Revenue from Anti-CD20 Therapeutic Programs
Revenue from anti-CD20 therapeutic programs is summarized in the table below. For purposes of this footnote, we refer to RITUXAN and RITUXAN HYCELA collectively as RITUXAN.

  For the Years Ended December 31,
(In millions) 2025 2024 2023
Royalty revenue on sales of OCREVUS $ 1,414.9   $ 1,339.5   $ 1,266.2  
Biogen's share of pre-tax profits in the U.S. for RITUXAN, GAZYVA and LUNSUMIO 420.2   392.0   409.4  
Other revenue from anti-CD20 therapeutic programs 25.5   18.4   14.0  
Total revenue from anti-CD20 therapeutic programs $ 1,860.6   $ 1,749.9   $ 1,689.6  

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NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

Approximately 18.8 %, 18.1 % and 17.2 % of our total revenue in 2025, 2024 and 2023, respectively, was derived from our collaboration arrangements with Genentech. For additional information on our collaboration arrangements with Genentech, please read Note 19, Collaborative and Other Relationships , to these consolidated financial statements.
Alzheimer's Collaboration Revenue
Alzheimer's collaboration revenue consists of our 50.0 % share of LEQEMBI product revenue, net and cost of sales, including royalties, as we are not the principal. We began recognizing Alzheimer's collaboration revenue upon the accelerated approval of LEQEMBI in the U.S. during the first quarter of 2023.
For the years ended December 31, 2025 and 2024, we recognized Alzheimer's collaboration revenue of approximately $ 177.7 million and $ 59.9 million, respectively, within our consolidated statements of income. For the year ended December 31, 2023, our share of LEQEMBI product revenue, net, was fully offset by our share of cost of sales, including royalties, resulting in a zero net impact to Alzheimer's collaboration revenue within our consolidated statements of income.
For additional information on our collaboration arrangements with Eisai, please read Note 19, Collaborative and Other Relationships , to these consolidated financial statements.
Contract Manufacturing, Royalty and Other Revenue
Contract manufacturing, royalty and other revenue is summarized as follows:

  For the Years Ended December 31,
(In millions) 2025 2024 2023

Contract manufacturing revenue $ 679.4   $ 592.1   $ 848.2  
Royalty and other revenue 53.5   60.5   51.1  
Total contract manufacturing, royalty and other revenue $ 732.9   $ 652.6   $ 899.3  

Contract Manufacturing Revenue
Contract manufacturing revenue primarily reflects amounts earned under contract manufacturing agreements with our strategic customers and batches of LEQEMBI related to our collaboration with Eisai.
Royalty and Other Revenue
Royalty and other revenue primarily reflects royalty revenue on biosimilar products from our license arrangements with Samsung Bioepis and royalties we receive from net sales on products related to patents that we have out-licensed.
For additional information on our license arrangements with Samsung Bioepis and our collaboration arrangements with Eisai, please read Note 19, Collaborative and Other Relationships , to these consolidated financial statements.
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Note 6:
Inventory

The components of inventory are summarized as follows:

  As of December 31,
(In millions) 2025 2024
Raw materials $ 293.4   $ 317.8  
Work in process 1,595.2   1,882.8  
Finished goods 424.9   353.8  
Total inventory $ 2,313.5   $ 2,554.4  

Balance Sheet Classification:
Inventory $ 2,168.1   $ 2,460.5  
Investments and other assets 145.4   93.9  
Total inventory $ 2,313.5   $ 2,554.4  

Long-term inventory is included in investments and other assets within our consolidated balance sheets.
As a result of our acquisition of Reata in September 2023 we recorded a fair value step-up adjustment related to the acquired inventory of SKYCLARYS of approximately $ 1.3  billion. This fair value step-up adjustment is being amortized to cost of sales as the inventory is sold or research and development expense as the inventory is used for clinical purposes within our consolidated statements of income. We expect this amount to be fully amortized by the end of 2028. For the years ended December 31, 2025, 2024 and 2023, amortization from the fair value step-up adjustment was approximately $ 240.8 million, $ 230.0 million and $ 31.5 million, respectively. For the years ended December 31, 2025 and 2024, amortization from the fair value step-up adjustment includes approximately $ 23.9 million and $ 48.5 million, respectively, of inventory used for clinical purposes, which is reflected in research and development expense within our consolidated statements of income. For additional information on our acquisition of Reata, please read Note 2, Acquisitions , to these consolidated financial statements.
Write Downs and Other Charges
Inventory amounts written down as a result of excess, obsolescence or unmarketability are charged to cost of sales, and totaled $ 29.2 million, $ 101.9 million and $ 124.4 million for the years ended December 31, 2025, 2024 and 2023, respectively.

Note 7:
Intangible Assets and Goodwill

Intangible Assets
Intangible assets, net of accumulated amortization, impairment charges and adjustments are summarized as follows:

    As of December 31, 2025 As of December 31, 2024
(In millions) Estimated Life Cost Accumulated
Amortization Net Cost Accumulated
Amortization Net

Completed technology 1 - 30 years
$ 14,067.3   $ ( 6,687.8 ) $ 7,379.5   $ 14,138.4   $ ( 6,254.1 ) $ 7,884.3  
In-process research and development Indefinite until commercialization 1,635.0   —  1,635.0   1,642.9   —  1,642.9  
Priority review voucher Indefinite 100.0   —  100.0   100.0   —  100.0  
Trademarks and trade names Indefinite 64.0   —  64.0   64.0   —  64.0  
Total intangible assets $ 15,866.3   $ ( 6,687.8 ) $ 9,178.5   $ 15,945.3   $ ( 6,254.1 ) $ 9,691.2  

Amortization and Impairments
Amortization and impairment of acquired intangible assets totaled $ 515.0 million, $ 446.7 million and $ 240.6 million for the years ended December 31, 2025, 2024 and 2023, respectively.
Amortization of acquired intangible assets, excluding impairment charges, totaled $ 507.1 million, $ 386.5 million and $ 240.6 million for the years ended December 31, 2025, 2024 and 2023, respectively. The increase in
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amortization of acquired intangible assets, excluding impairment charges, was primarily due to amortization for the acquired intangible assets associated with SKYCLARYS and TYSABRI.
For the year ended December 31, 2025, amortization and impairment of acquired intangible assets reflects the impact of $ 7.9  million in impairment charges related to compounds acquired from HI-Bio.
For the year ended December 31, 2024, amortization and impairment of acquired intangible assets reflects the impact of a $ 40.0  million impairment charge related to intangible assets from other clinical programs we acquired from Reata, reducing the remaining book value of these IPR&D intangible assets to zero , and a $ 20.2  million impairment charge related to intangible assets associated with the termination of Samsung Bioepis' commercialization rights during the third quarter of 2024. For the year ended December 31, 2023, we had no impairment charges.
We monitor events and expectations regarding product performance. If new information indicates that the assumptions underlying our most recent analysis are substantially different than those utilized in our current estimates, our analysis would be updated and may result in a significant change in the anticipated lifetime revenue of the relevant products. The occurrence of an adverse event could substantially increase the amount of amortization expense related to our acquired intangible assets as compared to previous periods or our current expectations, which may result in a significant negative impact on our future results of operations.
Completed Technology
Completed technology primarily relates to our other marketed products and programs acquired through asset acquisitions, licenses and business combinations. Completed technology intangible assets are amortized over their estimated useful lives, which range between approximately 1 to 30 years, with a remaining weighted average useful life of 12 years, as of December 31, 2025.
IPR&D Related to Business Combinations
IPR&D represents the fair value assigned to research and development assets that we acquired as part of a business combination and had not yet reached technological feasibility at the date of acquisition. We review amounts capitalized as acquired IPR&D for impairment annually, as of October 31, and whenever events or changes in circumstances indicate to us that the carrying value of the assets might not be recoverable.
The carrying value associated with our IPR&D assets as of December 31, 2025 and 2024, primarily relates to the IPR&D programs we acquired in connection with our acquisition of HI-Bio in July 2024, with an estimated fair value of approximately $ 1.6  billion.
Priority Review Voucher
In connection with our acquisition of Reata in September 2023 we acquired a rare pediatric disease PRV which may be used to obtain priority review by the FDA for a future regulatory submission or sold to a third party . We recorded the PRV based on its estimated fair value of $ 100.0  million as an intangible asset.
For additional information on our acquisitions of Reata and HI-Bio, please read Note 2, Acquisitions , to these consolidated financial statements.
Estimated Future Amortization of Intangible Assets
The estimated future amortization of finite-lived intangible assets for the next five years is expected to be as follows:

(In millions) As of December 31, 2025
2026 $ 485.0  
2027 485.0  
2028 525.0  
2029 575.0  
2030 645.0  

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Goodwill
The following table provides a roll forward of the changes in our goodwill balance:

  As of December 31,
(In millions) 2025 2024
Goodwill, January 1 $ 6,478.9   $ 6,219.2  
Goodwill resulting from HI-Bio acquisition (1)
4.5   256.5  
Goodwill resulting from Reata acquisition (2)
—   4.7  

Other (3)
7.7   ( 1.5 )
Goodwill, December 31 $ 6,491.1   $ 6,478.9  

(1) Goodwill resulting from the HI-Bio acquisition for the year ended December 31, 2025, relates to HI-Bio measurement period adjustments recognized during 2025.
(2) Goodwill resulting from the Reata acquisition for the year ended December 31, 2024, relates to Reata measurement period adjustments recognized during 2024.
(3) Other includes adjustments related to foreign currency exchange rate fluctuations.
For additional information on our acquisitions of Reata and HI-Bio, please read Note 2, Acquisitions , to these consolidated financial statements.
As of December 31, 2025 and 2024, we had no accumulated impairment losses related to goodwill.
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BIOGEN INC. AND SUBSIDIARIES
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

Note 8:
Fair Value Measurements

The tables below present information about our assets and liabilities that are regularly measured and carried at fair value and indicate the level within the fair value hierarchy of the valuation techniques we utilized to determine such fair value:

Fair Value Measurements on a Recurring Basis
As of December 31, 2025
(In millions) Total Quoted Prices
in Active
Markets
(Level 1) Significant
Other Observable
Inputs
(Level 2) Significant
Unobservable
Inputs
(Level 3)
Assets:
Cash equivalents $ 2,233.2   $ —   $ 2,233.2   $ —  
Marketable debt securities:
Corporate debt securities 537.6   —   537.6   —  
Government securities 648.8   —   648.8   —  
Mortgage and other asset backed securities 52.7   —   52.7   —  
Marketable equity securities 118.1   118.1   —   —  
Other current assets:

Derivative contracts 10.0   —   10.0   —  
Other non-current assets:
Convertible notes (1)
35.0   —   —   35.0  
Plan assets for deferred compensation 52.2   —   52.2   —  
Derivative contracts 0.4   —   0.4   —  
Total $ 3,688.0   $ 118.1   $ 3,534.9   $ 35.0  
Liabilities:
Other current liabilities:
Derivative contracts $ 56.7   $ —   $ 56.7   $ —  

Other non-current liabilities:
Derivative contracts 2.2   —   2.2   —  
Contingent consideration obligations 246.4   —   —   246.4  
Total $ 305.3   $ —   $ 58.9   $ 246.4  

(1) Convertible notes includes a $ 30.0 million convertible note we invested in as part of our strategic research arrangement with City Therapeutics during 2025, as well as a $ 5.0  million convertible note we invested into Neela Therapeutics, Inc. during 2025. We elected the fair value option for both convertible notes. For additional information on the arrangement with City Therapeutics, please read Note 19, Collaborative and Other Relationships , to these consolidated financial statements.
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BIOGEN INC. AND SUBSIDIARIES
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

Fair Value Measurements on a Recurring Basis
As of December 31, 2024
(In millions) Total Quoted Prices
in Active
Markets
(Level 1) Significant
Other Observable
Inputs
(Level 2) Significant
Unobservable
Inputs
(Level 3)
Assets:
Cash equivalents $ 1,664.9   $ —   $ 1,664.9   $ —  

Marketable equity securities 179.7   179.7   —   —  
Other current assets:
Derivative contracts 62.5   —   62.5   —  
Other non-current assets:

Plan assets for deferred compensation 42.8   —   42.8   —  
Total $ 1,949.9   $ 179.7   $ 1,770.2   $ —  
Liabilities:
Other current liabilities:
Derivative contracts $ 11.7   $ —   $ 11.7   $ —  
Contingent consideration obligations 291.2   —   —   291.2  
Other non-current liabilities:

Contingent consideration obligations 221.6   —   —   221.6  
Total $ 524.5   $ —   $ 11.7   $ 512.8  

