0000872589-26-000008 | 10-K | XBRL Viewer | Regeneron Pharmaceuticals INC

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Fair Value Measurements - Schedule of Unrealized Gains On Investments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Net gains (losses) recognized during the period	$ 955.6	$ 117.7	$ (235.6)
Less: Net gains recognized on investments sold during the period	966.2	0.0	6.0
Net unrealized gains (losses) recognized on investments still held as of period end date	$ (10.6)	$ 117.7	$ (241.6)

Insider Trading Policies and Procedures	12 Months Ended
Insider Trading Policies and Procedures	Dec. 31, 2025
Insider Trading Policies and Procedures [Line Items]
Insider Trading Policies and Procedures Adopted	true

Marketable Securities

12 Months Ended

Dec. 31, 2025

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

Marketable securities as of December 31, 2025 and 2024 consist of both available-for-sale debt securities of investment grade issuers (see below and Note 5) as well as equity securities of publicly traded companies (see Note 5).

The following tables summarize the Company's investments in available-for-sale debt securities:


(In millions)	Amortized		Unrealized				Fair
As of December 31, 2025	Cost Basis		Gains		Losses		Value
Corporate bonds	$	10,141.0	$	80.9	$	(2.4)	$	10,219.5
U.S. government and government agency obligations	4,352.2		15.2		(0.1)		4,367.3
Commercial paper	540.8		0.3		—		541.1
Certificates of deposit	265.7		0.2		—		265.9
Asset-backed securities	241.4		1.4		—		242.8
Sovereign bonds	76.3		0.5		—		76.8
	$	15,617.4	$	98.5	$	(2.5)	$	15,713.4

As of December 31, 2024
Corporate bonds	$	8,226.9	$	25.1	$	(31.4)	$	8,220.6
U.S. government and government agency obligations	4,820.5		3.4		(6.9)		4,817.0
Commercial paper	548.3		0.4		—		548.7
Certificates of deposit	380.6		0.5		—		381.1
Asset-backed securities	279.0		0.6		(0.3)		279.3
Sovereign bonds	82.7		0.1		(0.4)		82.4
	$	14,338.0	$	30.1	$	(39.0)	$	14,329.1

The Company classifies its investments in available-for-sale debt securities based on their contractual maturity dates. The available-for-sale debt securities as of December 31, 2025 mature at various dates through December 2032. The fair values of available-for-sale debt securities by contractual maturity consist of the following:


	As of December 31,
(In millions)	2025		2024
Maturities within one year	$	5,487.1	$	6,524.3
Maturities after one year through five years	10,224.8		7,804.8
Maturities after five years	1.5		—
	$	15,713.4	$	14,329.1

Amounts reclassified from Accumulated other comprehensive income (loss) into Other income (expense), net related to realized gains/losses on sales of available-for-sale debt securities; such amounts were not material for the years ended December 31, 2025, 2024, and 2023.

The Company recognized interest income of $716.8 million, $711.4 million, and $495.9 million for the years ended December 31, 2025, 2024, and 2023, respectively, in Other income (expense), net.

Marketable Securities - Schedule of Investments in Available For Sale Debt Securities (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	$ 15,617.4	$ 14,338.0
Unrealized Gains	98.5	30.1
Unrealized Losses	(2.5)	(39.0)
Fair Value	15,713.4	14,329.1
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	10,141.0	8,226.9
Unrealized Gains	80.9	25.1
Unrealized Losses	(2.4)	(31.4)
Fair Value	10,219.5	8,220.6
U.S. government and government agency obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	4,352.2	4,820.5
Unrealized Gains	15.2	3.4
Unrealized Losses	(0.1)	(6.9)
Fair Value	4,367.3	4,817.0
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	540.8	548.3
Unrealized Gains	0.3	0.4
Unrealized Losses	0.0	0.0
Fair Value	541.1	548.7
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	265.7	380.6
Unrealized Gains	0.2	0.5
Unrealized Losses	0.0	0.0
Fair Value	265.9	381.1
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	241.4	279.0
Unrealized Gains	1.4	0.6
Unrealized Losses	0.0	(0.3)
Fair Value	242.8	279.3
Sovereign bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	76.3	82.7
Unrealized Gains	0.5	0.1
Unrealized Losses	0.0	(0.4)
Fair Value	$ 76.8	$ 82.4

Cover - USD ($) $ in Billions	12 Months Ended
Cover - USD ($) $ in Billions	Dec. 31, 2025	Jan. 22, 2026	Jun. 30, 2025
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2025
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	000-19034
Entity Registrant Name	REGENERON PHARMACEUTICALS, INC.
Entity Incorporation, State or Country Code	NY
Entity Tax Identification Number	13-3444607
Entity Address, Address Line One	777 Old Saw Mill River Road
Entity Address, City or Town	Tarrytown
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10591-6707
City Area Code	914
Local Phone Number	847-7000
Title of 12(b) Security	Common Stock - par value $.001 per share
Trading Symbol	REGN
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction	false
Entity Shell Company	false
Entity Public Float			$ 54.8
Documents Incorporated by Reference	Specified portions of the Registrant's definitive proxy statement to be filed in connection with solicitation of proxies for its 2026 Annual Meeting of Shareholders are incorporated by reference into Part III of this Form 10-K. Exhibit index is located on pages 91 to 94 of this filing.
Entity Central Index Key	0000872589
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Amendment Flag	false
Class A Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		1,817,146
Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		103,902,660

Employee Savings Plans (Details) - USD ($) $ in Millions	12 Months Ended
Employee Savings Plans (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Retirement Benefits [Abstract]
Employer contribution expense to 401(k) Savings Plan	$ 95.7	$ 90.2	$ 84.7

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2025

Equity [Abstract]

Class of treasury stock

The table below summarizes the shares of the Company's Common Stock that the Company repurchased under its share repurchase programs and the cost of such shares, which were recorded as Treasury Stock.


	Year Ended December 31,
(In millions)	2025		2024		2023
Number of shares	5.6		2.8		2.9
Total cost of shares	$	3,456.2	$	2,613.9	$	2,214.6

Collaboration, License, and Other Agreements - Other Narrative (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2026	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Acquired in-process research and development		$ 124.1	$ 101.0	$ 186.1
Agreements with Royalty Provisions
Disaggregation of Revenue [Line Items]
Royalty rate minimum		0.50%
Royalty rate maximum		12.50%
Royalty expense, net of reimbursements from collaborators		$ 81.3	82.9	117.6
Tessera Therapeutics \| Subsequent Event
Disaggregation of Revenue [Line Items]
Aggregate payment for upfront and equity acquired	$ 150.0
Hanosh Pharmaceutical Group Company Limited
Disaggregation of Revenue [Line Items]
Up-front payment to acquire license rights		$ 80.0
Sonoma Biotherapeutics, Inc.
Disaggregation of Revenue [Line Items]
Acquired in-process research and development			$ 45.0	45.0
Alnylam Pharmaceuticals, Inc
Disaggregation of Revenue [Line Items]
Acquired in-process research and development				100.0
Intellia Therapeutics, Inc.
Disaggregation of Revenue [Line Items]
Acquired in-process research and development				$ 30.0

Long-Term Incentive Plans - Summary of weighted-average exercise prices and weighted-average grant-date fair values of options issued (Details) - Stock options - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options Granted (in shares)	0.7	1.9	1.6
Weighted-Average Exercise Price (in dollars per share)	$ 691.40	$ 786.79	$ 835.91
Weighted-Average Fair Value (in dollars per share)	$ 206.58	$ 235.32	$ 264.37

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Inventories - Schedule of Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Inventory Disclosure [Abstract]
Raw materials	$ 641.5	$ 879.5
Work-in-process	1,641.6	1,342.3
Finished goods	190.2	139.8
Deferred costs	727.5	725.7
Total Inventories	$ 3,200.8	$ 3,087.3

Leases (Tables)

12 Months Ended

Dec. 31, 2025

Leases [Abstract]

Schedule of amounts recognized in the condensed consolidated balance sheet

Amounts recognized in the Consolidated Balance Sheet related to the Company's leases are included in the table below.


		As of December 31,
(In millions)	Classification	2025		2024
Assets:
Finance lease right-of-use assets	Property, plant, and equipment, net(a)	$	576.7	$	591.2
Operating lease right-of-use assets	Other noncurrent assets(b)	245.8		217.4
		$	822.5	$	808.6

Liabilities:
Finance lease liabilities - noncurrent	Finance lease liabilities	$	720.0	$	720.0
Operating lease liabilities - current	Accrued expenses and other current liabilities	37.8		30.3
Operating lease liabilities - noncurrent	Other noncurrent liabilities	229.0		204.1
		$	986.8	$	954.4

(a) Finance lease right-of-use assets were recorded net of accumulated amortization of $162.9 million and $148.4 million as of December 31, 2025 and 2024, respectively
(b) Operating lease right-of-use assets were recorded net of accumulated amortization of $68.8 million and $78.4 million as of December 31, 2025 and 2024, respectively

Schedule of lease cost and other information

Lease costs consist of the following:


	Year Ended December 31,
(In millions)	2025		2024		2023
Operating lease costs	$	35.8	$	36.5	$	19.2
Finance lease costs:
Amortization of finance lease right-of-use assets	14.5		14.5		14.5
Interest on finance lease liabilities	39.1		46.1		45.0
Total finance lease costs	53.6		60.6		59.5

Total lease costs	$	89.4	$	97.1	$	78.7

Other information related to the Company's leases includes the following:


	As of December 31,
	2025	2024
Weighted-average remaining lease term (in years):
Finance leases	1.2	2.2
Operating leases	6.9	7.2
Weighted-average discount rate:
Finance leases	4.40%	5.03%
Operating leases	5.38%	5.52%

Supplemental cash flow information related to the Company's leases includes the following:


	Year Ended December 31,
(In millions)	2025		2024		2023
Cash paid for amounts included in the measurement of operating lease liabilities (included within cash flows from operating activities)	$	39.6	$	41.4	$	22.5
Right-of-use assets obtained in exchange for operating lease liabilities	$	59.1	$	188.1	$	31.9

Schedule of maturities of operating lease liabilities

The following is a maturity analysis of the Company's lease liabilities as of December 31, 2025:


(In millions)	Finance Leases		Operating Leases		Total
2026	$	33.7	$	52.1	$	85.8
2027	727.6		52.3		779.9
2028	—		48.5		48.5
2029	—		40.3		40.3
2030	—		31.2		31.2
Thereafter	—		97.5		97.5
Total undiscounted lease payments	761.3		321.9		1,083.2
Imputed interest	(41.3)		(55.1)		(96.4)
Total lease liabilities	$	720.0	$	266.8	$	986.8

Schedule of maturities of finance lease liabilities

The following is a maturity analysis of the Company's lease liabilities as of December 31, 2025:


(In millions)	Finance Leases		Operating Leases		Total
2026	$	33.7	$	52.1	$	85.8
2027	727.6		52.3		779.9
2028	—		48.5		48.5
2029	—		40.3		40.3
2030	—		31.2		31.2
Thereafter	—		97.5		97.5
Total undiscounted lease payments	761.3		321.9		1,083.2
Imputed interest	(41.3)		(55.1)		(96.4)
Total lease liabilities	$	720.0	$	266.8	$	986.8

Segment Information - Schedule of Significant Expenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Research and development	$ 5,850.2	$ 5,132.0	$ 4,439.0
Reportable Segment
Segment Reporting Information [Line Items]
Research and development	5,850.2	5,132.0	4,439.0
Reimbursement of research and development expenses by collaborators	(148.5)	(190.8)	(176.3)
Reportable Segment \| Clinical manufacturing costs
Segment Reporting Information [Line Items]
Research and development	1,391.2	1,195.9	1,053.9
Reportable Segment \| Priority Review Voucher
Segment Reporting Information [Line Items]
Research and development	155.0	0.0	0.0
Reportable Segment \| Direct research and development expenses
Segment Reporting Information [Line Items]
Research and development	1,758.1	1,588.8	1,295.6
Reportable Segment \| Indirect research and development expenses
Segment Reporting Information [Line Items]
Research and development	2,694.4	2,538.1	2,265.8
Reportable Segment \| Indirect research and development expenses \| Payroll and benefits
Segment Reporting Information [Line Items]
Research and development	1,800.8	1,681.7	1,537.0
Reportable Segment \| Indirect research and development expenses \| Lab supplies and other research and development costs
Segment Reporting Information [Line Items]
Research and development	258.2	241.5	210.6
Reportable Segment \| Indirect research and development expenses \| Occupancy and other operating costs
Segment Reporting Information [Line Items]
Research and development	$ 635.4	$ 614.9	$ 518.2

Property, Plant, and Equipment - Schedule of Property, Plant, and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	$ 7,734.7	$ 6,886.6
Accumulated depreciation and amortization	(2,614.3)	(2,286.9)
Property, plant, and equipment, net	5,120.4	4,599.7
Building and improvements
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	3,105.9	2,573.2
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	174.4	154.5
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	1,543.7	1,494.5
Computer equipment and software
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	522.0	450.8
Furniture, office equipment, and other
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	219.7	203.8
Land
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	278.8	288.2
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	$ 1,890.2	$ 1,721.6

Inventories

12 Months Ended

Dec. 31, 2025

Inventory Disclosure [Abstract]

Inventories

Inventories consist of the following:


	As of December 31,
(In millions)	2025		2024
Raw materials	$	641.5	$	879.5
Work-in-process	1,641.6		1,342.3
Finished goods	190.2		139.8
Deferred costs	727.5		725.7
	$	3,200.8	$	3,087.3

Deferred costs represent the costs of product manufactured and shipped to the Company's collaborators for which recognition of revenue has been deferred. For the years ended December 31, 2025, 2024, and 2023, Cost of goods sold included inventory write-offs and reserves of $172.9 million, $126.3 million, and $102.3 million, respectively.

Debt - Narrative (Details) - USD ($)	12 Months Ended
Debt - Narrative (Details) - USD ($)	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Line of credit \| Senior unsecured revolving credit facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 750,000,000
Line of credit facility, expiration period	5 years
Line of credit facility, increase limit	$ 500,000,000
Borrowings outstanding	0
Line of credit \| Letters of credit
Debt Instrument [Line Items]
Maximum borrowing capacity	50,000,000
Senior unsecured notes
Debt Instrument [Line Items]
Interest expense	$ 44,400,000	$ 44,400,000	$ 44,400,000

Accrued Expenses and Other Current Liabilities

12 Months Ended

Dec. 31, 2025

Payables and Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consist of the following:


	As of December 31,
(In millions)	2025		2024
Accrued payroll and related costs	$	773.0	$	640.9
Accrued clinical expenses	357.2		315.7
Accrued sales-related costs	875.6		786.2
Income tax-related costs	351.3		213.2
Other accrued expenses and liabilities	519.3		571.1
	$	2,876.4	$	2,527.1

Collaboration, License, and Other Agreements

12 Months Ended

Dec. 31, 2025

Revenue from Contract with Customer [Abstract]

Collaboration, License, and Other Agreements

a. Sanofi

The Company is party to a global, strategic collaboration with Sanofi to research, develop, and commercialize fully human monoclonal antibodies, which currently consists of Dupixent® (dupilumab), Kevzara® (sarilumab), and itepekimab.

Sanofi is generally responsible for funding 80% to 100% of agreed-upon development expenses as incurred. The Company is obligated to reimburse Sanofi for 30% to 50% of development expenses that were funded by Sanofi (i.e., "development balance") based on the Company's share of collaboration profits. The Company is required to apply 20% of its share of profits from the collaboration each calendar quarter to reimburse Sanofi for these development expenses. The Company's contingent reimbursement obligation to Sanofi in connection with the development balance was approximately $595 million as of December 31, 2025.