Our marketable equity securities represent investments in publicly traded equity securities. Our ability to liquidate our investments in Denali may be limited by the size of our interest, the volume of market-related activity, our concentrated level of ownership and potential restrictions resulting from our status as a collaborator. Therefore, we may realize significantly less than the current value of such investments. For additional information on our investments in Denali common stock, please read Note 9, Financial Instruments , and Note 18, Other Consolidated Financial Statement Detail , to these consolidated financial statements.
There have been no material impairments of our assets measured and carried at fair value as of December 31, 2025 and 2024. In addition, there have been no changes to our valuation techniques as of December 31, 2025 and 2024.
For a description of our validation procedures related to prices provided by third-party pricing services and our option pricing valuation model, please read Note 1, Summary of Significant Accounting Policies - Fair Value Measurements, to these consolidated financial statements.
Level 3 Assets and Liabilities Held at Fair Value
The following tables present quantitative information, as of the dates indicated, about the valuation techniques and significant unobservable inputs used in the valuation of our Level 3 financial assets and liabilities measured at fair value on a recurring basis:

Quantitative Information about Level 3 Fair Value Measurements
As of December 31, 2025
(In millions) Fair Value Valuation Technique Significant
Unobservable Input(s) Range Weighted
Average
Liabilities:
Contingent consideration obligations $ 246.4   Discounted cash flow Discount rate 5.3 % - 5.4 %
5.4 %

Expected timing of achievement of development milestones 2028 - 2030
—

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BIOGEN INC. AND SUBSIDIARIES
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

Quantitative Information about Level 3 Fair Value Measurements
As of December 31, 2024
(In millions) Fair Value Valuation Technique Significant
Unobservable Input(s) Range Weighted
Average
Liabilities:
Contingent consideration obligations $ 512.8   Discounted cash flow Discount rate 6.2 % - 6.3 %
6.2 %

Expected timing of achievement of development milestones 2025 - 2030
—

The weighted average discount rates were calculated based on the relative fair values of each distinct contingent consideration obligation related to our acquisition of HI-Bio in July 2024. In addition, we apply various probabilities of technological and regulatory success to the valuation models to estimate the fair values of these contingent consideration obligations, which ranged from approximate ly 70.0 % to 95.0 % as of December 31, 2025.
There were no transfers of assets or liabilities into or out of Level 3 as of December 31, 2025 and 2024.
Contingent Consideration Obligations
In connection with our acquisition of HI-Bio in July 2024 we agreed to make additional payments based upon the achievement of certain milestone events. The following table provides a roll forward of the fair value of our contingent consideration obligations, which were classified as Level 3 measurements:

  As of December 31,
(In millions) 2025 2024
Fair value, beginning of year $ 512.8   $ —  
Contingent consideration resulting from HI-Bio acquisition —   485.1  
Changes in fair value 33.6   27.7  
Payments ( 300.0 ) —  
Fair value, end of year $ 246.4   $ 512.8  

Changes in the fair values of our contingent consideration obligations, other than changes due to payments, are recognized as a (gain) loss on fair value remeasurement of contingent consideration within our consolidated statements of income. The fair values of the contingent consideration liabilities were based on a probability-adjusted discounted cash flow calculation using Level 3 fair value measurements and inputs. For additional information on the valuation techniques and inputs utilized in the valuation of our financial assets and liabilities, please read Note 1, Summary of Significant Accounting Policies, to these consolidated financial statements.
As of December 31, 2025, the total remaining fair value of our contingent consideration obligations of $ 246.4  million was classified as long-term and reflected as a component of other long-term liabilities within our consolidated balance sheets.
As of December 31, 2024, approximately $ 291.2  million of the fair value of our total contingent consideration obligations was classified as short-term and reflected as a component of accrued expense and other with the remaining $ 221.6  million reflected as a component of other long-term liabilities within our consolidated balance sheets.
For the year ended December 31, 2025, changes in the fair value of our contingent consideration obligations were primarily due to changes in interest rates used to revalue our contingent consideration liabilities and the passage of time. For the year ended December 31, 2024, changes in the fair value of our contingent consideration obligations were primarily due to changes in interest rates used to revalue our contingent consideration liabilities, the passage of time and updates to the expected timing of achieving certain milestones which will trigger contingent consideration payments.
During the second quarter of 2025 the first milestone related to the fourth patient dosed in a Phase 3 clinical trial of felzartamab for AMR was achieved, resulting in a $ 150.0 million milestone payment made to the former shareholders of HI-Bio, which was paid during the third quarter of 2025. In October 2025 the second milestone related to the fourth patient dosed in a Phase 3 clinical trial of felzartamab for IgAN was achieved, resulting in a
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BIOGEN INC. AND SUBSIDIARIES
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

$ 150.0 million milestone payment made to the former shareholders of HI-Bio, which was paid during the fourth quarter of 2025.
Financial Instruments Not Carried at Fair Value
Other Financial Instruments
Due to the short-term nature of certain financial instruments, the carrying value reflected in our consolidated balance sheets for current accounts receivable, due from anti-CD20 therapeutic programs, other current assets, accounts payable and accrued expense and other, approximates fair value.
Debt Instruments
The fair values of our debt instruments, which are Level 2 liabilities, are summarized as follows:

  Fair Value
As of December 31,
(In millions) 2025 2024
Current portion:
4.050 % Senior Notes due September 15, 2025 (1)
$ —   $ 1,741.0  
Current portion of notes payable —   1,741.0  

Non-current portion:
2.250 % Senior Notes due May 1, 2030
1,378.7   1,295.6  
5.050 % Senior Notes due January 15, 2031 (1)
413.0   —  
5.750 % Senior Notes due May 15, 2035 (1)
684.5   —  
5.200 % Senior Notes due September 15, 2045
1,029.5   1,008.0  
3.150 % Senior Notes due May 1, 2050
973.0   943.7  
3.250 % Senior Notes due February 15, 2051
461.8   448.9  
6.450 % Senior Notes due May 15, 2055 (1)
737.6   —  
Non-current portion of notes payable 5,678.1   3,696.2  
Total notes payable $ 5,678.1   $ 5,437.2  

(1) In May 2025 we issued our 2025 Senior Notes for an aggregate principal amount of $ 1.75  billion. In June 2025 we used the net proceeds from the sale of our 2025 Senior Notes to redeem in full our 4.050 % Senior Notes due September 15, 2025, prior to maturity. For additional information, please read Note 13, Indebtedness , to these consolidated financial statements.
The fair values of each of our series of Senior Notes were determined through market, observable and corroborated sources. The changes in the fair values of our Senior Notes as of December 31, 2025, compared to 2024, are primarily related to decreases in credit spreads used to value our Senior Notes since December 31, 2024. For additional information related to our Senior Notes, please read Note 13, Indebtedness , to these consolidated financial statements.

Note 9:
Financial Instruments

The following table summarizes our financial assets with maturities of less than 90 days from the date of purchase included in cash and cash equivalents in our consolidated balance sheets:

  As of December 31,
(In millions) 2025 2024
Money market funds $ 2,027.7   $ 1,664.9  
Overnight reverse repurchase agreements 70.0   —  
Short-term debt securities 15.4   —  
Commercial paper 120.1   —  
Total $ 2,233.2   $ 1,664.9  

The carrying value of our money market funds, overnight reverse repurchase agreements, short-term debt securities and commercial paper, including accrued interest, approximates fair value due to their short-term maturities.
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BIOGEN INC. AND SUBSIDIARIES
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

Our marketable equity securities gains (losses) are recorded in other (income) expense, net in our consolidated statements of income. The following tables summarize our marketable debt and equity securities, classified as available-for-sale:

As of December 31, 2025
(In millions) Amortized
Cost Gross
Unrealized
Gains Gross
Unrealized
Losses Fair
Value
Marketable debt securities:
Corporate debt securities:
Current $ 246.8   $ —   $ —   $ 246.8  
Non-current 290.6   0.2   —   290.8  
Government securities:
Current 560.4   —   —   560.4  
Non-current 88.4   —   —   88.4  
Mortgage and other asset backed securities:

Non-current 52.7   —   —   52.7  
Total marketable debt securities $ 1,238.9   $ 0.2   $ —   $ 1,239.1  

Marketable equity securities:

Marketable equity securities, non-current $ 227.7   $ —   $ ( 109.6 ) $ 118.1  
Total marketable equity securities $ 227.7   $ —   $ ( 109.6 ) $ 118.1  

As of December 31, 2024
(In millions) Amortized
Cost Gross
Unrealized
Gains Gross
Unrealized
Losses Fair
Value

Marketable equity securities:

Marketable equity securities, non-current $ 668.7   $ —   $ ( 489.0 ) $ 179.7  
Total marketable equity securities $ 668.7   $ —   $ ( 489.0 ) $ 179.7  

Summary of Contractual Maturities: Available-for-Sale Debt Securities
The estimated fair value and amortized cost of our marketable debt securities classified as available-for-sale by contractual maturity are summarized as follows:

As of December 31, 2025
(In millions) Estimated
Fair Value Amortized
Cost
Due in one year or less $ 807.2   $ 807.2  
Due after one year through five years 419.5   419.3  
Due after five years 12.4   12.4  
Total marketable debt securities $ 1,239.1   $ 1,238.9  

The average maturity of our marketable debt securities classified as available-for-sale as of December 31, 2025, was approximately 5 months.
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BIOGEN INC. AND SUBSIDIARIES
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

Proceeds from Marketable Debt Securities
The proceeds from maturities and sales of marketable debt securities and resulting realized gains and losses are summarized as follows:

  For the Years Ended December 31,
(In millions) 2025 2024 2023
Proceeds from maturities and sales $ 23.0   $ —   $ 7,380.8  
Realized gains —   —   1.4  
Realized losses —   —   18.4  

Realized losses for the year ended December 31, 2023, primarily relate to sales of U.S. treasuries and corporate bonds.
Strategic Investments
Our strategic investment portfolio includes investments in equity securities of certain biotechnology companies, which are reflected within our disclosures included in Note 8, Fair Value Measurements , to these consolidated financial statements, as well as venture capital funds where the underlying investments are in equity securities of certain biotechnology companies and non-marketable equity securities.
As of December 31, 2025 and 2024, our strategic investment portfolio was comprised of investments totaling $ 186.6 million and $ 226.7 million, respectively, which are included in investments and other assets within our consolidated balance sheets.
The decrease in our strategic investment portfolio as of December 31, 2025, compared to 2024, was primarily due to the decrease in the fair value of our investment in Denali common stock as well as the sale of our remaining investment in Sage common stock during the third quarter of 2025.
For additional information on our investments in Denali and Sage common stock, please read Note 8, Fair Value Measurements , and Note 18, Other Consolidated Financial Statement Detail , to these consolidated financial statements.

Note 10:
Derivative Instruments

Foreign Currency Forward Contracts - Hedging Instruments
Due to the global nature of our operations, portions of our revenue and operating expense are recorded in currencies other than the U.S. dollar. The value of revenue and operating expense measured in U.S. dollars is therefore subject to changes in foreign currency exchange rates. We enter into foreign currency forward contracts and foreign currency options with financial institutions with the primary objective to mitigate the impact of foreign currency exchange rate fluctuations on our international revenue and operating expense.
Foreign currency forward contracts and foreign currency options in effect as of December 31, 2025 and 2024, had durations of 1 to 21 months and 1 to 12 months, respectively. These contracts have been designated as cash flow hedges and unrealized gains and losses on the portion of these foreign currency forward contracts and foreign currency options that are included in the effectiveness test are reported in AOCI. Realized gains and losses of such contracts and options are recognized in revenue when the sale of product in the currency being hedged is recognized and in operating expense when the expense in the currency being hedged is recorded. We recognize all cash flow hedge reclassifications from AOCI and fair value changes of excluded portions in the same line item in our consolidated statements of income that have been impacted by the hedged item.
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BIOGEN INC. AND SUBSIDIARIES
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

The notional amount of foreign currency forward contracts and foreign currency options that were entered into to hedge forecasted revenue and operating expense is summarized as follows:

  Notional Amount
As of December 31,
(In millions) 2025 2024
Euro $ 1,531.0   $ 1,062.6  

British pound —   133.8  
Canadian dollar —   38.6  
Total foreign currency forward contracts and options $ 1,531.0   $ 1,235.0  

The pre-tax portion of the fair value of these foreign currency forward contracts and foreign currency options that were included in AOCI in total equity is summarized as follows:

For the Years Ended December 31,
(In millions) 2025 2024 2023
Unrealized gains $ —   $ 50.6   $ —  
Unrealized (losses) ( 73.3 ) ( 0.3 ) ( 34.8 )
Net unrealized gains (losses) $ ( 73.3 ) $ 50.3   $ ( 34.8 )

We expect the net unrealized losses of approximately $ 73.3 million to be settled over the next 15 months, of which approximately $ 68.5 million of these net unrealized losses are expected to be settled over the next 12 months, with any amounts in AOCI to be reported as an adjustment to revenue or operating expense. We consider the impact of our and our counterparties’ credit risk on the fair value of the contracts as well as the ability of each party to execute its contractual obligations. As of December 31, 2025 and 2024, credit risk did not materially change the fair value of our foreign currency forward contracts and forward currency options.
The following table summarizes the effect of foreign currency forward contracts and forward currency options designated as hedging instruments in our consolidated statements of income:

For the Years Ended December 31,
Net Gains/(Losses)
Reclassified from AOCI into Operating Income (in millions)
Net Gains/(Losses) Excluded from Effectiveness Testing and
Recognized in Operating Income (in millions)
Location 2025 2024 2023 Location 2025 2024 2023
Revenue $ ( 72.4 ) $ 18.1   $ 11.6   Revenue $ 9.7   $ ( 0.8 ) $ ( 2.4 )
Operating expense 21.3   ( 12.9 ) 3.7   Operating expense —   —   —  

Foreign Currency Forward Contracts - Other Derivative Instruments
We also enter into other foreign currency forward contracts, usually with durations of one month or less, to mitigate the foreign currency risk related to certain balance sheet positions. We have not elected hedge accounting for these transactions.
The aggregate notional amount of these outstanding foreign currency forward contracts was $ 1,193.7 million and $ 738.7 million as of December 31, 2025 and 2024, respectively. Net gains of $ 33.5 million, net losses of $ 49.7 million and net gains of $ 3.8 million related to these contracts were recorded as a component of other (income) expense, net for the years ended December 31, 2025, 2024 and 2023, respectively.
Summary of Derivative Instruments
While certain of our derivative instruments are subject to netting arrangements with our counterparties, we do not offset derivative assets and liabilities in our consolidated balance sheets. The amounts in the table below would not be substantially different if the derivative assets and liabilities were offset.
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BIOGEN INC. AND SUBSIDIARIES
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

The following table summarizes the fair value and presentation in our consolidated balance sheets of our outstanding derivative instruments, including those designated as hedging instruments:

As of December 31,
(In millions) Balance Sheet Location 2025 2024
Cash Flow Hedging Instruments:
Asset derivative instruments Other current assets $ 0.1   $ 58.4  
Investments and other assets 0.4   —  
Liability derivative instruments Accrued expense and other 54.0   0.3  
Other long-term liabilities 2.2   —  

Other Derivative Instruments:
Asset derivative instruments Other current assets 9.9   4.1  
Liability derivative instruments Accrued expense and other 2.7   11.4  

Note 11:
Property, Plant and Equipment

Property, plant and equipment are recorded at historical cost, net of accumulated depreciation. Components of property, plant and equipment, net are summarized as follows:

  As of December 31,
(In millions) 2025 2024
Land $ 216.7   $ 202.4  
Buildings 2,140.3   1,963.7  
Leasehold improvements 143.5   137.8  
Machinery and equipment 2,167.4   2,109.8  
Computer software and hardware 1,093.5   1,070.5  
Furniture and fixtures 62.1   59.5  
Construction in progress 163.1   308.4  
Total cost (1)
5,986.6   5,852.1  
Less: accumulated depreciation ( 2,931.2 ) ( 2,670.8 )
Total property, plant and equipment, net $ 3,055.4   $ 3,181.3  

(1) During the first quarter of 2024 the second manufacturing suite at our Solothurn, Switzerland facility become operational, resulting in approximately $ 717.3 million of fixed assets being placed into service.
Depreciation expense totaled $ 272.8 million, $ 286.7 million and $ 254.2 million for the years ended December 31, 2025, 2024 and 2023, respectively.
For the years ended December 31, 2025, 2024 and 2023, we capitalized interest costs related to construction in progress totaling approximately $ 3.4 million, $ 3.2 million and $ 21.7 million, respectively.

Note 12:
Leases

We lease real estate, including laboratory and office space, and certain equipment.
Our leases have remaining lease terms ranging from less than one year to twenty-two years . Certain leases include one or more options to renew, exercised at our sole discretion, with renewal terms that can extend the lease term from less than one year to fifteen years .
In addition, we sublease certain real estate to third parties. Our sublease portfolio consists of operating leases, with remaining lease terms ranging from three years to four years .
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BIOGEN INC. AND SUBSIDIARIES
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

All of our leases qualify as operating leases. The following table summarizes the presentation in our consolidated balance sheets of our operating leases:

As of December 31,
(In millions) Balance sheet location 2025 2024
Assets:
Operating lease assets Operating lease assets $ 265.4   $ 356.4  

Liabilities
Current operating lease liabilities Accrued expense and other $ 80.4   $ 86.4  
Non-current operating lease liabilities Long-term operating lease liabilities 290.4   334.5  
Total operating lease liabilities $ 370.8   $ 420.9  

The following table summarizes the effect of lease costs in our consolidated statements of income:

For the Years Ended December 31,
(In millions) Income Statement Location 2025 2024 2023
Operating lease cost Research and development $ 0.9   $ 2.4   $ 2.0  
Selling, general and administrative 100.7   110.1   128.1  
Variable lease cost Research and development 0.1   0.4   0.5  
Selling, general and administrative 34.5   31.2   37.3  
Sublease income Selling, general and administrative ( 9.6 ) ( 14.8 ) ( 23.5 )
Other (income) expense, net ( 4.0 ) ( 4.0 ) ( 4.1 )
Net lease cost $ 122.6   $ 125.3   $ 140.3  

Variable lease cost primarily related to operating expense, taxes and insurance associated with our operating leases. As these costs are generally variable in nature, they are not included in the measurement of the operating lease asset and related lease liability.
The minimum lease payments for the next five years and thereafter are expected to be as follows:

(In millions) As of December 31, 2025
2026 $ 94.1  
2027 97.5  
2028 56.4  
2029 26.1  
2030 23.1  
Thereafter 148.3  
Total lease payments 445.5  
Less: interest 74.7  
Present value of operating lease liabilities $ 370.8  

The weighted average remaining lease term and weighted average discount rate of our operating leases are as follows:

As of December 31,
2025 2024
Weighted average remaining lease term in years 7.11 7.20
Weighted average discount rate 4.6   % 4.5   %

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BIOGEN INC. AND SUBSIDIARIES
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

Supplemental disclosure of cash flow information related to our operating leases included in cash flow provided by operating activities in our consolidated statements of cash flow is as follows:

As of December 31,
(In millions) 2025 2024 2023
Cash paid for amounts included in the measurement of lease liabilities $ 110.7   $ 115.8   $ 116.4  
Operating lease assets obtained in exchange for lease obligations 30.7   16.9   146.0  

New Corporate Headquarters Lease
In March 2025 we entered into a lease agreement with MIT Investment Management Company and BioMed Realty for the lease of approximately 580,000 square feet of office and research and development space located at 75 Broadway, Cambridge, Massachusetts, which will be used as our new global corporate headquarters, as well as integrating our research and development and technical operations teams alongside our North American commercial organization. As part of a multi-year real estate consolidation plan that is expected to result in a reduction of approximately 40 % of our real estate footprint in Massachusetts, this new lease is intended to replace two existing leases, both in Cambridge, Massachusetts, including our current corporate headquarters. We expect the initial lease term of approximately 15.5 years to commence on May 31, 2028. The estimated minimum lease payments as a result of the new lease total approximately $ 1.5  billion over the initial lease term. We have an option to extend the lease for three extension periods of five years each and one six-month short-term extension, at then market-based rates. We will account for this lease as a right-of-use asset and lease liability upon the lease commencement date.
For additional information on our accounting policies relating to leases, please read Note 1, Summary of Significant Accounting Policies - Leases , to these consolidated financial statements.
Reata Lease
As part of our acquisition of Reata, we assumed responsibility for a single-tenant, build-to-suit building of approximately 327,400 square feet of office and laboratory space located in Plano, Texas, with an initial lease term of 16 years. We recorded a lease liability of approximately $ 151.8  million, with a corresponding right-of-use asset of approximately $ 121.2  million. We are continuing to evaluate opportunities to sublease the property.
During the fourth quarter of 2025 we performed an impairment assessment for this right-of use asset. This assessment involved estimating undiscounted future cash flows, including potential sublease income and remaining lease obligations. Given the carrying value exceeded the estimated undiscounted cash flows, primarily as the result of lower expected sublease income, we determined fair value using market data for similar properties and a probability-adjusted discounted cash flow calculation using a discount rate of 5.0 %. As a result of this impairment assessment, we recorded an impairment charge of approximately $ 52.9  million related to this Reata lease, which is included in impairment of ROU asset within our consolidated statements of income for the year ended December 31, 2025. This fair value measurement was based on significant inputs that are not observable in the market and thus represent a Level 3 fair value measurement.
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BIOGEN INC. AND SUBSIDIARIES
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)

Note 13:
Indebtedness

Our indebtedness is summarized as follows:

  As of December 31,
(In millions) 2025 2024
Current portion:
4.050 % Senior Notes due September 15, 2025
$ —   $ 1,748.6  
Current portion of notes payable $ —   $ 1,748.6  
Non-current portion:
2.250 % Senior Notes due May 1, 2030
$ 1,495.7   $ 1,494.7  
5.050 % Senior Notes due January 15, 2031
398.0   —  
5.750 % Senior Notes due May 15, 2035
645.5   —  
5.200 % Senior Notes due September 15, 2045
1,101.5   1,101.1  
3.150 % Senior Notes due May 1, 2050
1,475.6   1,475.0  
3.250 % Senior Notes due February 15, 2051
480.3   476.4  
6.450 % Senior Notes due May 15, 2055
690.2   —  
Non-current portion of notes payable $ 6,286.8   $ 4,547.2  

As of December 31, 2025, we were in compliance with our senior note covenants.
2025 Senior Notes
On May 12, 2025, we issued senior unsecured notes for an aggregate principal amount of $ 1.75  billion, consisting of the following:
• $ 400.0 million of 5.050 % Senior Notes due January 15, 2031, valued at 99.981 % of par;
• $ 650.0 million of 5.750 % Senior Notes due May 15, 2035, valued at 99.924 % of par; and
• $ 700.0 million of 6.450 % Senior Notes due May 15, 2055, valued at 99.657 % of par.
Our 2025 Senior Notes are senior unsecured obligations and may be redeemed at our option at any time at 100 % of the principal amount plus accrued interest and, until a specified period before maturity, a specified make-whole amount. Our 2025 Senior Notes contain a change-of-control provision that, under certain circumstances, may require us to purchase our 2025 Senior Notes at a price equal to 101 % of the principal amount plus accrued and unpaid interest to the date of repurchase.
We incurred approximately $ 13.9 million of costs associated with this offering which have been recorded as a reduction to the carrying amount of the debt on our consolidated balance sheets. These costs will be amortized as additional interest expense using the effective interest rate method over the period from issuance through maturity. The discounts will be amortized as additional interest expense over the period from issuance through maturity using the effective interest rate method.
Interest on our 2031 Senior Notes is payable January 15 and July 15 of each year, commencing January 15, 2026. Interest on our 2035 Senior Notes and 2055 Senior Notes is payable May 15 and November 15 of each year, commencing on November 15, 2025.
2023 Term Loan Credit Agreement
In connection with our acquisition of Reata in September 2023 we entered into a $ 1.5  billion term loan credit agreement. On the closing date of the Reata acquisition we drew $ 1.0  billion from the 2023 Term Loan, comprised of a $ 500.0  million floating rate 364-day tranche and a $ 500.0  million floating rate three-year tranche. The remaining unused commitment of $ 500.0  million was terminated. As of December 31, 2023, we repaid $ 350.0  million of the 364-day tranche. The remaining $ 150.0  million portion of the 364-day tranche was repaid during the first quarter of 2024.
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Additionally, during the first quarter of 2024 we repaid $ 250.0 million of the three-year tranche, with the remaining $ 250.0  million portion being subsequently repaid in full during the second quarter of 2024. For additional information on our acquisition of Reata, please read Note 2, Acquisitions , to these consolidated financial statements.
2021 Exchange Offer Senior Notes
The following is a summary of our currently outstanding senior unsecured notes issued in 2021 as part of our Exchange Offer (the 2021 Exchange Offer Senior Notes), consisting of the following:
• $ 700.7  million aggregate principal amount of 3.25 % Senior Notes due February 15, 2051, valued at 99.298 % of par.
Our 2021 Exchange Offer Senior Notes are senior unsecured obligations and may be redeemed at our option at any time at 100.0 % of the principal amount plus accrued interest and a specified make-whole amount. Our 2021 Exchange Offer Senior Notes contain a change of control provision that may require us to purchase the notes at a price equal to 101.0 % of the principal amount plus accrued and unpaid interest to the date of purchase under certain circumstances.
The costs associated with this exchange offer of approximately $ 5.4  million have been recorded as a reduction to the carrying amount of the debt in our consolidated balance sheets. These costs along with the discounts will be amortized as additional interest expense using the effective interest rate method over the period from issuance through maturity. Interest on our 2021 Exchange Offer Senior Notes is payable February 15 and August 15 of each year, commencing August 15, 2021.
2020 Senior Notes
The following is a summary of our currently outstanding senior unsecured notes issued in 2020 (2020 Senior Notes), consisting of the following:
• $ 1.5  billion aggregate principal amount of 2.250 % Senior Notes due May 1, 2030, valued at 99.973 % of par; and
• $ 1.5  billion aggregate principal amount of 3.150 % Senior Notes due May 1, 2050, valued at 99.174 % of par.
Our 2020 Senior Notes are senior unsecured obligations and may be redeemed at our option at any time at 100.0 % of the principal amount plus accrued interest and, until a specified period before maturity, a specified make-whole amount. Our 2020 Senior Notes contain a change-of-control provision that, under certain circumstances, may require us to purchase our 2020 Senior Notes at a price equal to 101.0 % of the principal amount plus accrued and unpaid interest to the date of repurchase.
The original costs associated with this offering of approximately $ 24.4  million have been recorded as a reduction to the carrying amount of the debt in our consolidated balance sheets. These costs along with the discounts will be amortized as additional interest expense using the effective interest rate method over the period from issuance through maturity. Interest on our 2020 Senior Notes is payable May 1 and November 1 of each year, commencing November 1, 2020.
2015 Senior Notes
The following is a summary of our currently outstanding senior unsecured notes issued in 2015 (the 2015 Senior Notes), consisting of the following:
• $ 1.12 billion aggregate principal amount of 5.200 % Senior Notes due September 15, 2045, valued at 99.294 % of par.
Our 2015 Senior Notes are senior unsecured obligations and may be redeemed at our option at any time at 100.0 % of the principal amount plus accrued interest and a specified make-whole amount. Our 2015 Senior Notes contain a change of control provision that may require us to purchase the notes at a price equal to 101.0 % of the principal amount plus accrued and unpaid interest to the date of purchase under certain circumstances.
The original costs associated with this offering of approximately $ 47.5 million, of which approximately $ 10.7  million pertains to our currently outstanding notes, have been recorded as a reduction to the carrying amount of the debt in our consolidated balance sheets. These costs along with the discounts will be amortized as additional interest expense using the effective interest rate method over the period from issuance through maturity. Interest on our 2015 Senior Notes is payable March 15 and September 15 of each year, commencing March 15, 2016.
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4.050 % Senior Notes due September 15, 2025
On September 15, 2015, we issued $ 1.75 billion aggregate principal amount of 4.050 % Senior Notes due September 15, 2025, at 99.764 % of par. In June 2025 we used the net proceeds from the sale of our 2025 Senior Notes to redeem our 4.050 % Senior Notes due September 15, 2025, prior to maturity. No gain or loss was recognized upon redemption.
2024 Revolving Credit Facility
In August 2024 we entered into a $ 1.5 billion, five-year senior unsecured revolving credit facility under which we are permitted to draw funds for working capital and general corporate purposes. The terms of the revolving credit facility include a financial covenant that requires us not to exceed a maximum consolidated leverage ratio. This revolving credit facility replaced the revolving credit facility that we entered into in January 2020. As of December 31, 2025, we had no outstanding borrowings and were in compliance with all covenants under this facility.
Debt Maturity
The total gross principal payments due under our debt arrangements are as follows:

(In millions) As of December 31, 2025
2026 $ —  
2027 —  
2028 —  
2029 —  
2030 1,500.0  
2031 and thereafter 5,067.3  
Total current and non-current debt
6,567.3  
Less: debt discount and issuance fees ( 280.5 )
Total current and non-current debt, net
$ 6,286.8  

The fair value of our debt is disclosed in Note 8, Fair Value Measurements, to these consolidated financial statements.

Note 14:
Equity

Preferred Stock
We have 8.0 million shares of Preferred Stock authorized, of which 1.75 million shares are authorized as Series A, 1.0 million shares are authorized as Series X junior participating and 5.25 million shares are undesignated. Shares may be issued without a vote or action of shareholders from time to time in classes or series with the designations, powers, preferences and the relative, participating, optional or other special rights of the shares of each such class or series and any qualifications, limitations or restrictions thereon as set forth in the instruments governing such shares. Any such Preferred Stock may rank prior to common stock as to dividend rights, liquidation preference or both, and may have full or limited voting rights and may be convertible into shares of common stock. No shares of Preferred Stock were issued and outstanding during 2025, 2024 and 2023.
Common Stock
The following table describes the number of shares authorized, issued and outstanding of our common stock as of December 31, 2025, 2024 and 2023:

  As of December 31, 2025 As of December 31, 2024 As of December 31, 2023
(In millions) Authorized Issued Outstanding Authorized Issued Outstanding Authorized Issued Outstanding
Common stock 1,000.0   170.5   146.8   1,000.0   169.5   145.8   1,000.0   168.7   144.9  

Share Repurchases
In October 2020 our Board of Directors authorized our 2020 Share Repurchase Program, which is a program to repurchase up to $ 5.0 billion of our common stock. Our 2020 Share Repurchase Program does not have an expiration date. All shares repurchased under our 2020 Share Repurc hase Program were retired. There were no
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repurchases of our common stock during the years ended December 31, 2025, 2024 and 2023. Approximately $ 2.1  billion remained available under our 2020 Share Repurchase Program as of December 31, 2025.
Amounts paid to repurchase shares in excess of their par value are allocated between additional paid-in-capital and retained earnings, with payments in excess of our additional paid-in-capital balance recorded as a reduction to retained earnings.
Accumulated Other Comprehensive Income (Loss)
The following tables summarize the changes in AOCI, net of tax by component:

December 31, 2025
(In millions) Unrealized Gains (Losses) on Securities Available for Sale, Net of Tax Unrealized Gains (Losses) on Cash Flow Hedges,
Net of Tax Unrealized Gains (Losses) on Pension Benefit Obligation,
Net of Tax Currency
Translation
Adjustments,
Net of Tax Total
Balance, December 31, 2024 $ —   $ 51.6   $ ( 16.6 ) $ ( 171.2 ) $ ( 136.2 )
Other comprehensive income (loss) before reclassifications 0.2   ( 156.4 ) 7.2   57.3   ( 91.7 )
Amounts reclassified from AOCI —   45.9   —   —   45.9  
Net current period other comprehensive income (loss) 0.2   ( 110.5 ) 7.2   57.3   ( 45.8 )
Balance, December 31, 2025 $ 0.2   $ ( 58.9 ) $ ( 9.4 ) $ ( 113.9 ) $ ( 182.0 )

December 31, 2024
(In millions) Unrealized Gains (Losses) on Cash Flow Hedges,
Net of Tax Unrealized Gains (Losses) on Pension Benefit Obligation,
Net of Tax Currency Translation Adjustments,
Net of Tax Total
Balance, December 31, 2023 $ ( 25.0 ) $ ( 2.6 ) $ ( 126.1 ) $ ( 153.7 )
Other comprehensive income (loss) before reclassifications 80.8   ( 14.0 ) ( 45.1 ) 21.7  
Amounts reclassified from AOCI ( 4.2 ) —   —   ( 4.2 )
Net current period other comprehensive income (loss) 76.6   ( 14.0 ) ( 45.1 ) 17.5  
Balance, December 31, 2024 $ 51.6   $ ( 16.6 ) $ ( 171.2 ) $ ( 136.2 )

December 31, 2023
(In millions) Unrealized Gains (Losses) on Securities Available for Sale,
Net of Tax Unrealized Gains (Losses) on Cash Flow Hedges,
Net of Tax Unrealized Gains (Losses) on Pension Benefit Obligation,
Net of Tax Currency Translation Adjustments,
Net of Tax Total
Balance, December 31, 2022 $ ( 15.7 ) $ 15.1   $ ( 1.1 ) $ ( 163.2 ) $ ( 164.9 )
Other comprehensive income (loss) before reclassifications 2.3   ( 26.8 ) ( 1.5 ) 37.1   11.1  
Amounts reclassified from AOCI 13.4   ( 13.3 ) —   —   0.1  
Net current period other comprehensive income (loss) 15.7   ( 40.1 ) ( 1.5 ) 37.1   11.2  
Balance, December 31, 2023 $ —   $ ( 25.0 ) $ ( 2.6 ) $ ( 126.1 ) $ ( 153.7 )

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The following table summarizes the amounts reclassified from AOCI:

(In millions) Amounts Reclassified from AOCI Income Statement Location
For the Years Ended December 31,
2025 2024 2023
Gains (losses) on securities available for sale $ —   $ —   $ ( 17.0 ) Other (income) expense, net
—   —   3.6   Income tax (benefit) expense

Gains (losses) on cash flow hedges ( 72.4 ) 18.1   11.6   Revenue
21.3   ( 12.9 ) 3.7   Operating expense
( 0.3 ) ( 0.4 ) ( 0.3 ) Other (income) expense, net
5.5   ( 0.6 ) ( 1.7 ) Income tax (benefit) expense
Total reclassifications, net of tax $ ( 45.9 ) $ 4.2   $ ( 0.1 )

Note 15:
Earnings per Share

Basic and diluted shares outstanding used in our earnings per share calculation are calculated as follows:

  For the Years Ended December 31,
(In millions) 2025 2024 2023
Numerator:
Net income attributable to Biogen Inc. $ 1,292.9   $ 1,632.2   $ 1,161.1  
Denominator:
Weighted-average number of common shares outstanding 146.5   145.6   144.7  
Effect of dilutive securities:

Time-vested restricted stock units 0.5   0.3   0.7  
Performance stock units settled in stock 0.1   —   0.2  
Dilutive potential common shares 0.6   0.3   0.9  
Shares used in calculating diluted earnings per share 147.1   145.9   145.6  

Amounts excluded from the calculation of net income per diluted share because their effects were anti-dilutive were insignificant.

Note 16:
Share-Based Payments

Share-Based Compensation Expense
The following table summarizes share-based compensation expense included in our consolidated statements of income:

  For the Years Ended December 31,
(In millions) 2025 2024 2023
Research and development $ 115.7   $ 154.1   $ 296.7  
Selling, general and administrative 187.8   198.6   371.7  
Subtotal 303.5   352.7   668.4  
Capitalized share-based compensation costs ( 12.4 ) ( 10.3 ) ( 10.2 )
Share-based compensation expense included in total cost and expense 291.1   342.4   658.2  
Income tax effect ( 57.0 ) ( 63.4 ) ( 132.6 )
Share-based compensation expense included in net income attributable to Biogen Inc. $ 234.1   $ 279.0   $ 525.6  

In connection with our acquisition of HI-Bio in July 2024 we recognized HI-Bio equity-based compensation expense, inclusive of employer taxes, of approximately $ 56.4  million attributable to the post-acquisition service period, of which $ 42.5  million was recognized as a charge to research and development expense with the remaining $ 13.9  million as a charge to selling, general and administrative expense within our consolidated statements of
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income for the year ended December 31, 2024. These amounts were associated with the accelerated vesting of stock options and RSUs previously granted to HI-Bio employees and required no future services to vest.
In connection with our acquisition of Reata in September 2023 we recognized Reata equity-based compensation expense, inclusive of employer taxes, of approximately $ 393.4  million attributable to the post-acquisition service period, of which $ 196.4  million was recognized as a charge to selling, general and administrative expense with the remaining $ 197.0  million as a charge to research and development expense within our consolidated statements of income for the year ended December 31, 2023. These amounts were associated with the accelerated vesting of stock options and RSUs previously granted to Reata employees that required no future services to vest.
For additional information on our acquisitions of HI-Bio and Reata, please read Note 2, Acquisitions , to these consolidated financial statements.
The following table summarizes share-based compensation expense associated with each of our share-based compensation programs:

  For the Years Ended December 31,
(In millions) 2025 2024 2023
Time-vested restricted stock units $ 249.3   $ 236.4   $ 220.0  
Performance stock units settled in stock 42.3   48.4   35.5  
Performance stock units settled in cash —   ( 2.5 ) 6.8  
Employee stock purchase plan 8.4   9.7   10.5  
Stock options 3.5   3.7   3.7  
Market stock units —   0.6   4.9  
Reata equity awards (1)
—   —   387.0  
HI-Bio equity awards (1)
—   56.4   —  
Subtotal 303.5   352.7   668.4  
Capitalized share-based compensation costs ( 12.4 ) ( 10.3 ) ( 10.2 )
Share-based compensation expense included in total cost and expense $ 291.1   $ 342.4   $ 658.2  