Sanofi leads commercialization activities for products under the collaboration, subject to the Company's right to co-commercialize such products. The Company co-commercializes Dupixent in the United States and in certain countries outside the United States. The Company supplies certain commercial bulk product to Sanofi. The parties equally share profits from sales within the United States. The parties share profits outside the United States on a sliding scale based on sales starting at 65% (Sanofi)/35% (Regeneron) and ending at 55% (Sanofi)/45% (Regeneron).

In addition to profit sharing, the Company was entitled to receive sales milestone payments from Sanofi. During the year ended December 31, 2023, the Company earned the final $50.0 million sales-based milestone from Sanofi upon aggregate annual sales of antibodies outside the United States exceeding $3.0 billion on a rolling twelve-month basis.

Amounts recognized in the Company's Statements of Operations in connection with its Sanofi collaboration are as follows:


	Statement of Operations Classification	Year Ended December 31,
(In millions)		2025		2024		2023
Regeneron's share of profits	Collaboration revenue	$	5,241.6	$	3,923.5	$	3,136.5
Sales-based milestones earned	Collaboration revenue	$	—	$	—	$	50.0
Reimbursement for manufacturing of commercial supplies	Collaboration revenue	$	642.4	$	607.9	$	613.0
Regeneron's obligation for its share of Sanofi R&D expenses, net of reimbursement of R&D expenses	(R&D expense)	$	(69.5)	$	(46.8)	$	(83.7)
Reimbursement of commercialization-related expenses	Reduction of SG&A expense	$	729.3	$	655.4	$	534.4

The following table summarizes contract balances in connection with the Company's Sanofi collaboration:


	As of December 31,
(In millions)	2025		2024
Accounts receivable, net	$	1,610.6	$	1,216.2
Deferred revenue	$	442.3	$	571.7

b. Bayer

The Company is party to a license and collaboration agreement with Bayer for the global development and commercialization of EYLEA 8 mg (aflibercept 8 mg) and EYLEA (aflibercept) outside the United States. The parties generally share equally agreed-upon development expenses as incurred. The Company is also obligated to use commercially reasonable efforts to supply clinical and commercial bulk product to Bayer.

Bayer is responsible for commercialization activities outside the United States, and the companies share equally in profits from such sales. Within the United States, the Company is responsible for commercialization and retains profits from such sales. The Company is obligated to reimburse Bayer out of the Company's share of the collaboration profits for 50% of the agreed-upon development expenses that Bayer has incurred in accordance with a formula based on the amount of development expenses that Bayer has incurred and the Company's share of the collaboration profits, or at a faster rate at the Company's option; the Company's contingent reimbursement obligation to Bayer was approximately $296 million as of December 31, 2025.

Amounts recognized in the Company's Statements of Operations in connection with its Bayer collaboration are as follows:


	Statement of Operations Classification	Year Ended December 31,
(In millions)		2025		2024		2023
Regeneron's share of profits	Collaboration revenue	$	1,282.7	$	1,403.3	$	1,376.4
Reimbursement for manufacturing of commercial supplies	Collaboration revenue	$	139.7	$	95.7	$	111.1
Regeneron's obligation for its share of Bayer R&D expenses, net of reimbursement of R&D expenses	(R&D expense)	$	(20.0)	$	(48.5)	$	(44.0)

The following table summarizes contract balances in connection with the Company's Bayer collaboration:


	As of December 31,
(In millions)	2025		2024
Accounts receivable, net	$	287.6	$	349.9
Deferred revenue	$	295.7	$	216.3

c. Other

In addition to the collaboration and license agreements discussed above, the Company has collaboration and license agreements that are not individually significant to its operating results or financial condition at this time. Pursuant to the terms of those agreements, the Company may (i) incur, and/or get reimbursed for, research and development expenses, and/or (ii) be required to pay, and/or may receive, additional amounts contingent upon the occurrence of various future events (e.g., upon the achievement of development and commercial milestones), which in the aggregate could be significant.

In January 2026, the Company's collaboration agreement with Tessera Therapeutics, Inc. to develop and commercialize TSRA-196 (Tessera's investigational program for the treatment of alpha-1 antitrypsin deficiency ("AATD")) became effective. Under the terms of the agreement, the Company made aggregate payments of $150.0 million in January 2026, consisting of an up-front payment and the purchase of Tessera preferred stock. The portion related to the up-front payment will be recorded to Acquired IPR&D expense in the first quarter of 2026.

Acquired IPR&D Expenses

During the year ended December 31, 2025, the Company recorded to Acquired IPR&D expense an $80.0 million up-front payment in connection with its license agreement with Hansoh Pharmaceuticals Group Company Limited to acquire development and commercial rights outside mainland China, Hong Kong, and Macau for HS-20094 (a dual GLP-1/GIP receptor agonist currently in Phase 3 clinical development in China).

During the year ended December 31, 2024, the Company recorded to Acquired IPR&D expense a $45.0 million development milestone in connection with its collaboration agreement with Sonoma Biotherapeutics, Inc.

During the year ended December 31, 2023, the Company recorded to Acquired IPR&D expense a $100.0 million development milestone in connection with its collaboration agreement with Alnylam Pharmaceuticals, Inc., a $45.0 million up-front payment in connection with its collaboration agreement with Sonoma, and a $30.0 million extension payment under its collaboration agreement with Intellia Therapeutics, Inc.

Royalties

The Company has also in-licensed patent and/or technology pursuant to agreements which contain provisions that require the Company to pay royalties, as defined, at rates that range from 0.5% to 12.5%, in the event the Company sells or licenses any proprietary products developed under the respective agreements. For the years ended December 31, 2025, 2024, and 2023, the Company recorded royalty expense (net of reimbursements from collaborators, as applicable) of $81.3 million, $82.9 million, and $117.6 million, respectively, based on product sales under various licensing agreements.