(1) Relates to the Reata and HI-Bio equity-based compensation expense attributable to the post-acquisition service period, associated with the accelerated vesting of stock options and RSUs previously granted to Reata and HI-Bio employees that required no future services to vest. For additional information on our acquisitions of Reata and HI-Bio, please read Note 2, Acquisitions , to these consolidated financial statements.
As of December 31, 2025, unrecognized compensation cost related to unvested share-based compensation was approximately $ 292.6 million, net of estimated forfeitures. We expect to recognize the cost of these unvested awards over a weighted-average period of 1.9 years.
Share-Based Compensation Plans
We have two share-based compensation plans pursuant to which awards are currently being made: (i) the Biogen Inc. 2024 Omnibus Equity Plan (2024 Omnibus Equity Plan); and (ii) the Biogen Inc. 2024 Employee Stock Purchase Plan (2024 ESPP).
We have three share-based compensation plans pursuant to which outstanding awards have been made, but from which no further awards can or will be made: (i) the Biogen Inc. 2006 Non-Employee Directors Equity Plan (2006 Directors Plan); (ii) the Biogen Inc. 2017 Omnibus Equity Plan (2017 Omnibus Equity Plan); and (iii) the Biogen Inc. 2015 Employee Stock Purchase Plan (2015 ESPP).
2024 Omnibus Equity Plan
In June 2024 our shareholders approved the 2024 Omnibus Equity Plan for share-based awards to our prospective and current employees, non-employee directors, officers or consultants. Awards granted from the 2024 Omnibus Equity Plan may include stock options, shares of restricted stock, restricted stock units, performance shares, stock appreciation rights and other awards in such amounts and with such terms and conditions as may be determined by a committee of our Board of Directors, subject to the provisions of the plan. Shares of common stock available for grant under the 2024 Omnibus Equity Plan consist of 3.7  million shares reserved for this purpose, plus shares of common stock that remained available for grant under our 2017 Omnibus Equity Plan (including shares available by
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reason of a predecessor plan) on the date that our shareholders approved the 2024 Omnibus Equity Plan, plus shares that were subject to awards under the 2017 Omnibus Equity Plan (including shares available by reason of a predecessor plan) that remain unissued upon the cancellation, surrender, exchange, termination or forfeiture of such awards. The 2024 Omnibus Equity Plan provides that awards other than stock options and stock appreciation rights will be counted against the total number of shares available under the plan in a 1.5 -to-1 ratio.
We have not made any awards pursuant to the 2017 Omnibus Equity Plan or the Directors Plan since our shareholders approved the 2024 Omnibus Equity Plan, and do not intend to make any awards pursuant to the 2017 Omnibus Equity Plan or the Directors Plan in the future, except that unused shares under the 2017 Omnibus Equity Plan have been carried over for use under the 2024 Omnibus Equity Plan. Awards outstanding under the 2017 Omnibus Equity Plan and the Directors Plan as of the date our shareholders approved the 2024 Omnibus Equity Plan will remain outstanding and subject to the terms and conditions of the 2017 Omnibus Equity Plan and the Directors Plan, as applicable, and the relevant award agreements.
Stock Options
In 2022 we granted approximately 81,000 stock options to our CEO (2022 CEO Grant) under the 2017 Omnibus Plan with a grant date fair value of $ 139.10 per option for a total of approximately $ 11.2  million. The fair value of the stock option grant is estimated as of the date of grant using a Black-Scholes option valuation model. The estimated fair value of the stock option is then expensed over the options' vesting periods. The 2022 CEO Grant is eligible to vest in equal annual installments over a three-year period from the grant date, subject to the CEO’s continued employment. The outstanding stock option has a 10-year term and is exercisable at a price per share not less than the fair market value of the underlying common stock on the date of grant.

December 31, 2025
Shares Weighted Average
Exercise Price
Weighted Average Remaining Contractual Term

Outstanding at December 31, 2024 81,000   $ 301.85   7.9 years
Granted —   —  
Exercised
—   —  
Forfeited —   —  
Outstanding at December 31, 2025 81,000   $ 301.85   6.9 years
Exercisable at December 31, 2025 81,000   $ 301.85   6.9 years

Market Stock Units
MSUs awarded to employees in 2014 and thereafter vested in three equal annual increments beginning on the first anniversary of the grant date, and participants could ultimately earn between zero and 200.0 % of the target number of units granted based on actual stock performance. The vesting of these awards was subject to the respective employee’s continued employment.
Beginning in 2022 we no longer grant MSUs as part of our long term incentive program and have replaced with granting performance-vested RSUs. The fair values of the remaining MSUs vested in 2024 and 2023 totaled $ 6.3 million and $ 20.7 million, respectively.
Performance Stock Units
PSUs Settled in Stock
During the first quarter of 2018 we began granting awards for performance-vested RSUs that will settle in stock. PSUs awarded to employees have a three-year performance period and vest on the third anniversary of the grant date. The vesting of these awards is subject to the respective employee’s continued employment. The number of PSUs granted represents the target number of units that are eligible to be earned based on the achievement of cumulative three-year performance measures established at the beginning of the performance period, which ends on December 31 of the third year of the performance period.
Participants may ultimately earn between zero and 200.0 % of the target number of PSUs granted based on the degree of achievement of the applicable performance metric. Accordingly, additional PSUs may be issued or currently outstanding PSUs may be cancelled upon final determination of the number of units earned.
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Beginning in 2022 we no longer grant MSUs as part of our long term incentive program and have replaced with granting PSUs with a performance metric based on a three-year cumulative relative total shareholder return (rTSR) metric.
Beginning in 2024 we began granting PSUs with a performance metric based on the three-year cumulative aggregate growth rate of our earnings per share during the performance period.
The following table summarizes our PSUs that settle in stock activity:

December 31, 2025
Shares Weighted Average
Grant Date Fair Value
Unvested at December 31, 2024 550,000   $ 310.61  
Granted (1)
477,000   161.28  
Vested —   —  
Forfeited ( 222,000 ) 176.41  
Unvested at December 31, 2025 805,000   $ 227.39  

(1) PSUs settled in stock granted in 2025 include awards granted in conjunction with our annual awards made in February 2025 and PSUs granted in conjunction with the hiring of employees. These grants reflect the target number of shares eligible to be earned at the time of grant.
PSUs settled in stock granted in 2024 and 2023 had weighted average grant date fair values of $ 280.60 and $ 383.61 , respectively.
We value grants of PSUs with a performance metric based on a three-year cumulative rTSR metric using a lattice model with a Monte Carlo simulation. This valuation methodology utilizes several key assumptions, the 30 calendar day average closing stock price on the date of grant for PSUs, expected volatility of our stock price, risk-free rates of return and expected dividend yield.
The assumptions used in our valuation are summarized as follows:

  For the Years Ended December 31,
  2025 2024 2023
Expected dividend yield — %
— %
— %

Range of expected stock price volatility 34.5 %
35.1 %
44.7 %

Range of risk-free interest rates 4.2 %
4.1 %
4.1 %

30 calendar day average stock price on grant date $ 146.46
$ 251.69
$ 283.93

Weighted-average per share grant date fair value $ 196.13
$ 280.60
$ 383.61

The fair values of PSUs settled in stock that vested in 2024 and 2023 totaled $ 13.2  million and $ 28.6  million, respectively.
PSUs Settled in Cash
During the first quarter of 2018 we began granting awards for performance-vested restricted stock units that would settle in cash. PSUs awarded to employees had three performance periods and vested on the third anniversary of the grant date. The vesting of these awards was subject to the respective employee’s continued employment. PSUs were classified as liability awards and were settled in cash based on the 30 calendar day average closing stock price through the vesting date, once the actual vested and earned number of PSUs was determined. Since no shares were issued, these awards did not dilute equity.
Beginning in 2022 we no longer grant PSUs settled in cash as part of our long term incentive program and have replaced with granting time-vested RSUs. The fair values of the remaining PSUs settled in cash that vested in 2024 and 2023 totaled $ 9.5  million and $ 11.7  million, respectively.
Time-Vested Restricted Stock Units
RSUs awarded to employees generally vest no sooner than one-third per year over three years on the anniversary of the date of grant, or upon the third anniversary of the date of the grant, provided the employee remains continuously employed with us, except as otherwise provided in the plan. Shares of our common stock will be delivered to the employee upon vesting, subject to payment of applicable withholding taxes. RSUs awarded to directors for service on
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our Board of Directors vest on the first anniversary of the date of grant, provided in each case that the director continues to serve on our Board of Directors through the vesting date. Shares of our common stock will be delivered to the director upon vesting and are not subject to any withholding taxes.
The following table summarizes our RSU activity:

Shares Weighted Average
Grant Date Fair Value
Unvested at December 31, 2024 2,051,000   $ 246.22  
Granted (1)
2,385,000   141.71  
Vested ( 997,000 ) 243.92  
Forfeited ( 363,000 ) 188.28  
Unvested at December 31, 2025 3,076,000   $ 172.75  

(1) RSUs granted in 2025 primarily represent RSUs granted in conjunction with our annual awards made in February 2025 and awards made in conjunction with the hiring of new employees. RSUs granted in 2025 also include approximately 24,500 RSUs granted to our Board of Directors.
RSUs granted in 2024 and 2023 had weighted average grant date fair values of $ 235.82 and $ 282.92 , respectively.
The fair values of RSUs vested in 2025, 2024 and 2023 totaled $ 141.6 million, $ 193.6 million and $ 232.1 million, respectively.
Employee Stock Purchase Plan
2024 Employee Stock Purchase Plan
In June 2024 our shareholders approved the 2024 ESPP. The 2024 ESPP, which became effective on July 1, 2024, replaced the 2015 ESPP, which expired on June 30, 2024. The maximum number of shares of our common stock that may be purchased under the 2024 ESPP is 2.5  million.
The following table summarizes our ESPP activity:

  For the Years Ended December 31,
(In millions, except share amounts) 2025 2024 2023
Shares issued under the 2024 ESPP 295,000   40,000   —  
Shares issued under the 2015 ESPP —   175,000   199,000  
Cash received under the 2024 ESPP $ 34.0   $ 5.1   $ —  
Cash received under the 2015 ESPP $ —   $ 31.2   $ 45.1  

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Note 17:
Income Taxes

Income Tax Expense
Income before income tax (benefit) expense and the income tax (benefit) expense consist of the following:

  For the Years Ended December 31,
(In millions) 2025 2024 2023
Income before income tax (benefit) expense:
Domestic $ 1,225.2   $ 853.4   $ 192.4  
Foreign 331.3   1,052.6   1,104.4  
Total income before income tax (benefit) expense $ 1,556.5   $ 1,906.0   $ 1,296.8  
Income tax (benefit) expense:
Current:
Federal $ 10.1   $ 448.9   $ 377.6  
State 47.3   50.5   15.1  
Foreign ( 155.4 ) ( 67.5 ) 48.4  
Total current ( 98.0 ) 431.9   441.1  
Deferred:
Federal 346.1   ( 154.5 ) ( 587.4 )
State ( 25.1 ) ( 17.3 ) ( 12.7 )
Foreign 40.6   13.7   294.3  
Total deferred 361.6   ( 158.1 ) ( 305.8 )
Total income tax (benefit) expense $ 263.6   $ 273.8   $ 135.3  

The lower Federal current provision in 2025 reflects the impact of a tax deduction for certain previously deferred capitalized research and development expenditures under the OBBBA and the impact of recording a capital loss on our sale of Sage common stock.
Foreign current benefit reflects the non-cash benefit of current year valuation allowance changes.
Transition Toll Tax
The Tax Cuts and Jobs Act of 2017 eliminated the deferral of U.S. income tax on the historical unrepatriated earnings by imposing the one-time mandatory deemed repatriation tax on accumulated foreign subsidiaries' previously untaxed foreign earnings. The Transition Toll Tax was assessed on our share of our foreign corporations' accumulated foreign earnings that were not previously taxed. Earnings in the form of cash and cash equivalents were taxed at a rate of 15.5% and all other earnings were taxed at a rate of 8.0%.
As of December 31, 2024, we accrued income tax liabilities of approximately $ 234.0 million under the Transition Toll Tax, which was subsequently paid in full in April 2025.
Unremitted Earnings
At December 31, 2025, we considered our earnings not to be permanently reinvested outside the U.S. and therefore recorded deferred tax liabilities associated with an estimate of the total withholding taxes expected as a result of our repatriation of earnings. Other than for earnings, we are permanently reinvested for book/tax basis differences, primarily arising through the impacts of purchase accounting. These permanently reinvested basis differences could reverse through sales of the foreign subsidiaries, as well as various other events, none of which were considered probable as of December 31, 2025. The residual U.S. tax liability, if these differences reverse, would be between $ 300.0 million and $ 400.0 million as of December 31, 2025.
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Deferred Tax Assets and Liabilities
Significant components of our deferred tax assets and liabilities are summarized as follows:

  As of December 31,
(In millions) 2025 2024
Deferred tax assets:
Tax credits $ 286.1   $ 294.0  
Inventory, other reserves and accruals 246.9   219.2  
Intangibles, net 886.5   989.6  

Capitalized research and development 457.2   733.9  
Net operating loss 1,082.8   1,357.2  
Share-based compensation 36.1   34.4  
Other 141.7   318.4  
Valuation allowance ( 832.2 ) ( 1,013.7 )
Total deferred tax assets $ 2,305.1   $ 2,933.0  
Deferred tax liabilities:
Purchased inventory valuation step-up and intangible assets
$ ( 1,456.1 ) $ ( 1,529.6 )

GILTI ( 891.3 ) ( 1,054.8 )

Depreciation, amortization and other ( 172.8 ) ( 214.9 )
Total deferred tax liabilities $ ( 2,520.2 ) $ ( 2,799.3 )

As of December 31, 2025, 2024, 2023 and 2022, we had a valuation allowance of $ 832.2  million, $ 1,013.7  million, $ 1,278.7  million and $ 2,003.3  million, respectively, related to net operating losses in Switzerland and Neurimmune's tax basis in ADUHELM.
The change in the valuation allowance between December 31, 2025 and 2024, was primarily driven by movements in net operating loss deferred tax assets in Switzerland. The net income tax impact of the changes in the valuation allowance was a benefit of approximately $ 37.9  million for the year ended December 31, 2025.
The change in the valuation allowance between December 31, 2024 and 2023, was primarily driven by movements in net operating loss deferred tax assets in Switzerland. The net income tax impact of the changes in the valuation allowance was a benefit of approximately $ 56.8  million for the year ended December 31, 2024.
The change in the valuation allowance between December 31, 2023 and 2022, was primarily driven by a reduction of approximately $ 470.3  million related to the elimination of Neurimmune's tax basis in ADUHELM as a result of its deconsolidation and reduction of approximately $ 230.3  million due to movements in net operating loss deferred tax assets in Switzerland. The net income tax impact of the changes in the valuation allowance was an expense of approximately $ 7.4  million for the year ended December 31, 2023. For additional information on the deconsolidation and our collaboration arrangement with Neurimmune, please read Note 20, Investments in Variable Interest Entities , to these consolidated financial statements.
In addition to deferred tax assets and liabilities, we have recorded deferred charges related to intra-entity sales of inventory. As of December 31, 2025 and 2024, the total deferred charges were $ 498.8 million and $ 273.1 million, respectively.
2025 OBBBA Tax Provisions
On July 4, 2025, the U.S. signed into law the H.R.1 legislation formally titled "An Act to Provide for Reconciliation Pursuant to Title II of H. Con. Res. 14", commonly referred to as the OBBBA.
The OBBBA contains tax provisions, such as the permanent extension or revision of certain expiring provisions of the Tax Cuts and Jobs Act enacted in 2017, modifications to the international tax framework and the restoration of favorable tax treatment for certain business provisions. The provisions of the OBBBA have multiple effective dates, with certain provisions effective in 2025 and others implemented through 2027. The OBBBA did not result in any material adjustments to our total income tax provision for the year ended December 31, 2025, and we have adjusted our deferred tax balances to reflect the impacts of the OBBBA enactment.
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Pillar Two
The OECD has issued model rules, which generally provide for a jurisdictional minimum effective tax rate of 15.0% as defined in those rules. Various countries have or are in the process of enacting legislation intended to implement the principles. Our income tax provision for the years ended December 31, 2025 and 2024, reflects currently enacted legislation and guidance related to the OECD model rules including the Pillar Two side-by-side package announced by the OECD in January 2026. This enacted legislation and guidance related to the OECD model rules did not result in any material adjustments to our income tax provision or income tax balances as of December 31, 2025 and 2024.
Tax Rate
For the year ended December 31, 2025, we adopted ASU 2023-09 on a prospective basis. In preparing the tabular rate reconciliation, we are presenting the effects of cross-border tax laws net of the related U.S. tax credits. The tax effects for all jurisdictions of changes in judgment related to tax positions taken in prior annual reporting periods, and associated interest, are reported in the changes in unrecognized tax benefits category. Unrecognized tax benefits related to current year tax positions are shown net with the reconciling item that relates to the uncertain tax position.
The following table is a reconciliation of the U.S. federal statutory rate of 21.0% to our effective tax rate for the year ended December 31, 2025, in accordance with the guidance in ASU 2023-09.

For the Year Ended December 31, 2025
(In millions, except percentages) Amount Rate
Statutory rate $ 326.9   21.0   %
State and local income taxes, net of federal income tax effect (1)
8.5   0.5  
Foreign tax effects:
Italy
Withholding tax ( 20.4 ) ( 1.3 )
Other 1.8   0.1  
Switzerland
Statutory tax rate difference ( 22.1 ) ( 1.4 )
Cantonal tax impact 11.9   0.8  
Pillar Two taxes ( 17.2 ) ( 1.1 )
Changes in valuation allowances ( 190.2 ) ( 12.2 )
Taxable intercompany dividend 22.8   1.5  
Other ( 6.1 ) ( 0.4 )
U.K.
Litigation matter 21.0   1.3  
Other 0.7   —  
Other foreign jurisdictions 9.5   0.6  
Effects of changes in tax laws or rates ( 11.5 ) ( 0.7 )
Effects of cross-border tax laws
GILTI, net of foreign tax credits 88.0   5.7  
Other, net of foreign tax credits 18.5   1.2  
Tax Credits
Orphan drug credits ( 31.3 ) ( 2.0 )
Other credits ( 4.5 ) ( 0.3 )
Nontaxable or nondeductible items
Equity compensation 18.9   1.2  
Other permanent differences 16.9   1.1  
Changes in unrecognized tax benefits 9.6   0.6  
Other adjustments 11.9   0.7  
Income tax expense and effective tax rate $ 263.6   16.9   %

(1) State taxes in Tennessee, Massachusetts, Kentucky and North Carolina made up the majority (greater than 50.0%) of the tax effect in this category.
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The following table is a reconciliation of the U.S. federal statutory tax rate of 21.0% to our effective tax rate for the years ended December 31, 2024 and 2023, in accordance with the guidance prior to the adoption of ASU 2023-09:

  For the Years Ended December 31,
  2024 2023
Statutory rate 21.0   % 21.0   %
State taxes 1.8   1.1  
Taxes on foreign earnings, including valuation allowances ( 7.6 ) ( 5.9 )
Tax credits ( 2.2 ) ( 7.3 )
Purchased inventory valuation step-up and intangible assets
2.1   0.7  

GILTI ( 1.6 ) ( 0.6 )

Internal reorganization —   ( 0.1 )
Other, including permanent items 0.9   1.5  
Effective tax rate 14.4   % 10.4   %

In the reconciliation for the year ended December 31, 2025, in accordance with the guidance in ASU 2023-09, the GILTI foreign tax credit impacts of changes in foreign valuation allowances are included within the GILTI, net of foreign tax credits line. For reconciliation for the years ended December 31, 2024 and 2023, the GILTI foreign tax credit impacts of changes in foreign valuation allowances are included within the taxes on foreign earnings, including valuation allowances line.
Changes in Tax Rate
For the year ended December 31, 2025, compared to 2024, the increase in our effective tax rate was partially driven by changes in the territorial mix of our profitability and the impact of certain share-based compensation awards that vested during the first quarter of 2025, partially offset by the impact of the elimination of Italian withholding tax.
For the year ended December 31, 2024, compared to 2023, the increase in our effective tax rate was partially driven by the relative deferred tax effects of the changes in the value of our equity investments and amortization of purchased intangible assets and inventory. Further, 2023 benefited from the combined impacts of Reata acquisition-related expenses and the resolution of an uncertain tax matter related to tax credits. This was partially offset by a 2024 benefit related to a decrease in our valuation allowance related to projected future foreign taxable income, as discussed in the Deferred Tax Assets and Liabilities section above.
For additional information on our acquisition of Reata, please read Note 2, Acquisitions , to these consolidated financial statements.
Tax Attributes
As of December 31, 2025, we had credit carry forwards for U.S. federal income tax purposes of approximately $ 146.2 million that begin to expire in 2030 and net operating losses of approximately $ 142.8  million that do not expire. For U.S. state income tax purposes, we had research and investment credit carry forwards of approximately $ 172.1 million that begin to expire in 2027 and net operating losses of approximately $ 356.6  million that begin to expire in 2028. For foreign income tax purposes, we had $ 9.1 billion of federal net operating loss carryforwards that begin to expire in 2027 and $ 8.4  billion of Swiss cantonal net operating loss carryforwards that begin to expire in 2027.
In assessing the realizability of our deferred tax assets, we have considered whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. In making this determination, under the applicable financial reporting standards, we are allowed to consider the scheduled reversal of deferred tax liabilities, projected future taxable income and tax planning strategies. Based upon the level of historical taxable income and income tax liability and projections for future taxable income over the periods in which the deferred tax assets are utilizable, we believe it is more likely than not that we will realize the net benefits of the deferred tax assets of our wholly owned subsidiaries, net of the recorded valuation allowance. In the event that actual results differ from our estimates or we adjust our estimates in future
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periods, we may need to adjust or establish a valuation allowance, which could materially impact our consolidated financial position and results of operations.
Income Taxes Paid
The following table presents income taxes paid (net of refunds received) for the year ended December 31, 2025.

(In millions) For the Year Ended December 31, 2025
Federal $ 721.0  
State 48.4
Foreign 94.6
Total $ 864.0  

No individual state or foreign jurisdiction accounted for 5.0% or more of the total taxes paid in 2025.
Accounting for Uncertainty in Income Taxes
A reconciliation of the beginning and ending amount of our unrecognized tax benefits is summarized as follows:

For the Years Ended December 31,
(In millions) 2025 2024 2023
Beginning balance $ 186.3   $ 173.4   $ 606.4  
Additions based on tax positions related to the current period 3.6   1.2   5.2  
Additions for tax positions of prior periods 12.4   31.5   60.2  
Reductions for tax positions of prior periods ( 3.9 ) ( 3.1 ) ( 485.0 )
Statute expirations ( 6.6 ) ( 12.7 ) ( 2.1 )
Settlement refund (payment) ( 11.8 ) ( 4.0 ) ( 11.3 )
Ending balance $ 180.0   $ 186.3   $ 173.4  

As of December 31, 2022, the unrecognized tax benefits related to a deferred tax asset for Swiss tax purposes for Neurimmune's tax basis in ADUHELM was approximately $ 450.0  million. This unrecognized tax benefit was recorded as a reduction to the gross deferred tax asset, resulting in a net deferred tax asset and not as a separate liability on our consolidated balance sheets. During the year ended December 31, 2023, we decreased our gross unrecognized tax benefits by approximately $ 450.0  million related to this item as a result of the deconsolidation of Neurimmune.
We file income tax returns in various U.S. states and in U.S. federal and other foreign jurisdictions. With few exceptions, we are no longer subject to U.S. federal tax examination for years before 2022 or state, local or non-U.S. income tax examinations for years before 2013.
Included in the balance of unrecognized tax benefits as of December 31, 2025, 2024 and 2023, are $ 127.6 million, $ 139.3 million and $ 147.6 million (net of the federal benefit on state issues), respectively, of unrecognized tax benefits that, if recognized, would affect the effective income tax rate in future periods.
We recognize potential interest and penalties related to unrecognized tax benefits in income tax (benefit) expense within our consolidated statements of income. During the years ended December 31, 2025, 2024 and 2023, we recognized total interest and penalty expense of $ 12.6 million, $ 13.8 million and $ 5.1 million, respectively. We have accrued $ 48.5 million and $ 40.7 million for the payment of interest and penalties as of December 31, 2025 and 2024, respectively.
It is reasonably possible that we will adjust the value of our uncertain tax positions related to certain transfer pricing, collaboration matters, withholding taxes and other issues as we receive additional information from various taxing authorities, including reaching settlements with such authorities.
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Note 18:
Other Consolidated Financial Statement Detail

Supplemental Cash Flow Information
Supplemental disclosure of cash flow information is summarized as follows:

  For the Years Ended December 31,
(In millions) 2025 2024 2023
Cash paid during the year for:
Interest $ 264.1   $ 245.4   $ 252.2  
Income taxes 864.0   355.1   740.7  

Other (Income) Expense, Net
Components of other (income) expense, net, are summarized as follows:

  For the Years Ended December 31,
(In millions) 2025 2024 2023
Interest income $ ( 125.0 ) $ ( 67.6 ) $ ( 276.5 )
Interest expense 267.5   250.3   246.9  
(Gains) losses on investments, net 19.7   100.4   291.2  
Litigation related expense 139.5   26.3   3.9  
Foreign exchange (gains) losses, net 28.6   30.9   50.4  
Other, net ( 24.7 ) 3.3   ( 0.4 )
Total other (income) expense, net $ 305.6   $ 343.6   $ 315.5  