Legal Matters	12 Months Ended
Legal Matters	Dec. 31, 2025
Commitments and Contingencies Disclosure [Abstract]
Legal Matters	Legal Matters From time to time, the Company is a party to legal proceedings in the course of the Company's business. The outcome of any such proceedings, regardless of the merits, is inherently uncertain. If the Company is unable to prevail in one or more of such proceedings, its consolidated financial position, results of operations, and future cash flows may be materially adversely impacted. Costs associated with the Company's involvement in legal proceedings are expensed as incurred. The Company recognizes gain contingencies associated with such proceedings when the award or recovery is realized or realizable and loss contingencies when it is probable that a liability will be incurred and the amount of loss can be reasonably estimated. As of December 31, 2025 and 2024, the Company's accruals for loss contingencies were not material. There are certain loss contingencies that the Company deems reasonably possible for which the possible loss or range of possible loss is not estimable at this time. a. Proceedings Relating to EYLEA (aflibercept) Injection (1) United States As described in greater detail below, the Company has filed several patent infringement lawsuits against various parties in the United States alleging infringement of certain Company patents pertaining to EYLEA, and certain of these patents have also been subject to post-grant proceedings before the United States Patent and Trademark Office ("USPTO"). (i) U.S. Patent Litigation In 2025, the Company entered into settlement agreements resulting in the dismissal of the previously disclosed patent infringement lawsuits before the United States District Court for the Northern District of West Virginia against Mylan Pharmaceuticals Inc. ("Mylan") and Biocon Biologics Inc. ("Biocon"); Celltrion, Inc. ("Celltrion"); Formycon AG ("Formycon"); and Sandoz Inc. ("Sandoz"). The lawsuits each alleged infringement of certain Company patents, including the Company's U.S. Patent No. 11,084,865 (the "'865 Patent"). Pursuant to the settlement agreements, these parties are precluded from launching their respective aflibercept 2 mg biosimilars until the second half of 2026 (Mylan/Biocon), fourth quarter of 2026 (Sandoz and Formycon), and December 31, 2026 (Celltrion). On January 10, 2024, the Company filed a patent infringement lawsuit against Amgen Inc. ("Amgen") in the United States District Court for the Central District of California (subsequently transferred to the United States District Court for the Northern District of West Virginia) alleging that Amgen's filing for FDA approval of an aflibercept 2 mg biosimilar infringed certain Company patents. On September 23, 2024, the court denied the Company's motion for a preliminary injunction, which decision was affirmed by the Federal Circuit on March 14, 2025. On June 17, 2025, the Company filed an additional patent infringement lawsuit against Amgen in the United States District Court for the Central District of California alleging that Amgen's continued commercialization of its aflibercept 2 mg biosimilar infringes the Company's U.S. Patent No. 12,331,099. On September 12, 2025, Amgen filed its answer and counterclaims alleging, among other things, that the Company obtained numerous patents fraudulently, rendering them unenforceable, and that obtaining and enforcing certain Company patents violated Section 2 of the Sherman Antitrust Act of 1890, as amended (the "Sherman Antitrust Act"). On November 12, 2025, the Company filed a motion to dismiss Amgen's affirmative defenses and counterclaims. (ii) Post-Grant Proceedings Before the USPTO On November 20, 2024, November 29, 2024, and January 15, 2025, Samsung Bioepis, Formycon, and Celltrion, respectively, filed inter partes review ("IPR") petitions in the USPTO against the '865 Patent, each seeking a declaration that the '865 Patent is invalid. On June 6, 2025, the USPTO denied institution of Samsung and Formycon's respective IPR petitions, and on June 25, 2025, the USPTO denied institution of Celltrion's IPR petition. On July 14, 2025, Fresenius Kabi SwissBioSim GmbH filed IPR petitions in the USPTO against the '865 Patent and U.S. Patent No. 10,828,345 (the "'345 Patent"), seeking a declaration that the '865 Patent and '345 Patent are invalid. On November 20, 2025, and January 6, 2026, the USPTO denied institution of Fresenius' IPR petitions against the '865 Patent and the '345 Patent, respectively. (2) Outside the United States As described in greater detail below, the Company has filed patent infringement lawsuits against various parties in several jurisdictions outside the United States alleging infringement of certain Company patents pertaining to EYLEA, and certain of these patents have also been subject to post-grant proceedings before the European Patent Office (the "EPO") and/or other comparable foreign authorities. (i) Multijurisdictional Settlements Biocon. On December 13, 2025, the Company and Bayer entered into a settlement agreement with Biocon and its affiliated entities in respect of all jurisdictions outside the United States with the exception of Canada (separately settled in March 2024, as previously disclosed). Pursuant to the settlement agreement, all pending judicial and administrative proceedings related to Biocon's aflibercept 2 mg biosimilar product has been dismissed and Biocon is permitted to launch such biosimilar product in the United Kingdom in January 2026 and in the rest of the jurisdictions covered by the settlement in March 2026 or, in each case, earlier in certain circumstances. Celltrion. On January 21, 2026, the Company and Bayer entered into a settlement agreement with Celltrion in respect of all jurisdictions outside the United States with the exceptions of Canada (separately settled in July 2024, as previously disclosed) and Singapore (separately settled in November 2025). Pursuant to the settlement agreement, all pending judicial and administrative proceedings related to Celltrion's aflibercept 2 mg biosimilar product, including the previously disclosed litigation in South Korea, has or will be dismissed and Celltrion is permitted to launch such biosimilar product in South Korea and the United Kingdom in January 2026 and in the rest of the jurisdictions covered by the settlement in the second quarter of 2026, or earlier in certain circumstances. Alvotech. On January 28, 2026, the Company and Bayer entered into a settlement agreement with Alvotech HF ("Alvotech") in respect of all jurisdictions outside the United States. Pursuant to the settlement agreement, all pending judicial and administrative proceedings related to Alvotech's aflibercept 2 mg biosimilar product, including the litigation in Germany discussed below, has or will be dismissed and Alvotech is permitted to launch such biosimilar product in Canada, the United Kingdom, and Japan in January 2026 (November 2026 in the case of the DME indication in Japan) and in the rest of the jurisdictions covered by the settlement in May 2026. Samsung Bioepis. On January 29, 2026, the Company and Bayer entered into a settlement agreement with Samsung Bioepis in respect of all jurisdictions outside the United States with the exception of Canada (separately settled in October 2024, as previously disclosed). Pursuant to the settlement agreement, all pending judicial and administrative proceedings related to Samsung Bioepis' aflibercept 2 mg biosimilar product, including the litigation in the United Kingdom, Germany, the Netherlands, and South Korea discussed below, has or will be dismissed and Samsung Bioepis is permitted to maintain its biosimilar on the market in South Korea and launch such biosimilar product in the United Kingdom in January 2026, the rest of Europe in April 2026, and the rest of the jurisdictions covered by the settlement in May 2026. (ii) Europe (I) EPO Post-Grant Proceedings Various parties, including Amgen and other, anonymous parties, are seeking revocation of the Company's European Patent Nos. 2,944,306 (the "'306 Patent"), 3,716,992 (the "'992 Patent"), and 3,384,049 (the "'049 Patent") before the Opposition Division ("OD") of the EPO. On November 26, 2024, following an oral hearing, the OD announced its decision to revoke the '306 Patent. On March 11, 2025, the Company appealed the OD's decision, and an oral hearing concerning the appeal has been scheduled for October 2026. On October 22, 2025, following an oral hearing, the OD upheld the validity of the '992 Patent's claims in amended form. An oral hearing concerning the '049 Patent has been scheduled for April 2026. (II) Country-Specific Proceedings The Company is also party to proceedings against various parties, including Samsung Bioepis, Formycon, Amgen, Alvotech, Celltrion, Sandoz, and/or their affiliated entities, before several European national courts (including those in Belgium, France, Germany, Italy, the Netherlands, and the United Kingdom). In certain of these proceedings, the counterparties are seeking revocation of one or more Company patents pertaining to EYLEA, including the '306 Patent, the '992 Patent, the Company's European Patent No. 2,364,691 (the "'691 Patent"), and the Company's European Patent No. 1,183,353 (as extended by Supplementary Protection Certificate 2013C/029), and/or a declaration that their respective aflibercept 2 mg biosimilars would not infringe these patents, and in the same or other proceedings, the Company is alleging infringement of such patents. As noted above, the Company and Bayer recently entered into settlement agreements with Samsung Bioepis, Alvotech, and Celltrion, pursuant to which the proceedings discussed below have been or will be dismissed with respect to these parties. Key recent developments in the proceedings set forth below are as follows: •United Kingdom: ◦Following trials held in June 2025, the High Court of England and Wales issued a decision in October 2025 that found that Formycon and Samsung Bioepis's aflibercept 2 mg biosimilar products do not infringe the '691 and '306 Patents; upheld the '691 Patent as valid; and invalidated the '306 Patent. In December 2025, the Company appealed this decision. ◦Proceedings in the United Kingdom concerning the '992 Patent are stayed pending resolution of the EPO proceedings concerning this patent. •Germany: ◦Following a June 2025 trial concerning the revocation proceeding brought by Samsung Bioepis, the German Federal Patent Court upheld the '691 Patent as valid. ◦In October 2025, the Munich Regional Court issued a decision that found that Formycon's aflibercept biosimilar product infringes the '691 Patent and granted the Company's motion for a permanent injunction, enjoining Formycon from selling its aflibercept 2 mg biosimilar in Germany and several other EU countries (including Spain and the Netherlands) until the expiration of the '691 Patent. ◦In January 2026, the Munich Regional Court issued decisions that found that each of Alvotech's, Celltrion's, and Sandoz's aflibercept 2 mg biosimilar products infringes the '691 Patent and granted the Company's motions for preliminary injunctions, enjoining such parties from selling their aflibercept 2 mg biosimilars in Germany and, in the case of Alvotech, also several other EU countries (including France, Spain, Italy, and the Netherlands). •Netherlands: ◦Following a trial held in July 2025, the District Court of the Hague issued a decision in October 2025 that upheld the '691 and '306 Patents as valid; found that Samsung Bioepis's aflibercept 2 mg biosimilar product infringes the '691 and '306 Patents; and granted the Company's request for a permanent injunction, enjoining Samsung Bioepis from selling its aflibercept 2 mg biosimilar in the Netherlands until the expiration of the '691 and '306 Patents. (iii) Canada In 2025, the Company, Bayer Inc., and Bayer Healthcare LLC entered into settlement agreements resulting in the dismissal of the previously disclosed patent infringement lawsuits and/or invalidation proceedings before the Federal Court of Canada against Amgen Canada Inc. ("Amgen Canada") and Sandoz Canada Inc. Pursuant to the settlement agreements, the Company, Bayer Inc., and Bayer Healthcare LLC are no longer seeking a declaration that Amgen Canada's or Sandoz's respective aflibercept 2 mg biosimilar products infringe the asserted Company patents. (iv) South Korea As noted above, the Company and Bayer recently entered into settlement agreements with Samsung Bioepis and Celltrion, pursuant to which the proceedings discussed below have been or will be dismissed with respect to these parties. On December 13, 2022, Samsung Bioepis initiated invalidation proceedings before the Intellectual Property Trial and Appeal Board of the Korean Intellectual Property Office ("KIPO") against the Company's Korean Patent No. 1406811 (the "'811 Patent"), seeking revocation of the '811 Patent in its entirety. On October 23, 2024, the KIPO maintained the '811 Patent as valid. On October 30, 2025, the IP High Court overturned the decision of the KIPO and invalidated the '811 Patent; the Company has appealed that decision. The Company and, as applicable, Bayer Consumer Care AG, have also filed patent infringement lawsuits in the Seoul Central District Court against various parties including Samsung Bioepis and its parent company Samsung Biologics Co., Ltd. (collectively, "Samsung"), Sam Chun Dang Pharm. Co., Ltd. and OPTUS Pharmaceutical Co., Ltd., and Celltrion. These lawsuits seek damages and/or injunctive relief and allege that the making, constructing, using, or selling of an aflibercept 2 mg biosimilar by the relevant defendant(s) would infringe one or more claims of the '811 Patent and/or the Company's Korean Patent Nos. 659477 (the "'477 Patent") and 2519234 (the "'234 Patent"). On February 7, 2025, the Seoul Central District Court granted the Company's preliminary injunction request against Samsung on the basis of the '811 Patent. Also on February 7, 2025, the Seoul Central District Court denied Regeneron's preliminary injunction request against Celltrion. In light of the decision of the IP High Court discussed above, on December 3, 2025, the Seoul High Court issued a decision lifting the preliminary injunction against Samsung. (v) Australia On June 4, 2025, the Company, Bayer Consumer Care AG, and Bayer Australia filed a patent infringement lawsuit against Sandoz Pty Ltd. and a request for a preliminary injunction in the Federal Court of Australia alleging that the importing, selling, supplying, or otherwise disposing of an aflibercept 2 mg biosimilar would infringe one or more claims of the Company's Australian Patent No. 2012205599. On September 3, 2025, the court denied the Company's request for a preliminary injunction. On November 26, 2025, the parties entered into a settlement agreement, pursuant to which this lawsuit has been dismissed. (vi) Japan On October 10, 2025, the Company filed a patent infringement lawsuit in the Osaka District Court against Fuji Pharma Co., Ltd. alleging that the making, constructing, using, or selling of an aflibercept 2 mg biosimilar by the defendant would infringe one or more claims of the Company's Japanese Patent No. 7,733,706. b. Proceedings Relating to EYLEA (aflibercept) Injection Pre-filled Syringe On July 17, 2020, the Company filed an antitrust lawsuit (as amended on January 25, 2021) against Novartis Pharma AG, Novartis Pharmaceuticals Corporation, and Novartis Technology LLC (collectively, "Novartis") and Vetter Pharma International GmbH in the United States District Court for the Southern District of New York seeking a judgment that the defendants' conduct relating to Novartis's attempt to assert its U.S. Patent No. 9,220,631 against Regeneron in 2020 violated Sections 1 and 2 of the Sherman Antitrust Act, and constituted tortious interference with contract. The Company is also seeking injunctive relief and treble damages. On September 21, 2021, this lawsuit was transferred to the Northern District of New York. On June 10, 2022, the Company filed an appeal of the District Court's decision to dismiss the amended complaint with the U.S. Court of Appeals for the Second Circuit (the "Second Circuit"). On March 18, 2024, the Second Circuit reversed the District Court's decision to dismiss the amended complaint and remanded the lawsuit to the District Court for further proceedings consistent with the Second Circuit's opinion. On November 19, 2024, the Company moved to transfer the lawsuit back to the Southern District of New York, which motion was granted on December 5, 2024. c. Proceedings Relating to Praluent (alirocumab) Injection On May 27, 2022, the Company filed a lawsuit against Amgen in the United States District Court for the District of Delaware, alleging that, beginning in 2020, Amgen engaged in an anticompetitive bundling scheme which was designed to exclude Praluent from the market in violation of federal and state laws. The lawsuit seeks damages for harm caused by the alleged scheme, as well as injunctive relief restraining Amgen from continuing its alleged anticompetitive conduct. A trial was held in May 2025. On May 15, 2025, the jury reached a verdict in Regeneron's favor on nine of the ten counts submitted to it and awarded Regeneron $135.6 million in compensatory damages and $271.2 million in punitive damages. On June 20, 2025, Amgen filed a post-trial motion for judgment as a matter of law or, in the alternative, for a new trial. Also on June 20, 2025, the Company filed a post-trial motion for (i) permanent injunctive relief, (ii) a constructive trust, and (iii) prejudgment interest. An oral hearing on Amgen's and Regeneron's respective post-trial motions was held on August 27, 2025. d. Department of Justice Matters On June 24, 2020, the U.S. Attorney's Office for the District of Massachusetts filed a civil complaint in the U.S. District Court for the District of Massachusetts alleging violations of the federal Anti-Kickback Statute and asserting causes of action under the federal False Claims Act and state law (the "June 2020 Civil Complaint") relating to the Company's support of 501(c)(3) organizations that provide financial assistance to patients. On September 27, 2023, the court (i) denied in part and granted in part the Company's motion for summary judgment and (ii) denied in its entirety the motion for partial summary judgment filed by the U.S. Attorney's Office for the District of Massachusetts. On October 25, 2023, the court certified for interlocutory appeal a portion of the court's September 27, 2023 order that addressed the causation standard applicable to the alleged violations of the federal Anti-Kickback Statute and federal False Claims Act. On February 18, 2025, the U.S. Court of Appeals for the First Circuit affirmed the portion of the court's September 27, 2023 order that had been certified for interlocutory appeal. On October 1, 2025, the U.S. Attorney's Office for the District of Massachusetts filed a second motion for partial summary judgment. On June 3, 2021, the United States District Court for the Central District of California unsealed a qui tam complaint (as amended on October 29, 2021) filed against the Company, Regeneron Healthcare Solutions, Inc., and Sanofi-Aventis U.S. LLC by two qui tam plaintiffs (known as relators) purportedly on behalf of the United States and various states (the "State Plaintiffs"). The amended complaint alleges violations of the federal Anti-Kickback Statute and asserts causes of action under the federal False Claims Act and state law relating to allegedly unlawful remuneration and assistance provided to prescribers. Also on June 3, 2021, the United States and the State Plaintiffs notified the court of their decision to decline to intervene in the case. On January 14, 2022, the Company filed a motion to dismiss the amended complaint in its entirety. On July 25, 2023, the court granted in part and denied in part the Company's motion to dismiss. On September 1, 2023, the Company filed a second motion to dismiss the amended complaint or, in the alternative, a motion for judgment on the pleadings. On July 31, 2024 and August 15, 2024, respectively, the District Court granted the Company's second motion to dismiss the amended complaint with respect to the remaining causes of action under federal law and declined to exercise supplemental jurisdiction over the remaining causes of action under state law. On August 26, 2024, the qui tam plaintiffs filed a notice of appeal. Oral argument on the appeal was held on November 18, 2025. In June 2021, the Company received a civil investigative demand ("CID") from the U.S. Department of Justice pursuant to the federal False Claims Act relating to, among other things, alleged inflated reimbursement rates for EYLEA by excluding applicable discounts, rebates, and benefits from the average sales price reported to the Centers for Medicare & Medicaid Services. On March 28, 2024, the U.S. District Court for the District of Massachusetts unsealed a qui tam complaint against the Company and others by two qui tam plaintiffs, purportedly on behalf of the United States and various states and municipalities, asserting causes of action under the federal False Claims Act and state and local laws, and alleging violations of the federal Anti-Kickback statute related to, among other things, the alleged conduct described above. Also on March 28, 2024, the U.S. Department of Justice and the U.S. Attorney's Office for the District of Massachusetts filed a civil complaint in partial intervention (the "March 2024 Civil Complaint") of the qui tam action, in the same court, asserting causes of action under the federal False Claims Act and a claim for unjust enrichment related to the alleged conduct described above. On June 25, 2024, the States of Colorado, Georgia, Michigan, North Carolina, Texas, and Washington filed a civil complaint in partial intervention (the "June 2024 Civil Complaint") in the same court asserting causes of action under various state laws related to the same alleged conduct. On April 29, 2025, the court denied the Company's motion to dismiss the March 2024 Civil Complaint and the June 2024 Civil Complaint. On June 18, 2025, the States of Maine, Nebraska, Ohio, Oregon, and Wyoming intervened in the action and filed a consolidated complaint asserting causes of action under their respective state laws. e. Proceedings Initiated by Other Payors The Company is party to several lawsuits relating to the conduct alleged in the June 2020 Civil Complaint discussed under "d. Department of Justice Matters" above. These lawsuits were filed by UnitedHealthcare Insurance Company and United Healthcare Services, Inc. (collectively, "UHC") and Humana Inc. ("Humana") in the United States District Court for the Southern District of New York on December 17, 2020 and July 22, 2021, respectively; and by Blue Cross and Blue Shield of Massachusetts, Inc. and Blue Cross and Blue Shield of Massachusetts HMO Blue, Inc. (collectively, "BCBS"), Medical Mutual of Ohio ("MMO"), Horizon Healthcare Services, Inc. d/b/a Horizon Blue Cross Blue Shield of New Jersey ("Horizon"), and Local 464A United Food and Commercial Workers Union Welfare Service Benefit Fund ("Local 464A") in the U.S. District Court for the District of Massachusetts on December 20, 2021, February 23, 2022, April 4, 2022, and June 17, 2022, respectively. These lawsuits allege causes of action under state law and the federal Racketeer Influenced and Corrupt Organizations Act ("RICO") and seek monetary damages and equitable relief. The MMO and Local 464A lawsuits are putative class action lawsuits. On December 29, 2021, the lawsuits filed by UHC and Humana were stayed by the United States District Court for the Southern District of New York pending resolution of the proceedings before the U.S. District Court for the District of Massachusetts concerning the allegations in the June 2020 Civil Complaint. On September 27, 2022, the lawsuits filed by BCBS, MMO, and Horizon were stayed by the U.S. District Court for the District of Massachusetts pending resolution of the proceedings before the same court concerning the allegations in the June 2020 Civil Complaint; and, in light of these stays, the parties to the Local 464A action have also agreed to stay that matter. On June 24, 2024, a group of plaintiffs purporting to be assignees of claims by various Medicare Advantage plans and related entities filed a putative class action complaint in the U.S. District Court for the District of Columbia on behalf of Medicare Advantage plans and other payors. The lawsuit relates to the conduct alleged in the June 2020 Civil Complaint, March 2024 Civil Complaint, and June 2024 Civil Complaint discussed under "d. Department of Justice Matters" above. The lawsuit alleges causes of action under state law and RICO and seeks monetary damages and equitable relief. On October 22, 2024, the Company filed a motion to transfer the proceedings to the U.S. District Court for the District of Massachusetts or, in the alternative, to stay the proceedings or dismiss the proceedings. On January 28, 2025, pursuant to a stipulation among the parties, the proceedings were transferred to the U.S. District Court for the District of Massachusetts. On February 1, 2025, the parties jointly filed a stipulation to stay the action pending resolution of the proceedings before the same court concerning the allegations in the June 2020 Civil Complaint. f. Shareholder Derivative Complaint – Department of Justice June 2020 Civil Complaint Matters On June 29, 2021, an alleged shareholder filed a shareholder derivative complaint in the New York Supreme Court, naming the then-current and certain former members of the Company's board of directors and certain then-current and former executive officers of the Company as defendants and Regeneron as a nominal defendant. The complaint asserts that the individual defendants breached their fiduciary duties in relation to the allegations in the June 2020 Civil Complaint discussed under "d. Department of Justice Matters" above. The complaint seeks an award of damages allegedly sustained by the Company; an order requiring Regeneron to take all necessary actions to reform and improve its corporate governance and internal procedures; disgorgement from the individual defendants of all profits and benefits obtained by them resulting from their sales of Regeneron stock; and costs and disbursements of the action, including attorneys' fees. On July 28, 2021, the defendants filed a notice of removal, removing the case from the New York Supreme Court to the U.S. District Court for the Southern District of New York. On September 23, 2021, the plaintiff moved to remand the case to the New York Supreme Court. Also on September 23, 2021, the individual defendants moved to dismiss the complaint in its entirety. On December 19, 2022, the U.S. District Court for the Southern District of New York denied the plaintiff's motion to remand the case and granted a motion to stay the case pending resolution of the proceedings before the U.S. District Court for the District of Massachusetts concerning the allegations in the June 2020 Civil Complaint. As a result of the stay, the court also terminated the Company's motion to dismiss the complaint without prejudice. The Company can therefore renew the motion to dismiss upon conclusion of the stay. g. Shareholder Derivative Complaints – Department of Justice March 2024 Civil Complaint Matters In 2025, various purported shareholders of the Company filed several shareholder derivative complaints in the U.S. District Court for the Southern District of New York or the Supreme Court of the State of New York against members of the Company's board of directors and certain current and former executive officers of the Company as defendants and Regeneron as a nominal defendant. The complaints allege that the individual defendants, among other things, breached their fiduciary duties to the Company by failing to properly manage and oversee the Company in connection with the conduct alleged in the March 2024 Civil Complaint discussed under "d. Department of Justice Matters" above, and one lawsuit also alleges a breach of fiduciary duty relating to the conduct alleged in the second amended putative class action civil complaint discussed under "i. Class Action Civil Complaint" below. The complaints also allege that the individual defendants breached the federal securities laws, wasted corporate assets, and unjustly enriched themselves at the expense of the Company. The complaints seek, among other things, an award of damages allegedly sustained by the Company as a result of the alleged misconduct of the individual defendants; an order requiring the individual defendants to take all necessary actions to reform and improve the Company's corporate governance and internal procedures; and costs and disbursements of the applicable action, including attorneys' fees. Certain of these shareholder derivative complaints have been consolidated by the U.S. District Court for the Southern District of New York. The shareholder derivative complaints filed in the Supreme Court of the State of New York have been removed to the U.S. District Court for the Southern District of New York and motions to remand are pending. h. Shareholder Derivative Complaint – Director Compensation On July 22, 2025, an alleged shareholder filed a shareholder derivative complaint in the New York Supreme Court, naming the current non-employee members of our board of directors, and the co-Chairs of our board of directors (who also serve as our President and Chief Executive Officer and our President and Chief Scientific Officer, respectively) as defendants and Regeneron as a nominal defendant. The complaint asserts that the individual defendants breached their fiduciary duties and/or were unjustly enriched when they approved and/or received allegedly excessive non-employee director compensation in 2024 and 2025, and that this allegedly excessive compensation was a waste of corporate assets. The complaint seeks damages in favor of Regeneron for the alleged breaches of fiduciary duties, unjust enrichment, and waste of corporate assets; improvements to Regeneron's corporate governance and internal procedures; equitable relief, including restitution from the individual defendants; and award of the costs of the action, including attorneys' fees. On September 25, 2025, the Company filed a motion to dismiss the complaint. i. Class Action Civil Complaint On January 7, 2025 (as amended on September 8, 2025 and October 30, 2025), a purported shareholder filed a putative class action civil complaint, on behalf of himself and all others similarly situated, in the U.S. District Court for the Southern District of New York against the Company and certain current and former executive officers of the Company. The second amended complaint asserts violations of federal securities laws in connection with statements or disclosures purportedly related to the conduct alleged in the March 2024 Civil Complaint discussed under "d. Department of Justice Matters" above as well as allegations relating to the launch of EYLEA HD. On July 10, 2025, the court appointed a lead plaintiff and lead counsel for the action. On November 17, 2025, the Company filed a motion to dismiss the second amended complaint. j. Sanofi Litigation On November 18, 2024, the Company filed a lawsuit (as amended on December 20, 2024) in the United States District Court for the Southern District of New York against Sanofi and certain of its affiliated entities. The lawsuit alleges that the defendants breached certain provisions of the parties' Amended and Restated License and Collaboration Agreement, dated as of November 10, 2009 (as amended, the "Collaboration Agreement"), concerning Sanofi's obligation to provide Regeneron with full access to material information relating to the commercialization of Dupixent or other products commercialized pursuant to the Collaboration Agreement and Regeneron's audit rights under the Collaboration Agreement. The lawsuit seeks a declaratory judgment, injunctive relief, damages, and other relief. On July 3, 2025, Sanofi filed a motion to dismiss the complaint.