The (gains) losses on investments, net, as reflected in the table above, relate to debt securities, equity securities of certain biotechnology companies, venture capital funds where the underlying investments are in equity securities of certain biotechnology companies and non-marketable equity securities.
In 2025 we recorded $ 139.5 million related to various litigation matters, including our agreement in principle to resolve all claims relating to Biogen's acquisition of Convergence. For additional information on our legal matters, please read Note 21, Litigation , to these consolidated financial statements.
The following table summarizes our (gains) losses on investments, net that relate to our equity securities held during the following periods:

  For the Years Ended December 31,
(In millions) 2025 2024 2023
Net (gains) losses recognized on equity securities $ 19.7   $ 100.4   $ 275.2  
Less: Net (gains) losses realized on equity securities 1.5   ( 2.0 ) 5.2  
Net unrealized (gains) losses recognized on equity securities $ 18.2   $ 102.4   $ 270.0  

The net unrealized losses recognized during the year ended December 31, 2025, primarily reflect a decrease in the aggregate fair value of our investment in Denali common stock of approximately $ 27.7  million, partially offset by an increase in the fair value of Sage common stock of approximately $ 23.0  million.
The net unrealized losses recognized during the year ended December 31, 2024, primarily reflect a decrease in the aggregate fair value of our investment in Sage common stock of approximately $ 101.4  million, partially offset by an increase in the fair value of Denali and Sangamo common stock of approximately $ 7.5  million.
The net unrealized losses recognized during the year ended December 31, 2023, primarily reflect a decrease in the aggregate fair value of our investments in Sage, Denali, Sangamo and Ionis common stock of approximately $ 248.5  million.
Other Current Assets
Other current assets includes prepaid taxes of $ 693.6 million and $ 307.2 million as of December 31, 2025 and 2024, respectively.
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Accrued Expense and Other
Accrued expense and other consists of the following:

  As of December 31,
(In millions) 2025 2024

Revenue-related reserves for discounts and allowances $ 1,000.4   $ 937.5  
Employee compensation and benefits 375.8   375.8  
Collaboration expense 280.0   309.0  
Royalties and licensing fees 302.4   190.2  

Current portion of contingent consideration obligations —   291.2  

Other 844.0   704.0  
Total accrued expense and other $ 2,802.6   $ 2,807.7  

Other Long-term Liabilities
Other long-term liabilities were $ 748.5 million and $ 732.3 million as of December 31, 2025 and 2024, respectively, and included accrued income taxes totaling $ 166.4 million and $ 156.7 million, respectively.

Note 19:
Collaborative and Other Relationships

In connection with our business strategy, we have entered into various collaboration agreements that provide us with rights to develop, produce and market products using certain know-how, technology and patent rights maintained by our collaborative partners. Terms of the various collaboration agreements may require us to make milestone payments upon the achievement of certain product research and development objectives and pay royalties on future sales, if any, of commercial products resulting from the collaboration.
Depending on the collaborative arrangement, we may record funding receivable or payable balances with our collaboration partners, based on the nature of the cost-sharing mechanism and activity within the collaboration. Our significant collaborative arrangements are discussed below.
Genentech, Inc. (Roche Group)
We have certain business and financial rights with respect to RITUXAN for the treatment of non-Hodgkin's lymphoma, CLL and other conditions; RITUXAN HYCELA for the treatment of non-Hodgkin's lymphoma and CLL; GAZYVA for the treatment of CLL, follicular lymphoma and, following its approval in October 2025, lupus nephritis; OCREVUS for the treatment of PPMS and RMS; LUNSUMIO for the treatment of relapsed or refractory follicular lymphoma; COLUMVI, a bispecific antibody for the treatment of non-Hodgkin's lymphoma; and have the option to add other potential anti-CD20 therapies, pursuant to our collaboration arrangements with Genentech, a wholly owned member of the Roche Group. For purposes of this footnote, we refer to RITUXAN and RITUXAN HYCELA collectively as RITUXAN.
Our collaboration with Genentech was created through a contractual arrangement and not through a joint venture or other legal entity.
RITUXAN
Under our collaboration with Genentech, we are entitled to a tiered share of co-promotion operating profits and losses of RITUXAN in the U.S., as summarized in the table below. Genentech and its affiliates are responsible for the worldwide manufacture of RITUXAN as well as all development and commercialization activities as follows:
• U.S.: We have co-exclusively licensed our rights to develop, commercialize and market RITUXAN in the U.S.
• Canada: We have co-exclusively licensed our rights to develop, commercialize and market RITUXAN in Canada.
If we undergo a change in control, as defined in our collaboration agreement, Genentech has the right to present an offer to buy the rights to RITUXAN and we must either accept Genentech’s offer or purchase Genentech’s rights on the same terms as its offer. Genentech will also be deemed concurrently to have purchased our rights to the remaining products in the collaboration on the terms set forth below.
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GAZYVA
The Roche Group and its sub-licensees maintain sole responsibility for the development, manufacture and commercialization of GAZYVA and we are entitled to a tiered share of co-promotion operating profits and losses of GAZYVA in the U.S. The level of gross sales of GAZYVA in the U.S. has impacted our percentage of the co-promotion profits for RITUXAN and LUNSUMIO, as summarized in the table below.
If we undergo a change in control, as defined in our collaboration agreement, Genentech will be deemed to have purchased our rights to GAZYVA in exchange for the continued payment of the current compensation payable for GAZYVA under the collaboration arrangement until the 11 year anniversary of the first commercial sale of GAZYVA in the U.S.
OCREVUS
Pursuant to the terms of our collaboration arrangements with Genentech, we receive a tiered royalty on U.S. net sales from 13.5 % and increasing up to 24.0 % if annual net sales exceed $ 900.0 million. There will be a 50.0 % reduction to these royalties upon the first entry of an FDA approved biosimilar to OCREVUS.
In addition, we receive a gross 3.0 % royalty on net sales of OCREVUS outside the U.S., with the royalty period lasting 11 years from the first commercial sale of OCREVUS on a country-by-country basis.
The commercialization of OCREVUS does not impact the percentage of the co-promotion profits we receive for RITUXAN, LUNSUMIO or GAZYVA. Genentech is solely responsible for development and commercialization of OCREVUS and funding future costs. Genentech cannot develop OCREVUS in CLL, non-Hodgkin's lymphoma or rheumatoid arthritis.
OCREVUS royalty revenue is based on our estimates from third party and market research data of OCREVUS sales occurring during the corresponding period. Differences between actual and estimated royalty revenue will be adjusted for in the period in which they become known, which is generally expected to be the following quarter.
If we undergo a change in control, as defined in our collaboration agreement, Genentech will be deemed to have purchased our rights to OCREVUS in exchange for the continued payment of the current royalties on net sales (as defined in our collaboration agreement and summarized above) in the U.S. only, until the 11 year anniversary of the first commercial sale of OCREVUS in the U.S.
LUNSUMIO
Under our collaboration with Genentech, we are entitled to a tiered share of co-promotion operating profits and losses in the U.S., as summarized in the table below. In addition, we receive low-single digit royalties on sales of LUNSUMIO outside the U.S.
If we undergo a change in control, as defined in our collaboration agreement, Genentech will be deemed to have purchased our rights to LUNSUMIO in exchange for 30.0 % of the U.S. co-promotion operating profits or losses until the 11 year anniversary of the first commercial sale of LUNSUMIO in the U.S.
COLUMVI
Genentech has sole decision-making rights on the commercialization of COLUMVI within the U.S. and we receive tiered royalties in the mid-single digit range on net sales of COLUMVI in the U.S. The commercialization of COLUMVI does not impact the percentage of the co-promotion profits we receive for RITUXAN, LUNSUMIO or GAZYVA.
If we undergo a change in control, as defined in our collaboration agreement, Genentech will be deemed to have purchased our rights to COLUMVI in exchange for a mid-single digit royalty on net sales (as defined in our collaboration agreement) in the U.S. only, until the 11 year anniversary of the first commercial sale of the product in the U.S.
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Profit-sharing Formulas
RITUXAN and LUNSUMIO Profit Share
Our current pre-tax co-promotion profit-sharing formula for RITUXAN and LUNSUMIO in the U.S. provides for a 30.0 % share on the first $ 50.0 million of combined co-promotion operating profits earned each calendar year. Our share of the combined annual co-promotion profits for RITUXAN and LUNSUMIO in excess of $ 50.0 million varies upon the following events, as summarized in the table below:

After LUNSUMIO Approval until the First Threshold Date 37.5   %
After First Threshold Date until the Second Threshold Date 35.0   %
After Second Threshold Date 30.0   %

In March 2023 the First Threshold Date was achieved when U.S. gross sales of GAZYVA within a consecutive 12-month period reached $ 500.0 million. As a result, beginning in April 2023 the pre-tax profit share for RITUXAN and LUNSUMIO has been 35.0 %. The Second Threshold Date would be achieved on the first date in any calendar year in which U.S. gross sales of LUNSUMIO have reached $ 350.0 million.
GAZYVA Profit Share
Our current pretax profit-sharing formula for GAZYVA provides for a 35.0 % share on the first $ 50.0 million of operating profits earned in the U.S. in each calendar year. In March 2023 U.S. gross sales of GAZYVA within a consecutive 12-month period reached $ 500.0 million. As a result, beginning in April 2023 the pre-tax profit share for GAZYVA decreased from 37.5 % to 35.0 %.
Revenue from Anti-CD20 Therapeutic Programs
Revenue from anti-CD20 therapeutic programs is summarized as follows:

  For the Years Ended December 31,
(In millions) 2025 2024 2023
Royalty revenue on sales of OCREVUS $ 1,414.9   $ 1,339.5   $ 1,266.2  
Biogen's share of pre-tax profits in the U.S. for RITUXAN, GAZYVA and LUNSUMIO 420.2   392.0   409.4  
Other revenue from anti-CD20 therapeutic programs 25.5   18.4   14.0  
Total revenue from anti-CD20 therapeutic programs $ 1,860.6   $ 1,749.9   $ 1,689.6  