Long-Term Incentive Plans - Summary of activity related to restricted stock awards (Details) - Restricted stock awards and restricted stock units shares in Millions	12 Months Ended
	Dec. 31, 2025 $ / shares shares
Number of Shares/Units (In millions)
Beginning balance (in shares) \| shares	2.5
Granted (in shares) \| shares	1.4
Vested (in shares) \| shares	(0.7)
Forfeited (in shares) \| shares	(0.1)
Ending balance (in shares) \| shares	3.1
Weighted-Average Grant Date Fair Value
Beginning balance (in dollars of shares) \| $ / shares	$ 760.35
Granted (in dollars of shares) \| $ / shares	718.94
Vested (in dollars of shares) \| $ / shares	734.49
Forfeited (in dollars of shares) \| $ / shares	753.77
Ending balance (in dollars of shares) \| $ / shares	$ 748.08

Collaboration, License, and Other Agreements - Schedule of Accounts Receivable and Deferred Revenue Information, Antibody Collaboration (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Disaggregation of Revenue [Line Items]
Accounts receivable, net	$ 5,741.1	$ 6,211.9
Sanofi Collaboration Agreement, Antibody
Disaggregation of Revenue [Line Items]
Accounts receivable, net	1,610.6	1,216.2
Deferred revenue	$ 442.3	$ 571.7

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Name Accounting Standards Codification
-Section 50
-Paragraph 7
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Accrued Expenses and Other Current Liabilities (Tables)

12 Months Ended

Dec. 31, 2025

Payables and Accruals [Abstract]

Schedule of accrued expenses and other current liabilities

Accrued expenses and other current liabilities consist of the following:


	As of December 31,
(In millions)	2025		2024
Accrued payroll and related costs	$	773.0	$	640.9
Accrued clinical expenses	357.2		315.7
Accrued sales-related costs	875.6		786.2
Income tax-related costs	351.3		213.2
Other accrued expenses and liabilities	519.3		571.1
	$	2,876.4	$	2,527.1

Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned not readily marketable	$ 334.0	$ 159.8
Net unrealized gains (losses) recognized on investments still held as of period end date	(10.6)	117.7	$ (241.6)
Level 3 \| Measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	147.5	52.0
Level 2 \| Measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 1,576.0	$ 1,484.0

- Definition

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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-Publisher FASB
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+ Details

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

+ Details

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Revenues:
Revenue from contract with customer	$ 14,342.9	$ 14,202.0	$ 13,117.2
Expenses:
Research and development	5,850.2	5,132.0	4,439.0
Acquired in-process research and development	124.1	101.0	186.1
Selling, general, and administrative	2,700.0	2,954.4	2,631.3
Other operating (income) expense, net	(10.0)	53.4	(2.1)
Total expenses	10,765.0	10,211.3	9,070.1
Income from operations	3,577.9	3,990.7	4,047.1
Other income (expense):
Other income (expense), net	1,696.6	844.4	225.2
Interest expense	(43.8)	(55.2)	(73.0)
Total other income (expense)	1,652.8	789.2	152.2
Income before income taxes	5,230.7	4,779.9	4,199.3
Income tax expense	725.8	367.3	245.7
Net income	$ 4,504.9	$ 4,412.6	$ 3,953.6
Net income per share - basic (in dollars per share)	$ 43.07	$ 40.90	$ 37.05
Net income per share - diluted (in dollars per share)	$ 41.48	$ 38.34	$ 34.77
Weighted average shares outstanding - basic (in shares)	104.6	107.9	106.7
Weighted average shares outstanding - diluted (in shares)	108.6	115.1	113.7
Statements of Comprehensive Income
Net income	$ 4,504.9	$ 4,412.6	$ 3,953.6
Other comprehensive income (loss), net of tax:
Unrealized gain on debt securities	83.0	73.6	158.2
Gain (loss) on foreign currency translation	2.4	(0.6)	(0.3)
Comprehensive income	4,590.3	4,485.6	4,111.5
Net product sales
Revenues:
Revenue from contract with customer	6,309.1	7,629.2	7,078.0
Expenses:
Cost of goods sold and of collaboration and contract manufacturing	1,140.8	1,087.3	932.1
Collaboration revenue
Revenues:
Revenue from contract with customer	7,331.2	6,057.8	5,503.1
Other revenue
Revenues:
Revenue from contract with customer	702.6	515.0	536.1
Cost of collaboration and contract manufacturing
Expenses:
Cost of goods sold and of collaboration and contract manufacturing	$ 959.9	$ 883.2	$ 883.7

Income Taxes - Schedule of effective income tax rate reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Amount
U.S. federal statutory tax rate	$ 1,098,400
Other	4,300
Research and development and orphan drug tax credits	(133,300)
Foreign-derived deduction eligible income	(20,600)
Net CFC tested income ("NCTI"), net of foreign tax credit ("FTC")	(82,700)
Subpart F income, net of FTC	8,300
Changes in unrecognized tax benefits(a)	124,200
Effect of changes in tax laws or rates enacted in the current period	44,500
Stock-based compensation	14,100
Other permanent differences	27,000
Effective tax rate	$ 725,800	$ 367,300	$ 245,700
Percent
U.S. federal statutory tax rate	21.00%	21.00%	21.00%
Statutory tax rate difference between Ireland and United States		(4.00%)	(6.60%)
Other	0.10%
Research and development and orphan drug tax credits	(2.50%)
Foreign-derived deduction eligible income	(0.40%)	(0.80%)	(0.30%)
Net CFC tested income ("NCTI"), net of foreign tax credit ("FTC")	(1.60%)
Subpart F income, net of FTC	0.10%
Changes in unrecognized tax benefits(a)	2.40%
Effect of changes in tax laws or rates enacted in the current period	0.90%
Stock-based compensation	0.30%	(4.90%)	(4.60%)
Other permanent differences	0.50%	(0.10%)	(0.40%)
Effective tax rate	13.90%	7.70%	5.90%
Ireland
Amount
Statutory tax rate difference between Ireland and United States	$ (480,300)
Domestic top-up tax	120,000
Other	$ (5,800)
Percent
Statutory tax rate difference between Ireland and United States	(9.20%)
Domestic top-up tax	2.30%
Other	(0.10%)
Other foreign jurisdictions
Amount
Statutory tax rate difference between Ireland and United States	$ 7,700
Percent
Statutory tax rate difference between Ireland and United States	0.10%

Segment Information - Narrative (Details)	12 Months Ended
Segment Information - Narrative (Details)	Dec. 31, 2025 segment
Segment Reporting [Abstract]
Number of business segments	1

Product Sales (Tables)

12 Months Ended

Dec. 31, 2025

Revenue from Contract with Customer [Abstract]

Schedule of product sales

Net product sales consist of the following:


		Year Ended December 31,
(In millions)		2025		2024		2023
EYLEA HD®	U.S.	$	1,636.9	$	1,201.1	$	165.8
EYLEA®	U.S.	2,747.8		4,767.1		5,719.6
Total EYLEA HD and EYLEA	U.S.	4,384.7		5,968.2		5,885.4
Libtayo®	U.S.	944.7		787.3		538.8
Libtayo	Rest of world	507.5		429.5		324.3
Total Libtayo	Global	1,452.2		1,216.8		863.1
Praluent®	U.S.	262.5		241.7		182.4
Evkeeza®	U.S.	162.2		125.7		77.3
Inmazeb®	U.S.	37.4		76.8		69.8
Other products	Global	10.1		—		—
		$	6,309.1	$	7,629.2	$	7,078.0

Amounts recognized in the Company's Statements of Operations in connection with its Sanofi collaboration are as follows:


	Statement of Operations Classification	Year Ended December 31,
(In millions)		2025		2024		2023
Regeneron's share of profits	Collaboration revenue	$	5,241.6	$	3,923.5	$	3,136.5
Sales-based milestones earned	Collaboration revenue	$	—	$	—	$	50.0
Reimbursement for manufacturing of commercial supplies	Collaboration revenue	$	642.4	$	607.9	$	613.0
Regeneron's obligation for its share of Sanofi R&D expenses, net of reimbursement of R&D expenses	(R&D expense)	$	(69.5)	$	(46.8)	$	(83.7)
Reimbursement of commercialization-related expenses	Reduction of SG&A expense	$	729.3	$	655.4	$	534.4

Amounts recognized in the Company's Statements of Operations in connection with its Bayer collaboration are as follows:


	Statement of Operations Classification	Year Ended December 31,
(In millions)		2025		2024		2023
Regeneron's share of profits	Collaboration revenue	$	1,282.7	$	1,403.3	$	1,376.4
Reimbursement for manufacturing of commercial supplies	Collaboration revenue	$	139.7	$	95.7	$	111.1
Regeneron's obligation for its share of Bayer R&D expenses, net of reimbursement of R&D expenses	(R&D expense)	$	(20.0)	$	(48.5)	$	(44.0)

Schedules of concentration of risk, by risk factor

Sales to each of these customers as a percentage of the Company's total gross product revenue are as follows:


	Year Ended December 31,
	2025		2024		2023
Customer A	50	%	50	%	51	%
Customer B	27	%	24	%	25	%

Sales related deductions activity

The following table summarizes the provisions, and credits/payments, for sales-related deductions:


(In millions)	Rebates, Chargebacks, and Discounts		Distribution- Related Fees		Other Sales- Related Deductions		Total
Balance as of December 31, 2022	$	353.9	$	111.4	$	81.5	$	546.8
Provisions	2,074.5		439.2		155.3		2,669.0
Credits/payments	(1,972.7)		(388.3)		(157.5)		(2,518.5)
Balance as of December 31, 2023	455.7		162.3		79.3		697.3
Provisions	2,447.3		462.7		143.0		3,053.0
Credits/payments	(2,363.9)		(497.2)		(128.8)		(2,989.9)
Balance as of December 31, 2024	539.1		127.8		93.5		760.4
Provisions	2,751.7		421.1		119.7		3,292.5
Credits/payments	(2,659.2)		(400.7)		(122.2)		(3,182.1)
Balance as of December 31, 2025	$	631.6	$	148.2	$	91.0	$	870.8

Legal Matters (Details) - Regeneron vs. Amgen $ in Millions	May 15, 2025 USD ($) count
Loss Contingencies [Line Items]
Number of counts ruled in favor of plaintiff \| count	9
Number of counts submitted \| count	10
Compensatory Damages
Loss Contingencies [Line Items]
Litigation settlement, gain \| $	$ 135.6
Punitive Damages
Loss Contingencies [Line Items]
Litigation settlement, gain \| $	$ 271.2

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 275
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 450
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-Name Accounting Standards Codification
-Section 50
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+ Details

Debt (Tables)

12 Months Ended

Dec. 31, 2025

Debt Disclosure [Abstract]

Summary of issued senior unsecured notes

Long-term debt, net of underwriting discounts and offering expenses (which are being amortized as additional interest expense over the period of issuance through maturity), consists of the following:


	As of December 31,
(In millions)	2025		2024
1.750% Senior Notes due September 2030	$	1,244.5	$	1,243.3
2.800% Senior Notes due September 2050	741.4		741.1
	$	1,985.9	$	1,984.4

Income Taxes - Schedule of components of income tax expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Current:
Federal	$ 1,012.3	$ 1,092.6	$ 667.9
State	19.8	(11.1)	7.7
Foreign	479.1	43.1	407.9
Total current tax expense	1,511.2	1,124.6	1,083.5
Deferred:
Federal	(845.2)	(935.5)	(834.5)
State	(15.5)	(4.9)	(6.5)
Foreign	75.3	183.1	3.2
Total deferred tax benefit	(785.4)	(757.3)	(837.8)
Effective tax rate	$ 725.8	$ 367.3	$ 245.7

Leases - Other information related to finance lease (Details)	Dec. 31, 2025	Dec. 31, 2024
Weighted-average remaining lease term (in years):
Finance leases	1 year 2 months 12 days	2 years 2 months 12 days
Operating leases	6 years 10 months 24 days	7 years 2 months 12 days
Weighted-average discount rate:
Finance leases	4.40%	5.03%
Operating leases	5.38%	5.52%

Business Overview and Summary of Significant Accounting Policies - Schedule of Estimated Useful Lives (Details)	Dec. 31, 2025
Building and improvements \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	10 years
Building and improvements \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	50 years
Laboratory equipment \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	3 years
Laboratory equipment \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	10 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	5 years

Debt - Summary of Issued Senior Unsecured Notes (Details) - Senior unsecured notes - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Long-term debt	$ 1,985.9	$ 1,984.4
1.750% Senior Notes due September 2030
Debt Instrument [Line Items]
Interest rate	1.75%
Long-term debt	$ 1,244.5	1,243.3
2.800% Senior Notes due September 2050
Debt Instrument [Line Items]
Interest rate	2.80%
Long-term debt	$ 741.4	$ 741.1

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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+ Details

Business Overview and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Business Overview and Summary of Significant Accounting Policies

Organization and Business

Regeneron Pharmaceuticals, Inc. and its subsidiaries ("Regeneron," "Company," "we," "us," and "our") is a fully integrated biotechnology company that invents, develops, manufactures, and commercializes medicines for people with serious diseases. The Company's products and product candidates in development are designed to help patients with eye diseases, allergic and inflammatory diseases, cancer, cardiovascular and metabolic diseases, neurological diseases, hematologic conditions, infectious diseases, and rare diseases. The Company's research and development efforts have led to numerous products that have received marketing approval. The Company is a party to collaboration and license agreements to develop and commercialize, as applicable, certain products and product candidates (see Note 3).

The Company's business is subject to certain risks including, but not limited to, uncertainties relating to conducting research activities, product development, obtaining regulatory approvals, competition, and obtaining and enforcing patents.

Basis of Presentation

The consolidated financial statements include the accounts of Regeneron and its wholly-owned subsidiaries. Intercompany balances and transactions are eliminated in consolidation.

Use of Estimates

The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.

Concentration of Credit Risk

Financial instruments which potentially expose the Company to concentrations of credit risk consist of cash, cash equivalents, and certain investments. In accordance with the Company's policies, the Company mandates asset diversification and monitors exposure with its counterparties.

In addition, receivables from customers (see Note 2) and collaborators (see Note 3) may subject the Company to credit risk. The Company has contractual payment terms with each of its customers and collaborators, and the Company monitors their financial performance and credit worthiness so that it can properly assess and respond to any changes in their credit profile.

Significant Accounting Policies

Cash and Cash Equivalents

The Company considers all highly liquid debt instruments with a maturity of three months or less when purchased to be cash equivalents. The carrying amount reported in the Consolidated Balance Sheet for cash and cash equivalents approximates its fair value.

Debt and Equity Securities

The Company has an investment policy that includes guidelines on acceptable investment securities, minimum credit quality, maturity parameters, and diversification. The Company invests its cash primarily in debt securities. The Company classifies its investments in debt securities as available-for-sale, with such investments carried at fair value and unrealized gains and losses included in accumulated other comprehensive income (loss). Realized gains and losses on available-for-sale debt securities are included in other income (expense), net. The Company reviews its portfolio of available-for-sale debt securities, using both quantitative and qualitative factors, to determine if declines in fair value below cost have resulted from a credit-related loss or other factors. If the decline in fair value is due to credit-related factors, a loss is recognized in net income, whereas if the decline in fair value is not due to credit-related factors, the loss is recorded in other comprehensive income (loss).

The Company also has investments in equity securities that are carried at fair value, with changes in fair value recognized within other income (expense), net. The Company has elected to measure certain equity investments it holds that do not have readily determinable fair values at cost less impairment, if any, and adjusts for observable price changes in orderly transactions for identical or similar investments of the same issuer within other income (expense), net.

Accounts Receivable

The Company's trade accounts receivable arise from product sales and represent amounts due from its customers. In addition, the Company records accounts receivable arising from its collaboration and licensing agreements. The Company provides allowances against receivables for estimated losses, if any, that may result from a counterparty's inability to pay. Amounts determined to be uncollectible are written-off against the allowance.

Inventories

Inventories are stated at the lower of cost or net realizable value. The Company determines the cost of inventory using the first-in, first-out, or FIFO, method.

The Company capitalizes inventory costs associated with the Company's products prior to regulatory approval when, based on management's judgment, future commercialization is considered probable and future economic benefit is expected to be realized; otherwise, such costs are expensed. The determination to capitalize inventory costs is based on various factors, including status and expectations of the regulatory approval process, any known safety or efficacy concerns, potential labeling restrictions, and any other impediments to obtaining regulatory approval.

The Company periodically analyzes its inventory levels to identify inventory that may expire prior to expected sale or has a cost basis in excess of its estimated realizable value. In addition, the Company's products are subject to strict quality control and monitoring which the Company performs throughout the manufacturing process. If certain batches or units of product no longer meet quality specifications or become obsolete due to expiration, the Company records a charge to write down such inventory to its estimated realizable value.

Property, Plant, and Equipment

Property, plant, and equipment are stated at cost, net of accumulated depreciation. Depreciation is calculated on a straight-line basis over the estimated useful lives of the assets. Leasehold improvements are amortized over the shorter of the estimated useful lives of the assets or the remaining lease term. Costs of construction of certain long-lived assets include capitalized interest, which is amortized over the estimated useful life of the related asset. Expenditures for maintenance and repairs which do not materially extend the useful lives of the assets are charged to expense as incurred. The cost and accumulated depreciation or amortization of assets retired or sold are removed from the respective accounts, and any gain or loss is recognized within income from operations. The estimated useful lives of property, plant, and equipment are as follows:


Building and improvements						10–50 years
Laboratory and other equipment						3–10 years
Furniture and fixtures						5 years

The Company periodically assesses the recoverability of long-lived assets, such as property, plant, and equipment, and evaluates such assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable.

Leases

The Company determines if an arrangement is a lease considering whether there is an identified asset and the contract conveys the right to control its use. Leases with an initial term of 12 months or less are not recorded on the balance sheet. The Company includes options to extend or terminate a lease when determining the lease term if it is reasonably certain that it will exercise that option. The Company accounts for lease components (e.g., rental payments) separately from non-lease components (e.g., common area maintenance costs).

Lease liabilities are recognized at the lease commencement date based on the present value of the remaining lease payments, discounted using the rate implicit in the lease. For leases where an implicit rate is not readily determinable, the Company uses its incremental borrowing rate based on information available at the lease commencement date. Lease expense for operating leases is recognized on a straight-line basis over the expected lease term.

Acquisitions

The Company makes a determination whether a transaction should be accounted for as a business combination or as an asset acquisition.

In a business combination, the acquisition method of accounting generally requires that the assets acquired and liabilities assumed be recorded as of the date of the acquisition at their respective fair values. Amounts allocated to acquired in-process research and

development are capitalized as indefinite-lived intangible assets. Any excess of the purchase price (consideration transferred) over the fair values of net assets acquired is recorded as goodwill. Contingent consideration obligations are recorded at fair value as of the acquisition date and remeasured each subsequent reporting period until the contingencies have been resolved, with any changes in fair value recorded in Other operating (income) expense, net.

If it is determined that the assets acquired do not meet the definition of a business, or if substantially all of the fair value of the assets acquired are concentrated in a single identifiable asset, then the transaction is accounted for as an asset acquisition rather than a business combination. In an asset acquisition, assets acquired are recorded at cost, goodwill is not recognized, and acquired in-process research and development with no alternative future use is charged to expense.

Intangible Assets

Intangible assets acquired in a business combination are recorded at fair value, while intangible assets acquired in connection with an asset acquisition are recorded at cost.

Payments to acquire intangible assets in an asset acquisition may include up-front payments and contingent consideration. With regard to contingent consideration in an asset acquisition, the Company recognizes regulatory milestones upon achievement, royalties in the period in which the underlying sales occur, and sales-based milestones when the milestone is deemed probable by the Company of being achieved. If contingent consideration is recognized subsequent to the acquisition date in an asset acquisition, the amount of such consideration is recorded as an addition to the cost basis of the intangible asset with a cumulative catch-up adjustment for amortization expense as if the additional amount of consideration had been accrued from the outset of the acquisition.

Indefinite-lived intangible assets are subject to impairment testing until completion or abandonment of the associated research and development efforts. Definite-lived intangible assets are amortized to Cost of goods sold over the estimated useful lives of the assets based on the pattern in which the economic benefits of the intangible assets are consumed; if that pattern cannot be reliably determined, a straight-line basis is used.

Intangible assets are reviewed for recoverability whenever events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. If an indicator of impairment exists, the Company compares the projected undiscounted cash flows to be generated by the asset to the intangible asset's carrying amount. If the projected undiscounted cash flows of the intangible asset are less than the carrying amount, an impairment loss is recognized within operating expenses and the intangible asset is written down to its fair value in the period in which the impairment occurs.

Product Revenue

Revenue from product sales is recognized at a point in time when the Company's customer is deemed to have obtained control of the product, which generally occurs upon receipt or acceptance by its customer.

The amount of revenue the Company recognizes from product sales may vary due to rebates, chargebacks, discounts, distribution-related fees, and other sales-related deductions. In order to determine the transaction price, the Company estimates, utilizing the expected value method, the amount of variable consideration to which the Company will be entitled. This estimate is based upon contracts with customers, healthcare providers, payors, and government agencies, statutorily-defined discounts applicable to government-funded programs, historical experience, estimated payor mix, and other relevant factors. The Company reviews its estimates of rebates, chargebacks, and other applicable provisions each period and records any necessary adjustments in the current period's net product sales.

•Rebates: The Company's rebates include amounts paid to managed care organizations, group purchasing organizations, state Medicaid programs, the Medicare Part D program, and other rebate programs. Outside the United States, the Company's rebates are generally contractual or legislatively mandated. The Company estimates reductions to product sales for each type of rebate and records an allowance for rebates in the same period in which the related product sales are recognized. The Company's liability for rebates consists of estimates for claims related to the current and prior periods that have not been paid and estimates for claims that will be made related to product that exists in the distribution channel at the end of the period.

•Chargebacks and Discounts: The Company's reserves related to discounted pricing to eligible physicians, Veterans' Administration ("VA"), Public Health Services, and others (collectively, "qualified healthcare providers") represent the Company's estimated obligations resulting from contractual commitments to sell products to qualified healthcare providers at prices lower than the list prices the Company charges to its customers (e.g., distributors and specialty pharmacies). The Company's customers charge the Company for the difference between what they pay for the products and the discounted selling price to the qualified healthcare providers. The Company estimates reductions to product sales for each type of chargeback and records an allowance for chargebacks in the same period that the related product sales are recognized. The Company's reserve for chargebacks consists of amounts for which it expects to issue credit based on expected sales by its customers to qualified healthcare providers and chargebacks that customers have claimed but for which the Company has not yet issued credit.

•Distribution-Related Fees: The Company has written contracts with its customers that include terms for distribution-related fees. The Company estimates and records distribution and related fees due to its customers generally based on gross sales.

•Other Sales-Related Deductions: The Company's other sales-related deductions include copay assistance programs and product returns. The Company estimates and records other sales-related deductions generally based on gross sales, written contracts, and other relevant factors. Consistent with industry practice, the Company generally offers its customers a limited right to return product purchased directly from the Company, which is principally based upon the product's expiration date. Product returned is generally not resalable given the nature of the Company's products and method of administration. The Company develops estimates for product returns based upon historical experience, shelf life of the product, and other relevant factors. The Company monitors product supply levels in the distribution channel, as well as sales by its customers, using product-specific data provided by its customers. If necessary, the Company's estimates of product returns may be adjusted in the future based on actual returns experience, known or expected changes in the marketplace, or other factors.

Collaborative Arrangements

The Company has entered into various collaborative arrangements to research, develop, manufacture, and commercialize products and/or product candidates. Although each of these arrangements is unique in nature, such arrangements involve a joint operating activity where both parties are active participants in the activities of the collaboration and exposed to significant risks and rewards dependent on the commercial success of the activities.

In arrangements where the Company does not deem its collaborator to be its customer, payments to and from its collaborator are presented in the Company's statement of operations based on the nature of Regeneron's business operations, the nature of the arrangement, including the contractual terms, and the nature of the payments. In general, the presentation of such amounts is summarized below.


Nature/Type of Payment						Statement of Operations Presentation
Regeneron's share of profits or losses in connection with commercialization of products						Collaboration revenue
Reimbursement for manufacturing of commercial supplies						Collaboration revenue
Royalties and/or sales-based milestones earned						Collaboration revenue
Reimbursement of Regeneron's research and development expenses						Reduction to Research and development expense
Regeneron's obligation for its share of collaborator's research and development expenses						Research and development expense
Reimbursement of Regeneron's commercialization-related expenses						Reduction to Selling, general, and administrative expense
Regeneron's obligation to pay collaborator for its share of gross profits when Regeneron is deemed to be the principal						Cost of goods sold

In agreements involving multiple goods or services promised to be transferred to the Company's collaborator, the Company assesses, at the inception of the contract, whether each promise represents a separate obligation (i.e., is "distinct"), or whether such promises should be combined as a single unit of account.

When the Company is entitled to reimbursement of all or a portion of the expenses (e.g., research and development expenses) that it incurs under a collaboration, it records those reimbursable amounts in the period in which such costs are incurred.

When the Company enters into an arrangement with another party to fund its research and development expenses, the Company considers whether the costs that it may be obligated to repay represent a liability within the scope of Accounting Standards

Codification ("ASC") 730-20, Research and Development. If the Company concludes that such funding does not represent a substantive and genuine transfer of risk, a liability is recorded.

If the Company's collaborator performs research and development work or commercialization-related activities and the parties share the related costs, the Company also recognizes, as expense (e.g., research and development expense or selling, general, and administrative expense, as applicable) in the period when its collaborator incurs such expenses, the portion of the collaborator's expenses that the Company is obligated to reimburse. The Company's collaborators provide the Company with estimated expenses for the most recent fiscal quarter. The estimates are revised, if necessary, in subsequent periods if actual expenses differ from those estimates.

Under certain of the Company's collaboration agreements, product sales and cost of sales may be recorded by the Company's collaborators as they are deemed to be the principal in the transaction. In arrangements where the Company:

•supplies commercial product to its collaborator, the Company may be reimbursed for its manufacturing costs as commercial product is shipped to the collaborator (however, recognition of such cost reimbursements may be deferred until the product is sold by the Company's collaborator to third-party customers);

•shares in any profits or losses arising from the commercialization of such products, the Company records its share of the variable consideration, representing net product sales less cost of goods sold and shared commercialization and other expenses, in the period in which such underlying sales occur and costs are incurred by the collaborator; and

•receives royalties and/or sales-based milestone payments from its collaborator, the Company recognizes such amounts in the period earned.

The Company's collaborators provide it with estimates of product sales and the Company's share of profits or losses, as applicable, for each quarter. The estimates are revised, if necessary, in subsequent periods if the Company's actual share of profits or losses differ from those estimates.

Research and Development Expenses

Research and development expenses include costs attributable to the conduct of research and development programs, including the cost of salaries, payroll taxes, employee benefits, materials, supplies, depreciation on and maintenance of research equipment, costs related to research collaboration and licensing agreements, clinical trial expenses, the cost of services provided by outside contractors, including services related to the Company's clinical trials, the cost of manufacturing drug for use in research and development, amounts that the Company is obligated to reimburse to collaborators for research and development expenses that they incur, and the allocable portions of facility costs. Costs associated with research and development are expensed as incurred.

For each clinical trial that the Company conducts, certain clinical trial costs are expensed immediately, while others are expensed over time based on the expected total number of patients in the trial, the rate at which patients enter and remain in the trial, and/or the period over which clinical investigators, contract research organizations ("CROs"), or other third-party service providers are expected to provide services. In the event of early termination of a clinical trial, the Company accrues and recognizes expenses in an amount based on its estimate of the remaining noncancelable obligations associated with the winding-down of the clinical trial, including any applicable penalties.

Acquired In-Process Research and Development ("IPR&D") Expenses

Acquired IPR&D expenses may include in-process research and development acquired in connection with asset acquisitions, as well as up-front, opt-in, development milestone payments, and premiums paid on equity securities related to collaboration and licensing agreements.

Stock-based Compensation

The Company recognizes stock-based compensation expense for equity grants under the Company's long-term incentive plans (including stock options, restricted stock awards, and restricted stock units (both time-based and performance-based)) to employees and non-employee members of the Company's board of directors based on the grant-date fair value of those awards. The grant-date fair value of an award is generally recognized as compensation expense over the award's requisite service period. Stock-based compensation expense also includes an estimate, which is made at the time of grant, of the number of awards that are expected to be forfeited. The forfeiture rate estimate is calculated by considering both historical forfeiture experience and an estimate of expected future forfeitures for currently outstanding unvested awards. This estimate is reviewed at least annually and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates.

The Company uses the Black-Scholes model to compute the estimated fair value of stock option awards. Additionally, the Company uses a Monte Carlo simulation to compute the estimated fair value of performance-based restricted stock units that are subject to vesting based on the Company’s attainment of pre-established criteria that include a market condition.

For performance-based restricted stock units that contain a performance condition, the Company recognizes stock-based compensation expense if and when the Company determines that it is probable the performance condition will be achieved (based on the number of shares expected to be vested and issued). The Company reassesses the probability of achievement at each reporting period and adjusts compensation cost, as necessary. If there are any changes in the Company's probability assessment, the Company recognizes a cumulative catch-up adjustment in the period of the change in estimate, with the remaining unrecognized expense recognized prospectively over the remaining requisite service period. If the Company subsequently determines that the performance criteria are not met or are not expected to be met, any amounts previously recognized as compensation expense are reversed in the period when such determination is made.

Income Taxes

The provision for income taxes includes U.S. federal, state, local, and foreign taxes. Income taxes are accounted for under the liability method. Deferred tax assets and liabilities are recognized for the expected future tax consequences of events that have been included in the financial statements or tax returns, including deferred tax assets and liabilities for expected amounts of Net CFC Tested Income (“NCTI”) (formerly known as global intangible low-taxed income ("GILTI")) inclusions. Deferred tax assets and liabilities are determined as the difference between the tax basis of assets and liabilities and their respective financial reporting amounts ("temporary differences") at enacted tax rates in effect for the years in which the differences are expected to reverse. A valuation allowance is established for deferred tax assets for which it is more likely than not that some portion or all of the deferred tax assets will not be realized.