Prior to regulatory approval, we record our share of the expense incurred by the collaboration for the development of anti-CD20 products in research and development expense and pre-commercialization costs within selling, general and administrative expense in our consolidated statements of income. After an anti-CD20 product is approved, we record our share of the development and sales and marketing expense related to that product as a reduction of our share of pre-tax profits in revenue from anti-CD20 therapeutic programs.
Ionis Pharmaceuticals, Inc.
SPINRAZA
In January 2012 we entered into a collaboration and license agreement with Ionis pursuant to which we have an exclusive, worldwide license to develop and commercialize SPINRAZA for the treatment of SMA.
Under our agreement with Ionis, we make royalty payments to Ionis on annual worldwide net sales of SPINRAZA using a tiered royalty rate between 11.0 % and 15.0 %, which are recognized in cost of sales within our consolidated statements of income. Royalty cost of sales related to sales of SPINRAZA for the years ended December 31, 2025, 2024 and 2023, totaled approximately $ 212.3  million, $ 216.1  million and $ 240.2  million, respectively.
2018 Ionis Agreement
In June 2018 we entered into a 10-year exclusive collaboration agreement with Ionis to develop novel ASO drug candidates for a broad range of neurological diseases for a total payment of $ 1.0 billion, consisting of an upfront payment of $ 375.0 million and the purchase of approximately 11.5 million shares of Ionis common stock at a cost of $ 625.0 million.
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We have the option to license therapies arising out of this agreement and will be responsible for the development and commercialization of such therapies. We may pay development milestones to Ionis of up to $ 125.0 million or $ 270.0 million for each program, depending on the indication plus an annual license fee, as well as royalties on potential net commercial sales.
During the years ended December 31, 2025, 2024 and 2023, we incurred milestones of $ 7.5  million, $ 7.5 million and $ 7.5  million, respectively, related to the advancement of neurological targets identified under this agreement, which were recorded as research and development expense in our consolidated statements of income.
2017 SMA Collaboration Agreement
In December 2017 we entered into a collaboration agreement with Ionis to identify new ASO drug candidates for the potential treatment of SMA. Under this agreement, we have options to license therapies arising out of this collaboration and will be responsible for the development and commercialization of such therapies.
In December 2021 we exercised our option with Ionis and obtained a worldwide, exclusive, royalty-bearing license to develop and commercialize salanersen (BIIB115), an investigational ASO in development for SMA.
We may pay Ionis up to $ 155.0 million in additional development and regulatory milestone payments related to salanersen, including a $ 45.0 million milestone payment due upon the initiation of a Phase 3 trial. Upon commercialization, we may also pay Ionis up to $ 400.0 million in additional performance-based milestone payments and tiered royalties on potential net sales of such therapies ranging from the mid-teens to high-twenties percentages.
2013 Long-term Strategic Research Agreement
In September 2013 we entered into a six-year research collaboration agreement with Ionis under which both companies collaborated to perform discovery level research and subsequent development and commercialization activities of antisense or other therapeutics for the potential treatment of neurological diseases.
In December 2018 we exercised our option with Ionis and obtained a worldwide, exclusive, royalty-bearing license to develop and commercialize QALSODY (tofersen), for the treatment of ALS with SOD1 mutations. Following the option exercise, we are solely responsible for the costs and expense related to the development, manufacturing and commercialization of QALSODY.
In April 2023 the FDA approved QALSODY for the treatment of ALS in adults who have a mutation in the SOD1 gene. This indication is approved under accelerated approval based on reduction in plasma neurofilament light chain observed in patients treated with QALSODY. Continued approval for this indication may be contingent upon verification of clinical benefit in confirmatory trial(s). Under this agreement, we make royalty payments to Ionis on annual worldwide net sales of QALSODY using a tiered royalty rate between 11.0 % and 15.0 %, which are recognized in cost of sales within our consolidated statements of income.
During the year ended December 31, 2024, we incurred a milestone payment of $ 20.0  million to Ionis following the approval of QALSODY in the E.U., which was recorded within intangible assets, net in our consolidated balance sheets. Additionally, during the year ended December 31, 2024, we accrued a milestone payment of $ 10.0  million to Ionis following the approval of QALSODY in Japan, which was recorded within intangible assets, net in our consolidated balance sheets, and paid during the first quarter of 2025.
During the year ended December 31, 2023, we incurred a milestone payment of $ 16.0  million to Ionis following the FDA's approval of QALSODY, which was recorded within intangible assets, net in our consolidated balance sheets.
2012 Ionis Agreement
In December 2012 we entered into an agreement with Ionis for the development and commercialization of up to three gene targets.
In December 2019 we exercised our option with Ionis and obtained a worldwide, exclusive, royalty-bearing license to develop and commercialize BIIB080 (tau ASO), which is currently in Phase 2 development for the potential treatment of Alzheimer's disease. Following the option exercise, we are solely responsible for global development, regulatory and commercialization. Future payments may include additional milestone payments of up to $ 155.0 million and royalties on future sales in the low- to mid-teens if we successfully develop the product candidate after option exercise.
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Eisai Co., Ltd.
During the first quarter of 2023 we accrued a $ 31.0  million payable to Eisai related to the termination of an agreement whereby Eisai co-promoted or distributed our MS products in certain Asia-Pacific markets and settings. As of December 31, 2023, we paid approximately $ 16.0  million of the $ 31.0  million payable. The remaining portion was subsequently paid in January 2024. This termination fee is included in selling, general and administrative expense in our consolidated statements of income for the year ended December 31, 2023.
LEQEMBI (lecanemab) Collaboration
We have a collaboration agreement with Eisai to jointly develop and commercialize LEQEMBI (lecanemab), an anti-amyloid antibody for the treatment of Alzheimer's disease. The FDA granted traditional approval of LEQEMBI in July 2023. Prior to receiving traditional approval, LEQEMBI had been granted accelerated approval by the FDA in January 2023, at which time it became commercially available in the U.S. Outside of the U.S., LEQEMBI is now approved in the E.U. (April 2025), Australia (September 2025), China (January 2024), Japan (September 2023) and other international markets. LEQEMBI monthly IV maintenance dosing for the treatment of early Alzheimer's disease was approved in the U.S. and China in January 2025 and September 2025, respectively, and LEQEMBI subcutaneous autoinjector (IQLIK) for weekly maintenance dosing was approved in the U.S. in August 2025.
All costs, including research, development, sales and marketing expense, are shared equally between us and Eisai. We also share profits and losses equally. We currently have a supply agreement with Eisai to manufacture LEQEMBI drug substance and drug product through the end of 2031.
Subject to the limitations in the LEQEMBI Collaboration Agreement, Eisai has final decision-making authority on all matters relating to the collaboration and serves as the lead of LEQEMBI development and regulatory submissions globally. We co-commercialize and co-promote LEQEMBI with Eisai. Our Collaboration Agreement provides that each commercialization plan shall allocate the responsibilities for the activities under the plan in an equitable fashion taking into account Biogen's and Eisai's respective capabilities and provides a meaningful role for each party.
Upon commercialization of LEQEMBI in the U.S., we began recognizing our 50.0 % share of LEQEMBI product revenue, net and cost of sales, including royalties, within Alzheimer's collaboration revenue in our consolidated statements of income, as we are not the principal.
Our share of LEQEMBI sales and marketing expense and development expense are recorded within selling, general and administrative expense and research and development expense, respectively, within our consolidated statements of income.
If either company undergoes a change of control, as defined in our LEQEMBI Collaboration Agreement, the non-acquired party may elect to initiate an operational separation, as defined in the LEQEMBI Collaboration Agreement. In the event of an operational separation, we would work with Eisai to effect a timely transition of any development, manufacturing or commercial responsibilities regarding LEQEMBI from us to Eisai. In this scenario, as of six months following the change of control, our ongoing responsibility for LEQEMBI related cost-sharing would be reduced to an amount equal to 80.0 % of what we would have owed prior to the operational separation, and all other economic rights would remain unchanged.
In addition, in the event either company undergoes a change of control in which the acquirer is engaged in commercialization of a competing product, as defined in the LEQEMBI Collaboration Agreement, the non-acquired party may also request that the acquired party cease commercializing the competing product. Should the acquired party elect to continue commercializing the competing product, the non-acquired party may terminate the LEQEMBI Collaboration Agreement. Furthermore, in the event we are the non-acquired party, we may choose either to sell our interest in LEQEMBI to Eisai or purchase Eisai's interest in LEQEMBI, subject to the parameters set forth in the LEQEMBI Collaboration Agreement.
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A summary of development and sales and marketing expense related to the LEQEMBI Collaboration is as follows:

  For the Years Ended December 31,
(In millions) 2025 2024 2023
Total development expense incurred by the collaboration related to the advancement of LEQEMBI $ 253.1   $ 329.6   $ 371.9  
Biogen's share of the LEQEMBI Collaboration development expense reflected in research and development expense in our consolidated statements of income 126.5   164.8   186.0  
Total sales and marketing expense incurred by the LEQEMBI Collaboration 701.6   647.0   304.4  
Biogen's share of the LEQEMBI Collaboration sales and marketing expense reflected in selling, general and administrative expense in our consolidated statements of income 350.8   323.5   152.2  

Amounts receivable from Eisai related to the agreements discussed above we re approximately $ 90.2  million a nd $ 16.7  million as of December 31, 2025 and 2024, respectively. Amounts payable to Eisai related to the agreements discussed above we re approximately $ 95.5  million a nd $ 138.0  million as of December 31, 2025 and 2024, respectively.
UCB
We have a collaboration agreement with UCB, effective November 2003, to jointly develop and commercialize dapirolizumab pegol, an anti-CD40L pegylated Fab, for the potential treatment of SLE and other future agreed indications. Either we or UCB may propose development of dapirolizumab pegol in additional indications. If the parties do not agree to add an indication as an agreed indication to the collaboration, we or UCB may, at the sole expense of the applicable party, pursue development in such excluded indication(s), subject to an opt-in right of the non-pursuing party after proof of clinical activity.
All costs incurred for agreed indications, including research, development, sales and marketing expense, are shared equally between us and UCB. If marketing approval is obtained, both companies will jointly commercialize dapirolizumab pegol and share profits and losses equally.
A summary of development expense related to the UCB collaboration agreement is as follows:

For the Years Ended December 31,
(In millions) 2025 2024 2023
Total UCB collaboration development expense $ 79.9   $ 77.5   $ 60.7  
Biogen's share of the UCB collaboration development expense reflected in research and development expense in our consolidated statements of income 39.9   38.7   30.3  

Supernus Pharmaceuticals, Inc. (previously Sage Therapeutics, Inc.)
In November 2020 we entered into a global collaboration and license agreement with Sage to jointly develop and commercialize ZURZUVAE (zuranolone) for the treatment of PPD. In July 2025 Sage was acquired by Supernus. ZURZUVAE was approved in the U.S. in August 2023 and in the E.U. in September 2025. Upon approval, ZURZUVAE became the first and only oral, once-daily, 14-day treatment that can provide rapid improvements in depressive symptoms by day 15 for women with PPD.
Under this collaboration, both companies will share equal responsibility and costs for development as well as profits and losses for commercialization in the U.S. Outside of the U.S., we are responsible for development and commercialization, excluding Japan, Taiwan and South Korea, with respect to zuranolone and may pay Supernus potential tiered royalties in the high-teens to low-twenties percentages. During the fourth quarter of 2023 we accrued a milestone payment due to Sage of $ 75.0  million upon the first commercial sale of ZURZUVAE for PPD in the U.S., which was recorded within intangible assets, net in our consolidated balance sheets, and subsequently paid in January 2024.
We may pay Supernus development and commercial milestone payments that could total up to approximately $ 700.0  million if all the specified milestones set forth in this collaboration are achieved.
We reflect revenue on sales of ZURZUVAE to third parties in product revenue, net in our consolidated statements of income and record the related cost of revenue and sales and marketing expense in our consolidated statements of income to their respective line items when these costs are incurred.
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We share 50.0 % of the net collaboration results in the U.S. with Supernus, which are recognized in collaboration profit sharing/(loss reimbursement) in our consolidated statements of income. For the years ended December 31, 2025, 2024 and 2023, we recognized net profit-sharing expense of approximately $ 71.0 million and $ 27.0  million, and net loss reimbursement of approximately $ 4.7  million, respectively, to reflect Supernus' 50.0 % share of net collaboration results in the U.S.
A summary of development and sales and marketing expense related to the Supernus collaboration is as follows:

For the Years Ended December 31,
(In millions) 2025 2024 2023
Total Supernus collaboration development expense $ 2.7   $ 34.2   $ 176.7  
Biogen's share of the Supernus collaboration development expense reflected in research and development expense in our consolidated statements of income 1.3   17.1   88.3  
Total sales and marketing expense incurred by the Supernus collaboration 173.0   118.5   187.0  
Biogen's share of the Supernus collaboration sales and marketing expense reflected in selling, general and administrative expense and collaboration profit sharing/(loss reimbursement) in our consolidated statements of income 86.5   59.2   93.5  

Denali Therapeutics Inc.
In August 2020 we entered into a collaboration and license agreement with Denali to co-develop and co-commercialize BIIB122, a small molecule inhibitor of LRRK2 for Parkinson's disease (LRRK2 Collaboration).
We may pay Denali development and commercial milestone payments that could total up to approximately $ 1.1  billion if the milestones related to the LRRK2 Collaboration are achieved.
Under the LRRK2 Collaboration, both companies share responsibility and costs for global development based on specified percentages as well as profits and losses for commercialization in the U.S. and China. Outside the U.S. and China we are responsible for commercialization and may pay Denali potential tiered royalties.
A summary of development expense related to the Denali collaboration is as follows:

For the Years Ended December 31,
(In millions) 2025 2024 2023
Total Denali collaboration development expense $ 44.1   $ 53.1   $ 65.0  
Biogen's share of the Denali collaboration development expense reflected in research and development expense in our consolidated statements of income 26.5   31.9   39.0  

Stoke Therapeutics, Inc.
In February 2025 we entered into a collaboration and license agreement with Stoke to co-develop and commercialize zorevunersen, an investigational ASO that targets the SCN1A gene for the potential treatment of Dravet syndrome, a rare form of genetic epilepsy associated with refractory seizures and neurodevelopmental impairments. Zorevunersen dosed its first patient in August 2025, advancing zorevunersen to a global Phase 3 trial.
Under the terms of this agreement, Stoke will continue to lead global development and retain exclusive development and commercialization rights for zorevunersen in the U.S., Canada and Mexico and we will have exclusive rights to commercialize zorevunersen in the rest of the world. Both companies will share responsibility for external clinical development costs, where Stoke is responsible for 70.0 % of these development costs and we are responsible for the remaining 30.0 % of these development costs.
In connection with the closing of this transaction we made an upfront payment of $ 165.0 million to Stoke, which was recognized in acquired in-process research and development, upfront and milestone expense within our consolidated statements of income for the year ended December 31, 2025. We may also pay Stoke potential development and commercial milestone payments of up to $ 50.0 million and $ 335.0 million, respectively, if all the specified milestones set forth in this collaboration are achieved. In addition, we may pay Stoke tiered royalties on potential net sales of any products developed under this collaboration in the low-double digit to high-teen percentages.
We also have an exclusive option to license certain future follow-on ASO products targeting the SCN1A gene in all territories worldwide other than the U.S., Canada and Mexico, in exchange for separate milestone, cost sharing and royalty considerations.
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A summary of development expense related to the Stoke collaboration agreement is as follows:

(In millions) For the Year Ended December 31, 2025
Total Stoke collaboration development expense $ 39.4  
Biogen's share of the Stoke collaboration development expense reflected in research and development expense in our consolidated statements of income 11.8