The Company recognizes the financial statement effects of a tax position when management's assessment is that there is more than a 50% probability that the position will be sustained upon examination by a taxing authority based upon its technical merits. Uncertain tax positions are recorded based upon certain recognition and measurement criteria. The Company re-evaluates uncertain tax positions and considers 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. The Company adjusts the amount of the liability to reflect any subsequent changes in the relevant facts and circumstances surrounding the uncertain tax positions. The Company recognizes interest and penalties related to income tax matters in income tax expense.

Per Share Data

Basic net income per share is computed by dividing net income by the weighted average number of shares of Common Stock and Class A Stock outstanding. Net income per share is presented on a combined basis, inclusive of Common Stock and Class A Stock outstanding, as each class of stock has equivalent economic rights. Basic net income per share excludes restricted stock until vested. Diluted net income per share includes the potential dilutive effect of common stock equivalents as if such securities were converted or exercised during the period, when the effect is dilutive. Common stock equivalents include outstanding stock options and unvested restricted stock under the Company's long-term incentive plans, which are included under the treasury stock method when dilutive.

Recently Issued Accounting Standards

Standard/Description

Effective Date

Impact of Adoption on the Company's Financial Statements

ASU 2023-09: In December 2023, the FASB issued amended guidance related to improvements to income tax disclosures. The amendments require annually (i) enhanced disclosures in connection with an entity's effective tax rate reconciliation and (ii) income taxes paid disaggregated by jurisdiction.

January 1, 2025

Adopted prospectively; see Note 15

ASU 2024-03: In November 2024, the FASB issued new guidance which requires disclosure of disaggregated income statement expense information about specific categories (including purchases of inventory, employee compensation, depreciation, and intangible asset amortization) in the notes to financial statements.

January 1, 2027 for annual reporting periods and January 1, 2028 for interim reporting periods

Currently evaluating impact

ASU 2025-06: In September 2025, the FASB issued new guidance to modernize the accounting for software costs by updating the criteria as to when entities are required to start capitalizing internal-use software (by removing all references to software development "projects stages").

January 1, 2028

Early adopted January 1, 2026; no significant impact expected

Collaboration, License, and Other Agreements - Schedule of Collaboration Revenue Earned From Sanofi (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Revenues	$ 14,342.9	$ 14,202.0	$ 13,117.2
Sanofi Collaboration Agreement, Antibody \| Collaboration revenue \| Regeneron's share of profits
Disaggregation of Revenue [Line Items]
Revenues	5,241.6	3,923.5	3,136.5
Sanofi Collaboration Agreement, Antibody \| Collaboration revenue \| Sales-based milestones earned
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	50.0
Sanofi Collaboration Agreement, Antibody \| Collaboration revenue \| Reimbursement for manufacturing of commercial supplies
Disaggregation of Revenue [Line Items]
Revenues	642.4	607.9	613.0
Sanofi Collaboration Agreement, Antibody \| (R&D expense) \| Regeneron's obligation for its share of Sanofi R&D expenses, net of reimbursement of R&D expenses
Disaggregation of Revenue [Line Items]
Revenues	(69.5)	(46.8)	(83.7)
Sanofi Collaboration Agreement, Antibody \| Reduction of SG&A expense \| Reimbursement of commercialization-related expenses
Disaggregation of Revenue [Line Items]
Revenues	$ 729.3	$ 655.4	$ 534.4

Leases

12 Months Ended

Dec. 31, 2025

Leases [Abstract]

Leases

The Company conducts certain of its research, development, and administrative activities at leased facilities. The Company also leases vehicles and other assets.

Tarrytown, New York Corporate Headquarters

The Company leases laboratory and office facilities for its corporate headquarters in Tarrytown, New York (the "Facility") under the Third Amended and Restated Lease and Remedies Agreement (the "Lease") with BA Leasing BSC, LLC, an affiliate of Banc of America Leasing & Capital, LLC ("BAL"), as lessor, and the Third Amended and Restated Participation Agreement (the "Participation Agreement") with Bank of America, N.A., as administrative agent, and a syndicate of lenders (collectively with BAL, the "Participants"), as rent assignees. The Lease, Participation Agreement, and certain related agreements provide for $720.0 million of lease financing (previously advanced by the Participants in March 2017 in connection with the acquisition by BAL of the Facility and the Company's lease of the Facility from BAL), which matures when the term of the Lease expires in March 2027, at which time all amounts outstanding thereunder will become payable in full. The Company has the option to further extend the maturity date of the Participation Agreement and the term of the Lease for an additional five-year period, subject to the consent of the Participants and certain other conditions. The Company also has the option to (a) purchase the Facility by paying an amount equal to the outstanding principal amount of the Participants' advances under the Participation Agreement, all accrued and unpaid yield thereon, and all other outstanding amounts under the Participation Agreement, Lease, and certain related documents or (b) sell the Facility to a third party on behalf of BAL.

Pursuant to the Lease, the Company pays all maintenance, insurance, taxes, and other costs arising out of the use of the Facility. The Company is also required to make monthly payments of basic rent to satisfy the yield payable to the Participants on their outstanding advances under the Participation Agreement. Such advances accrue yield at a variable rate per annum based on the one-month forward-looking Secured Overnight Financing Rate ("SOFR") term rate, plus a spread adjustment, plus an applicable margin that varies with the Company's debt rating and total leverage ratio.

The Lease is classified as a finance lease as the Company has the option to purchase the Facility under terms that make it reasonably certain to be exercised. The agreements governing the Lease financing contain financial and operating covenants. Such financial covenants and certain of the operating covenants are substantially similar to the covenants set forth in the Credit Agreement. The Company was in compliance with all such covenants as of December 31, 2025.

Aggregate Lease Information

Amounts recognized in the Consolidated Balance Sheet related to the Company's leases are included in the table below.


		As of December 31,
(In millions)	Classification	2025		2024
Assets:
Finance lease right-of-use assets	Property, plant, and equipment, net(a)	$	576.7	$	591.2
Operating lease right-of-use assets	Other noncurrent assets(b)	245.8		217.4
		$	822.5	$	808.6

Liabilities:
Finance lease liabilities - noncurrent	Finance lease liabilities	$	720.0	$	720.0
Operating lease liabilities - current	Accrued expenses and other current liabilities	37.8		30.3
Operating lease liabilities - noncurrent	Other noncurrent liabilities	229.0		204.1
		$	986.8	$	954.4

(a) Finance lease right-of-use assets were recorded net of accumulated amortization of $162.9 million and $148.4 million as of December 31, 2025 and 2024, respectively
(b) Operating lease right-of-use assets were recorded net of accumulated amortization of $68.8 million and $78.4 million as of December 31, 2025 and 2024, respectively

Lease costs consist of the following:


	Year Ended December 31,
(In millions)	2025		2024		2023
Operating lease costs	$	35.8	$	36.5	$	19.2
Finance lease costs:
Amortization of finance lease right-of-use assets	14.5		14.5		14.5
Interest on finance lease liabilities	39.1		46.1		45.0
Total finance lease costs	53.6		60.6		59.5

Total lease costs	$	89.4	$	97.1	$	78.7

Other information related to the Company's leases includes the following:


	As of December 31,
	2025	2024
Weighted-average remaining lease term (in years):
Finance leases	1.2	2.2
Operating leases	6.9	7.2
Weighted-average discount rate:
Finance leases	4.40%	5.03%
Operating leases	5.38%	5.52%

Supplemental cash flow information related to the Company's leases includes the following:


	Year Ended December 31,
(In millions)	2025		2024		2023
Cash paid for amounts included in the measurement of operating lease liabilities (included within cash flows from operating activities)	$	39.6	$	41.4	$	22.5
Right-of-use assets obtained in exchange for operating lease liabilities	$	59.1	$	188.1	$	31.9

The following is a maturity analysis of the Company's lease liabilities as of December 31, 2025:


(In millions)	Finance Leases		Operating Leases		Total
2026	$	33.7	$	52.1	$	85.8
2027	727.6		52.3		779.9
2028	—		48.5		48.5
2029	—		40.3		40.3
2030	—		31.2		31.2
Thereafter	—		97.5		97.5
Total undiscounted lease payments	761.3		321.9		1,083.2
Imputed interest	(41.3)		(55.1)		(96.4)
Total lease liabilities	$	720.0	$	266.8	$	986.8

Leases

The Company conducts certain of its research, development, and administrative activities at leased facilities. The Company also leases vehicles and other assets.

Tarrytown, New York Corporate Headquarters

Aggregate Lease Information

Amounts recognized in the Consolidated Balance Sheet related to the Company's leases are included in the table below.


		As of December 31,
(In millions)	Classification	2025		2024
Assets:
Finance lease right-of-use assets	Property, plant, and equipment, net(a)	$	576.7	$	591.2
Operating lease right-of-use assets	Other noncurrent assets(b)	245.8		217.4
		$	822.5	$	808.6

Liabilities:
Finance lease liabilities - noncurrent	Finance lease liabilities	$	720.0	$	720.0
Operating lease liabilities - current	Accrued expenses and other current liabilities	37.8		30.3
Operating lease liabilities - noncurrent	Other noncurrent liabilities	229.0		204.1
		$	986.8	$	954.4

(a) Finance lease right-of-use assets were recorded net of accumulated amortization of $162.9 million and $148.4 million as of December 31, 2025 and 2024, respectively
(b) Operating lease right-of-use assets were recorded net of accumulated amortization of $68.8 million and $78.4 million as of December 31, 2025 and 2024, respectively

Lease costs consist of the following:


	Year Ended December 31,
(In millions)	2025		2024		2023
Operating lease costs	$	35.8	$	36.5	$	19.2
Finance lease costs:
Amortization of finance lease right-of-use assets	14.5		14.5		14.5
Interest on finance lease liabilities	39.1		46.1		45.0
Total finance lease costs	53.6		60.6		59.5

Total lease costs	$	89.4	$	97.1	$	78.7

Other information related to the Company's leases includes the following:


	As of December 31,
	2025	2024
Weighted-average remaining lease term (in years):
Finance leases	1.2	2.2
Operating leases	6.9	7.2
Weighted-average discount rate:
Finance leases	4.40%	5.03%
Operating leases	5.38%	5.52%

Supplemental cash flow information related to the Company's leases includes the following:


	Year Ended December 31,
(In millions)	2025		2024		2023
Cash paid for amounts included in the measurement of operating lease liabilities (included within cash flows from operating activities)	$	39.6	$	41.4	$	22.5
Right-of-use assets obtained in exchange for operating lease liabilities	$	59.1	$	188.1	$	31.9

The following is a maturity analysis of the Company's lease liabilities as of December 31, 2025:


(In millions)	Finance Leases		Operating Leases		Total
2026	$	33.7	$	52.1	$	85.8
2027	727.6		52.3		779.9
2028	—		48.5		48.5
2029	—		40.3		40.3
2030	—		31.2		31.2
Thereafter	—		97.5		97.5
Total undiscounted lease payments	761.3		321.9		1,083.2
Imputed interest	(41.3)		(55.1)		(96.4)
Total lease liabilities	$	720.0	$	266.8	$	986.8

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2025	Dec. 31, 2024
LIABILITIES AND STOCKHOLDERS' EQUITY
Preferred Stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred Stock, shares authorized (in shares)	30,000,000	30,000,000.0
Preferred Stock, shares issued (in shares)	0	0
Preferred Stock, shares outstanding (in shares)	0	0
Treasury stock (in shares)	33,700,000	28,200,000
Class A Stock
LIABILITIES AND STOCKHOLDERS' EQUITY
Common Stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common Stock, shares authorized (in shares)	40,000,000	40,000,000.0
Common Stock, shares issued (in shares)	1,800,000	1,800,000
Common Stock, shares outstanding (in shares)	1,800,000	1,800,000
Common Stock
LIABILITIES AND STOCKHOLDERS' EQUITY
Common Stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common Stock, shares authorized (in shares)	320,000,000	320,000,000.0
Common Stock, shares issued (in shares)	137,600,000	136,000,000.0

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2025

Fair Value Disclosures [Abstract]

Schedule of assets measured at fair value on a recurring basis

The table below summarizes the Company's assets and liabilities which are measured at fair value on a recurring basis. The following fair value hierarchy is used to classify assets and liabilities, based on inputs to valuation techniques utilized to measure fair value:

•Level 1 - Quoted prices in active markets for identical assets or liabilities

•Level 2 - Significant other observable inputs, such as quoted market prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, or model-based valuations in which significant inputs used are observable

•Level 3 - Significant other unobservable inputs


(In millions)			Fair Value Measurements at Reporting Date
As of December 31, 2025	Fair Value		Level 1		Level 2		Level 3
Assets:
Cash equivalents	$	2,121.6	$	1,127.7	$	993.9	$	—
Available-for-sale debt securities:
Corporate bonds	10,219.5		—		10,219.5		—
U.S. government and government agency obligations	4,367.3		—		4,367.3		—
Commercial paper	541.1		—		541.1		—
Certificates of deposit	265.9		—		265.9		—
Asset-backed securities	242.8		—		242.8		—
Sovereign bonds	76.8		—		76.8		—
Equity securities(a)	34.3		34.3		—		—
Total assets	$	17,869.3	$	1,162.0	$	16,707.3	$	—

Liabilities:
Contingent consideration	$	10.3	$	—	$	—	$	10.3

As of December 31, 2024
Assets:
Cash equivalents	$	1,452.2	$	1,264.2	$	188.0	$	—
Available-for-sale debt securities:
Corporate bonds	8,220.6		—		8,220.6		—
U.S. government and government agency obligations	4,817.0		—		4,817.0		—
Commercial paper	548.7		—		548.7		—
Certificates of deposit	381.1		—		381.1		—
Asset-backed securities	279.3		—		279.3		—
Sovereign bonds	82.4		—		82.4		—
Equity securities(a)	1,095.3		1,095.3		—		—
Total assets	$	16,876.6	$	2,359.5	$	14,517.1	$	—

Liabilities:
Contingent consideration	$	52.3	$	—	$	—	$	52.3

(a) Includes equity securities of $33.3 million and $43.2 million as of December 31, 2025 and 2024, respectively, that are subject to transfer restrictions expiring in April 2026

Schedule of unrealized gains on investments

Amounts recognized in Other income (expense), net, related to the Company's investments in public equity securities consist of the following:


	Year Ended December 31,
(In millions)	2025		2024		2023
Net gains (losses) recognized during the period	$	955.6	$	117.7	$	(235.6)
Less: Net gains recognized on investments sold during the period	966.2		—		6.0
Net unrealized gains (losses) recognized on investments still held as of period end date	$	(10.6)	$	117.7	$	(241.6)

Property, Plant, and Equipment

12 Months Ended

Dec. 31, 2025

Property, Plant and Equipment [Abstract]

Property, Plant, and Equipment

Property, plant, and equipment, net consists of the following:


	As of December 31,
(In millions)	2025		2024
Building and improvements	$	3,105.9	$	2,573.2
Leasehold improvements	174.4		154.5
Laboratory equipment	1,543.7		1,494.5
Computer equipment and software	522.0		450.8
Furniture, office equipment, and other	219.7		203.8
Land	278.8		288.2
Construction in progress	1,890.2		1,721.6
	7,734.7		6,886.6
Accumulated depreciation and amortization	(2,614.3)		(2,286.9)
	$	5,120.4	$	4,599.7

Property, plant, and equipment in the table above includes leased property under the Company's finance lease at its Tarrytown, New York corporate headquarters. See Note 11.

Depreciation and amortization expense on property, plant, and equipment was $364.8 million, $354.1 million, and $328.8 million for the years ended December 31, 2025, 2024, and 2023, respectively.

As of December 31, 2025 and 2024, $4.332 billion and $3.884 billion, respectively, of the Company's net property, plant, and equipment was located in the United States and $788.0 million and $715.9 million, respectively, was located outside the United States (primarily in Ireland).

Debt

12 Months Ended

Dec. 31, 2025

Debt Disclosure [Abstract]

Debt

a. Senior Notes

Long-term debt, net of underwriting discounts and offering expenses (which are being amortized as additional interest expense over the period of issuance through maturity), consists of the following:


	As of December 31,
(In millions)	2025		2024
1.750% Senior Notes due September 2030	$	1,244.5	$	1,243.3
2.800% Senior Notes due September 2050	741.4		741.1
	$	1,985.9	$	1,984.4

Interest on each series of senior notes is payable semi-annually until the applicable maturity dates. Interest expense related to the debt was $44.4 million in each of the years ended December 31, 2025, 2024, and 2023.

b. Credit Facility

The Company is party to an agreement with a syndicate of lenders (the "Credit Agreement") which provides for a $750.0 million senior unsecured five-year revolving credit facility (the "Credit Facility"). The Credit Agreement includes an option for the Company to elect to increase the commitments under the Credit Facility and/or to enter into one or more tranches of term loans in the aggregate principal amount of up to $500.0 million, subject to the consent of the lenders providing the additional commitments or term loans, as applicable, and certain other conditions. The Credit Agreement also provides a $50.0 million sublimit for letters of credit.

Proceeds of the loans under the Credit Facility may be used to finance working capital needs, and for general corporate or other lawful purposes, of Regeneron and its subsidiaries. Regeneron Pharmaceuticals, Inc. has guaranteed all obligations under the Credit Facility. The Credit Agreement includes an option for the Company to elect to extend the maturity date of the Credit Facility beyond December 2027, subject to the consent of the extending lenders and certain other conditions.

The Company had no borrowings outstanding under the Credit Facility as of December 31, 2025.

The Credit Agreement contains operating covenants and a maximum total leverage ratio financial covenant. The Company was in compliance with all covenants of the Credit Agreement as of December 31, 2025.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-8A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(c))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481544/470-10-50-6

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481544/470-10-50-6

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477092/405-40-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477092/405-40-50-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477092/405-40-50-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477092/405-40-50-1

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B

Reference 12: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 470
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/470/tableOfContent

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 835
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482925/835-30-45-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
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-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1C

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1C

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1C

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Name Accounting Standards Codification
-Section 50
-Paragraph 1E
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1E

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Name Accounting Standards Codification
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1I

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1I

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1I

+ Details

Business Overview and Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Basis of Presentation

The consolidated financial statements include the accounts of Regeneron and its wholly-owned subsidiaries. Intercompany balances and transactions are eliminated in consolidation.

Use of Estimates

Concentration of Credit Risk

In addition, receivables from customers (see Note 2) and collaborators (see Note 3) may subject the Company to credit risk.

Cash and Cash Equivalents

Debt and Equity Securities

Accounts Receivable

Inventories

Inventories are stated at the lower of cost or net realizable value. The Company determines the cost of inventory using the first-in, first-out, or FIFO, method.

Property, Plant and Equipment

Property, Plant, and Equipment


Building and improvements						10–50 years
Laboratory and other equipment						3–10 years
Furniture and fixtures						5 years

Leases

The Company conducts certain of its research, development, and administrative activities at leased facilities. The Company also leases vehicles and other assets.

Tarrytown, New York Corporate Headquarters

Acquisitions

The Company makes a determination whether a transaction should be accounted for as a business combination or as an asset acquisition.

Intangible Assets

Intangible assets acquired in a business combination are recorded at fair value, while intangible assets acquired in connection with an asset acquisition are recorded at cost.

Product Revenue

Collaborative Arrangements


Nature/Type of Payment						Statement of Operations Presentation
Regeneron's share of profits or losses in connection with commercialization of products						Collaboration revenue
Reimbursement for manufacturing of commercial supplies						Collaboration revenue
Royalties and/or sales-based milestones earned						Collaboration revenue
Reimbursement of Regeneron's research and development expenses						Reduction to Research and development expense
Regeneron's obligation for its share of collaborator's research and development expenses						Research and development expense
Reimbursement of Regeneron's commercialization-related expenses						Reduction to Selling, general, and administrative expense
Regeneron's obligation to pay collaborator for its share of gross profits when Regeneron is deemed to be the principal						Cost of goods sold

Codification ("ASC") 730-20, Research and Development. If the Company concludes that such funding does not represent a substantive and genuine transfer of risk, a liability is recorded.

•receives royalties and/or sales-based milestone payments from its collaborator, the Company recognizes such amounts in the period earned.

Research and Development Expenses

Acquired In-Process Research and Development ("IPR&D") Expenses

Stock-based Compensation

Income Taxes

Per Share Data

Recently Issued Accounting Standards

Standard/Description

Effective Date

Impact of Adoption on the Company's Financial Statements

January 1, 2025

Adopted prospectively; see Note 15

January 1, 2027 for annual reporting periods and January 1, 2028 for interim reporting periods

Currently evaluating impact

January 1, 2028

Early adopted January 1, 2026; no significant impact expected

Legal Matters

Costs associated with the Company's involvement in legal proceedings are expensed as incurred.

Legal Matters

The Company recognizes gain contingencies associated with such proceedings when the award or recovery is realized or realizable and loss contingencies when it is probable that a liability will be incurred and the amount of loss can be reasonably estimated.

Leases - Analysis of lease liability maturities (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Finance Leases
2026	$ 33.7
2027	727.6
2028	0.0
2029	0.0
2030	0.0
Thereafter	0.0
Total undiscounted lease payments	761.3
Imputed interest	(41.3)
Total lease liabilities	720.0
Operating Leases
2026	52.1
2027	52.3
2028	48.5
2029	40.3
2030	31.2
Thereafter	97.5
Total undiscounted lease payments	321.9
Imputed interest	(55.1)
Total lease liabilities	266.8
Total
2026	85.8
2027	779.9
2028	48.5
2029	40.3
2030	31.2
Thereafter	97.5
Total undiscounted lease payments	1,083.2
Imputed interest	(96.4)
Total lease liability	$ 986.8	$ 954.4

Statement of Cash Flows

12 Months Ended

Dec. 31, 2025

Cash and Cash Equivalents [Abstract]

Statement of Cash Flows

The following provides a reconciliation of cash, cash equivalents, and restricted cash reported within the Consolidated Balance Sheets to the total of the same such amounts shown in the Consolidated Statements of Cash Flows:


	December 31,
(In millions)	2025		2024		2023
Cash and cash equivalents	$	3,118.1	$	2,488.2	$	2,730.0
Restricted cash included in Other current assets	5.6		0.8		—
Restricted cash included in Other noncurrent assets	—		—		7.8
Total cash, cash equivalents, and restricted cash shown in the Consolidated Statements of Cash Flows	$	3,123.7	$	2,489.0	$	2,737.8

Restricted cash consists of amounts held pursuant to contractual arrangements and for dividends payable on certain equity awards.

Supplemental disclosure of non-cash investing and financing activities


	As of December 31,
(In millions)	2025		2024		2023
Accrued capital expenditures	$	178.8	$	151.6	$	75.4
Accrued contingent consideration in connection with acquisitions	$	58.9	$	62.7	$	71.6

Long-Term Incentive Plans - Summary of activity related to performance-based awards (Details) - Performance-based stock options shares in Millions	12 Months Ended
	Dec. 31, 2025 $ / shares shares
Number of Shares/Units (In millions)
Beginning balance (in shares) \| shares	1.4
Vested (in shares) \| shares	(1.2)
Ending balance (in shares) \| shares	0.2
Weighted-Average Grant Date Fair Value
Beginning balance (in dollars of shares) \| $ / shares	$ 247.91
Vested (in dollars of shares) \| $ / shares	209.59
Ending balance (in dollars of shares) \| $ / shares	$ 485.61

Product Sales - Schedule of Sales Related Deductions Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	$ 760.4	$ 697.3	$ 546.8
Provisions	3,292.5	3,053.0	2,669.0
Credits/payments	(3,182.1)	(2,989.9)	(2,518.5)
Ending Balance	870.8	760.4	697.3
Rebates, Chargebacks, and Discounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	539.1	455.7	353.9
Provisions	2,751.7	2,447.3	2,074.5
Credits/payments	(2,659.2)	(2,363.9)	(1,972.7)
Ending Balance	631.6	539.1	455.7
Distribution- Related Fees
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	127.8	162.3	111.4
Provisions	421.1	462.7	439.2
Credits/payments	(400.7)	(497.2)	(388.3)
Ending Balance	148.2	127.8	162.3
Other Sales- Related Deductions
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	93.5	79.3	81.5
Provisions	119.7	143.0	155.3
Credits/payments	(122.2)	(128.8)	(157.5)
Ending Balance	$ 91.0	$ 93.5	$ 79.3

Long-Term Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2025

Share-Based Payment Arrangement [Abstract]

Schedule of transactions involving stock option awards

The table below summarizes the activity related to stock option awards under the Company's Incentive Plans during 2025.


		Number of Shares (In millions)	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term	Intrinsic Value (In millions)
Outstanding as of December 31, 2024		12.7	$	588.47
2025:	Granted	0.7	$	691.40
	Forfeited	(0.4)	$	752.01
	Exercised	(1.2)	$	519.17
Outstanding as of December 31, 2025		11.8	$	596.65	5.7 years	$	2,185.9

Vested and expected to vest as of December 31, 2025		11.5	$	592.93	5.7 years	$	2,178.9

Exercisable as of December 31, 2025		8.7	$	536.47	4.7 years	$	2,100.0

Schedule of weighted-average exercise prices and weighted-average grant-date fair values of options issued

The table below summarizes the weighted-average exercise prices and weighted-average grant-date fair values of options granted during the years ended December 31, 2025, 2024, and 2023.


	Number of Options Granted (In millions)	Weighted-Average Exercise Price		Weighted-Average Fair Value
2025:
Exercise price equal to Market Price	0.7	$	691.40	$	206.58
2024:
Exercise price equal to Market Price	1.9	$	786.79	$	235.32
2023:
Exercise price equal to Market Price	1.6	$	835.91	$	264.37

Schedule of weighted-average values of assumptions used in computing fair value of option grants

The following table summarizes the weighted average values of the assumptions used in computing the fair value of option grants during 2025, 2024, and 2023.


	2025		2024		2023
Expected volatility	26	%	25	%	26	%
Expected lives from grant date	5.3 years		5.0 years		5.1 years
Expected dividend yield	0.49	%	0	%	0	%
Risk-free interest rate	3.79	%	4.11	%	4.29	%

Schedule of activity related to restricted stock awards

A summary of the Company's activity related to restricted stock awards and time-based restricted stock units (excluding performance-based restricted stock units, which are detailed further below) (collectively, "restricted stock") during 2025 is summarized below.


		Number of Shares/Units (In millions)	Weighted-Average Grant Date Fair Value
Unvested as of December 31, 2024		2.5	$	760.35
2025:	Granted	1.4	$	718.94
	Vested	(0.7)	$	734.49
	Forfeited	(0.1)	$	753.77
Unvested as of December 31, 2025		3.1	$	748.08

Schedule of activity related to performance-based restricted stock units

The table below summarizes activity related to PSUs during 2025. The number of unvested PSUs represents the maximum number of units that are eligible to be earned.


		Number of Shares/Units (In millions)	Weighted-Average Grant Date Fair Value
Unvested as of December 31, 2024		1.4	$	247.91
2025:	Vested	(1.2)	$	209.59
Unvested as of December 31, 2025		0.2	$	485.61

Property, Plant, and Equipment (Tables)

12 Months Ended

Dec. 31, 2025

Property, Plant and Equipment [Abstract]

Schedule of property, plant and equipment

The estimated useful lives of property, plant, and equipment are as follows:


Building and improvements						10–50 years
Laboratory and other equipment						3–10 years
Furniture and fixtures						5 years

Property, plant, and equipment, net consists of the following:


	As of December 31,
(In millions)	2025		2024
Building and improvements	$	3,105.9	$	2,573.2
Leasehold improvements	174.4		154.5
Laboratory equipment	1,543.7		1,494.5
Computer equipment and software	522.0		450.8
Furniture, office equipment, and other	219.7		203.8
Land	278.8		288.2
Construction in progress	1,890.2		1,721.6
	7,734.7		6,886.6
Accumulated depreciation and amortization	(2,614.3)		(2,286.9)
	$	5,120.4	$	4,599.7

Income Taxes - Schedule of effective income tax rate (Details)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
U.S. federal statutory tax rate	21.00%	21.00%	21.00%
Stock-based compensation	0.30%	(4.90%)	(4.60%)
Taxation of non-U.S. operations		(4.00%)	(6.60%)
Tax credits		(3.50%)	(3.20%)
Foreign-derived deduction eligible income	(0.40%)	(0.80%)	(0.30%)
Other permanent differences	0.50%	(0.10%)	(0.40%)
Effective tax rate	13.90%	7.70%	5.90%

Product Sales - Schedule of Concentration of Risk, by Risk Factor (Details) - Gross Product Revenue - Customer concentration risk	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Customer A
Concentration Risk [Line Items]
Concentration risk, percentage	50.00%	50.00%	51.00%
Customer B
Concentration Risk [Line Items]
Concentration risk, percentage	27.00%	24.00%	25.00%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 275
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-18

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 275
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-18

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 275
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 20
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-20

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 275
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-18

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 275
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-18

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 275
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-18

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 275
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 18
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482836/275-10-55-18

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 275
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 20
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-20

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 954
-SubTopic 310
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478785/954-310-50-2

+ Details

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References + Details

Segment Information

12 Months Ended

Dec. 31, 2025

Segment Reporting [Abstract]

Segment Information

The Company operates in one business segment, which includes all activities related to the discovery, development, and commercialization of medicines for serious diseases. The determination of a single business segment is consistent with the consolidated financial information regularly provided to the Company's chief operating decision maker ("CODM"). The Company's CODM is its Chief Executive Officer, who reviews and evaluates consolidated net income for purposes of assessing performance, making operating decisions, allocating resources, and planning and forecasting for future periods.

In addition to the significant expense categories included within consolidated net income presented on the Company's Consolidated Statements of Operations, see below for disaggregated amounts that comprise research and development expenses:


	Year Ended December 31,
(In millions)	2025		2024		2023
Direct research and development expenses(a)	$	1,758.1	$	1,588.8	$	1,295.6

Indirect research and development expenses:
Payroll and benefits	1,800.8		1,681.7		1,537.0
Lab supplies and other research and development costs	258.2		241.5		210.6
Occupancy and other operating costs	635.4		614.9		518.2
Total indirect research and development expenses	2,694.4		2,538.1		2,265.8

Clinical manufacturing costs	1,391.2		1,195.9		1,053.9

Priority review voucher	155.0		—		—

Reimbursement of research and development expenses by collaborators	(148.5)		(190.8)		(176.3)

Total research and development expenses	$	5,850.2	$	5,132.0	$	4,439.0

(a) Direct research and development expenses are comprised primarily of costs paid to third parties for clinical and product development activities, and the portion of research and development expenses incurred by our collaborators that we are obligated to reimburse

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
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+ Details

Stockholders' Equity - Narrative (Details)	1 Months Ended	3 Months Ended				12 Months Ended
Stockholders' Equity - Narrative (Details)	Jan. 31, 2026 $ / shares	Dec. 31, 2025 USD ($) $ / shares shares	Sep. 30, 2025 $ / shares	Jun. 30, 2025 $ / shares	Mar. 31, 2025 $ / shares	Dec. 31, 2025 USD ($) vote $ / shares shares	Feb. 28, 2025 USD ($)	Dec. 31, 2024 $ / shares shares
Class of Stock [Line Items]
Preferred Stock, shares authorized (in shares) \| shares		30,000,000				30,000,000		30,000,000.0
Remaining authorized repurchase amount \| $		$ 1,486,000,000				$ 1,486,000,000
Common stock, dividend, declared (in dollars per share)		$ 0.88	$ 0.88	$ 0.88	$ 0.88
Forecast
Class of Stock [Line Items]
Common stock, dividend, declared (in dollars per share)	$ 0.94
Share Repurchase Program, February 2025
Class of Stock [Line Items]
Stock repurchase program, authorized amount \| $							$ 3,000,000,000
Class A Stock
Class of Stock [Line Items]
Common Stock, shares authorized (in shares) \| shares		40,000,000				40,000,000		40,000,000.0
Common Stock, par value (in dollars per share)		$ 0.001				$ 0.001		$ 0.001
Number of votes per share \| vote						10
Common Stock
Class of Stock [Line Items]
Common Stock, shares authorized (in shares) \| shares		320,000,000				320,000,000		320,000,000.0
Common Stock, par value (in dollars per share)		$ 0.001				$ 0.001		$ 0.001
Number of votes per share \| vote						1

Product Sales - Schedule of Net Product Sales (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Revenues	$ 14,342.9	$ 14,202.0	$ 13,117.2
Net product sales
Disaggregation of Revenue [Line Items]
Revenues	6,309.1	7,629.2	7,078.0
Libtayo
Disaggregation of Revenue [Line Items]
Revenues	1,452.2	1,216.8	863.1
Other products
Disaggregation of Revenue [Line Items]
Revenues	10.1	0.0	0.0
U.S. \| ELYEA HD And EYLEA
Disaggregation of Revenue [Line Items]
Revenues	4,384.7	5,968.2	5,885.4
U.S. \| ELYEA HD
Disaggregation of Revenue [Line Items]
Revenues	1,636.9	1,201.1	165.8
U.S. \| EYLEA
Disaggregation of Revenue [Line Items]
Revenues	2,747.8	4,767.1	5,719.6
U.S. \| Libtayo
Disaggregation of Revenue [Line Items]
Revenues	944.7	787.3	538.8
U.S. \| Praluent
Disaggregation of Revenue [Line Items]
Revenues	262.5	241.7	182.4
U.S. \| Evkeeza
Disaggregation of Revenue [Line Items]
Revenues	162.2	125.7	77.3
U.S. \| Inmazeb
Disaggregation of Revenue [Line Items]
Revenues	37.4	76.8	69.8
Rest of world \| Libtayo
Disaggregation of Revenue [Line Items]
Revenues	$ 507.5	$ 429.5	$ 324.3

Leases - Supplemental cash flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Leases [Abstract]
Cash paid for amounts included in the measurement of operating lease liabilities (included within cash flows from operating activities)	$ 39.6	$ 41.4	$ 22.5
Right-of-use assets obtained in exchange for operating lease liabilities	$ 59.1	$ 188.1	$ 31.9

Net Income Per Share - Schedule of Antidilutive Securities Excluded From Computation (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number of shares (in shares)	6.2	1.6	1.8
Restricted stock awards and restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number of shares (in shares)	0.2	0.0	0.0

Cybersecurity Risk Management and Strategy Disclosure	12 Months Ended
Cybersecurity Risk Management and Strategy Disclosure	Dec. 31, 2025
Cybersecurity Risk Management, Strategy, and Governance [Line Items]
Cybersecurity Risk Management Processes for Assessing, Identifying, and Managing Threats [Text Block]	We regularly assess risks from cybersecurity threats; monitor our information systems for potential vulnerabilities; and test those systems pursuant to our cybersecurity policies, processes, and practices, which are integrated into our overall risk management program. To protect our information systems from cybersecurity threats, we use various security tools that are designed to help identify, escalate, investigate, resolve, and recover from security incidents in a timely manner. Our Technology Risk Management Committee, which is comprised of representatives from our business operations and support functions (e.g., legal, finance, internal audit, commercial, privacy), assesses cybersecurity risks based on probability and potential impact to key business systems and processes. Cybersecurity risks that are considered high are incorporated into our overall risk management program. A mitigation plan is developed for each identified high risk, with progress on risk mitigation reported to the Technology Risk Management Committee and tracked as part of our overall risk management program, which is overseen by the Audit Committee of our board of directors. We collaborate with third parties to assess the effectiveness of our cybersecurity prevention and response systems and processes. These include cybersecurity assessors, consultants, and other external cybersecurity experts to assist in the identification, verification, and validation of cybersecurity risks, as well as to support associated mitigation plans when necessary. We have also developed a process to conduct due diligence on third parties with which we work to oversee and identify material risks from cybersecurity threats associated with our use of those third parties' services, including those that perform cybersecurity services. To date, the Company is not aware of risks from cybersecurity threats, including those resulting from any previous cybersecurity incidents, that have materially affected or are reasonably likely to materially affect our Company, including our business strategy, results of operations, or financial condition. Refer to the risk factor captioned "Significant disruptions of information technology systems or breaches of data security could adversely affect our business" in Part I, Item 1A. "Risk Factors" for additional information regarding cybersecurity risks and potential related impacts on our Company.
Cybersecurity Risk Management Processes Integrated [Flag]	true
Cybersecurity Risk Management Processes Integrated [Text Block]	We regularly assess risks from cybersecurity threats; monitor our information systems for potential vulnerabilities; and test those systems pursuant to our cybersecurity policies, processes, and practices, which are integrated into our overall risk management program. To protect our information systems from cybersecurity threats, we use various security tools that are designed to help identify, escalate, investigate, resolve, and recover from security incidents in a timely manner. Our Technology Risk Management Committee, which is comprised of representatives from our business operations and support functions (e.g., legal, finance, internal audit, commercial, privacy), assesses cybersecurity risks based on probability and potential impact to key business systems and processes. Cybersecurity risks that are considered high are incorporated into our overall risk management program. A mitigation plan is developed for each identified high risk, with progress on risk mitigation reported to the Technology Risk Management Committee and tracked as part of our overall risk management program, which is overseen by the Audit Committee of our board of directors.
Cybersecurity Risk Management Third Party Engaged [Flag]	true
Cybersecurity Risk Third Party Oversight and Identification Processes [Flag]	true
Cybersecurity Risk Materially Affected or Reasonably Likely to Materially Affect Registrant [Flag]	false
Cybersecurity Risk Board of Directors Oversight [Text Block]	Our board of directors oversees our risk management process, including as it pertains to cybersecurity risks, directly and through its committees. The Audit Committee of the board oversees our risk management program, which focuses on the most significant risks we face in the short-, intermediate-, and long-term timeframe. Audit Committee meetings include discussions of specific risk areas throughout the year, including, among others, those relating to cybersecurity threats, and reports from the Chief Audit Executive on our enterprise risk profile on an annual basis. The Audit Committee reviews our cybersecurity risk profile with management on a periodic basis using key performance and/or risk indicators. These key performance indicators are metrics and measurements designed to assess the effectiveness of our cybersecurity program in the prevention, detection, mitigation, and remediation of cybersecurity incidents.
Cybersecurity Risk Board Committee or Subcommittee Responsible for Oversight [Text Block]	Audit Committee
Cybersecurity Risk Process for Informing Board Committee or Subcommittee Responsible for Oversight [Text Block]	The CISO provides periodic updates on our cybersecurity risk profile to management's Technology Risk Management Committee and the Audit Committee of our board of directors.
Cybersecurity Risk Role of Management [Text Block]	We take a risk-based approach to cybersecurity and have implemented cybersecurity policies throughout our operations that are designed to address cybersecurity threats and incidents. The Company's Chief Information Security Officer ("CISO"), in coordination with the Chief Digital & Technology Officer and the Technology Risk Management Committee, is responsible for the establishment and maintenance of our cybersecurity program, as well as the assessment and management of cybersecurity risks. The current CISO has over 35 years of experience in technology and information security, including operating in the role of the CISO for several large companies in the pharmaceutical and healthcare industries, and possesses the requisite education, skills, experience, and industry certifications expected of an individual assigned to these duties. The CISO provides periodic updates on our cybersecurity risk profile to management's Technology Risk Management Committee and the Audit Committee of our board of directors.
Cybersecurity Risk Management Positions or Committees Responsible [Flag]	true
Cybersecurity Risk Management Positions or Committees Responsible [Text Block]	The Company's Chief Information Security Officer ("CISO"), in coordination with the Chief Digital & Technology Officer and the Technology Risk Management Committee, is responsible for the establishment and maintenance of our cybersecurity program, as well as the assessment and management of cybersecurity risks. The current CISO has over 35 years of experience in technology and information security, including operating in the role of the CISO for several large companies in the pharmaceutical and healthcare industries, and possesses the requisite education, skills, experience, and industry certifications expected of an individual assigned to these duties. The CISO provides periodic updates on our cybersecurity risk profile to management's Technology Risk Management Committee and the Audit Committee of our board of directors.
Cybersecurity Risk Management Expertise of Management Responsible [Text Block]	The current CISO has over 35 years of experience in technology and information security, including operating in the role of the CISO for several large companies in the pharmaceutical and healthcare industries, and possesses the requisite education, skills, experience, and industry certifications expected of an individual assigned to these duties.
Cybersecurity Risk Process for Informing Management or Committees Responsible [Text Block]	The CISO provides periodic updates on our cybersecurity risk profile to management's Technology Risk Management Committee and the Audit Committee of our board of directors.
Cybersecurity Risk Management Positions or Committees Responsible Report to Board [Flag]	true

Fair Value Measurements - Schedule of Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Assets:
Cash equivalents	$ 2,121.6	$ 1,452.2
Available-for-sale debt securities	15,713.4	14,329.1
Equity securities	34.3	1,095.3
Total assets	17,869.3	16,876.6
Liabilities:
Contingent consideration	10.3	52.3
Restricted
Assets:
Equity securities	33.3	43.2
Corporate bonds
Assets:
Available-for-sale debt securities	10,219.5	8,220.6
U.S. government and government agency obligations
Assets:
Available-for-sale debt securities	4,367.3	4,817.0
Commercial paper
Assets:
Available-for-sale debt securities	541.1	548.7
Certificates of deposit
Assets:
Available-for-sale debt securities	265.9	381.1
Asset-backed securities
Assets:
Available-for-sale debt securities	242.8	279.3
Sovereign bonds
Assets:
Available-for-sale debt securities	76.8	82.4
Level 1
Assets:
Cash equivalents	1,127.7	1,264.2
Equity securities	34.3	1,095.3
Total assets	1,162.0	2,359.5
Liabilities:
Contingent consideration	0.0	0.0
Level 1 \| Corporate bonds
Assets:
Available-for-sale debt securities	0.0	0.0
Level 1 \| U.S. government and government agency obligations
Assets:
Available-for-sale debt securities	0.0	0.0
Level 1 \| Commercial paper
Assets:
Available-for-sale debt securities	0.0	0.0
Level 1 \| Certificates of deposit
Assets:
Available-for-sale debt securities	0.0	0.0
Level 1 \| Asset-backed securities
Assets:
Available-for-sale debt securities	0.0	0.0
Level 1 \| Sovereign bonds
Assets:
Available-for-sale debt securities	0.0	0.0
Level 2
Assets:
Cash equivalents	993.9	188.0
Equity securities	0.0	0.0
Total assets	16,707.3	14,517.1
Liabilities:
Contingent consideration	0.0	0.0
Level 2 \| Corporate bonds
Assets:
Available-for-sale debt securities	10,219.5	8,220.6
Level 2 \| U.S. government and government agency obligations
Assets:
Available-for-sale debt securities	4,367.3	4,817.0
Level 2 \| Commercial paper
Assets:
Available-for-sale debt securities	541.1	548.7
Level 2 \| Certificates of deposit
Assets:
Available-for-sale debt securities	265.9	381.1
Level 2 \| Asset-backed securities
Assets:
Available-for-sale debt securities	242.8	279.3
Level 2 \| Sovereign bonds
Assets:
Available-for-sale debt securities	76.8	82.4
Level 3
Assets:
Cash equivalents	0.0	0.0
Equity securities	0.0	0.0
Total assets	0.0	0.0
Liabilities:
Contingent consideration	10.3	52.3
Level 3 \| Corporate bonds
Assets:
Available-for-sale debt securities	0.0	0.0
Level 3 \| U.S. government and government agency obligations
Assets:
Available-for-sale debt securities	0.0	0.0
Level 3 \| Commercial paper
Assets:
Available-for-sale debt securities	0.0	0.0
Level 3 \| Certificates of deposit
Assets:
Available-for-sale debt securities	0.0	0.0
Level 3 \| Asset-backed securities
Assets:
Available-for-sale debt securities	0.0	0.0
Level 3 \| Sovereign bonds
Assets:
Available-for-sale debt securities	$ 0.0	$ 0.0

Long-Term Incentive Plans - Summary of weighted-average values of assumptions used in computing fair value of option grants (Details) - Stock options	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	26.00%	25.00%	26.00%
Expected lives from grant date	5 years 3 months 18 days	5 years	5 years 1 month 6 days
Expected dividend yield	0.49%	0.00%	0.00%
Risk-free interest rate	3.79%	4.11%	4.29%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Long-Term Incentive Plans - Summary of transactions involving stock option awards (Details) - Stock options - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Number of Shares (In millions)
Outstanding at beginning of period (in shares)	12.7
Granted (in shares)	0.7	1.9	1.6
Forfeited (in shares)	(0.4)
Exercised (in shares)	(1.2)
Outstanding at end of period (in shares)	11.8	12.7
Vested and expected to vest (in shares)	11.5
Exercisable (in shares)	8.7
Weighted-Average Exercise Price
Outstanding at beginning of period (in dollars per share)	$ 588.47
Granted (in dollars per share)	691.40	$ 786.79	$ 835.91
Forfeited (in dollars per share)	752.01
Exercised (in dollars per share)	519.17
Outstanding at end of period (in dollars per share)	596.65	$ 588.47
Vested and expected to vest (in dollars per share)	592.93
Exercisable (in dollars per share)	$ 536.47
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average remaining contractual term (in years) - outstanding	5 years 8 months 12 days
Weighted average remaining contractual term - vested and expected to vest	5 years 8 months 12 days
Weighted average remaining contractual term - exercisable	4 years 8 months 12 days
Intrinsic value - outstanding	$ 2,185.9
Intrinsic value - vested and expected to vest	2,178.9
Intrinsic value - exercisable	$ 2,100.0

Long-Term Incentive Plans - Schedule of activity related to performance-based restricted stock units (Details) - Performance-based restricted stock units - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Number of Shares/Units (In millions)
Beginning balance (in shares)	1.4
Vested (in shares)	(1.2)
Ending balance (in shares)	0.2
Weighted-Average Grant Date Fair Value
Weighted-average grant date fair value of awards outstanding (in USD per share)	$ 485.61	$ 247.91
Vested (in dollars of shares)	$ 209.59

Collaboration, License, and Other Agreements (Tables)

12 Months Ended

Dec. 31, 2025

Revenue from Contract with Customer [Abstract]

Schedule of collaboration revenue

Net product sales consist of the following:


		Year Ended December 31,
(In millions)		2025		2024		2023
EYLEA HD®	U.S.	$	1,636.9	$	1,201.1	$	165.8
EYLEA®	U.S.	2,747.8		4,767.1		5,719.6
Total EYLEA HD and EYLEA	U.S.	4,384.7		5,968.2		5,885.4
Libtayo®	U.S.	944.7		787.3		538.8
Libtayo	Rest of world	507.5		429.5		324.3
Total Libtayo	Global	1,452.2		1,216.8		863.1
Praluent®	U.S.	262.5		241.7		182.4
Evkeeza®	U.S.	162.2		125.7		77.3
Inmazeb®	U.S.	37.4		76.8		69.8
Other products	Global	10.1		—		—
		$	6,309.1	$	7,629.2	$	7,078.0

Amounts recognized in the Company's Statements of Operations in connection with its Sanofi collaboration are as follows:


	Statement of Operations Classification	Year Ended December 31,
(In millions)		2025		2024		2023
Regeneron's share of profits	Collaboration revenue	$	5,241.6	$	3,923.5	$	3,136.5
Sales-based milestones earned	Collaboration revenue	$	—	$	—	$	50.0
Reimbursement for manufacturing of commercial supplies	Collaboration revenue	$	642.4	$	607.9	$	613.0
Regeneron's obligation for its share of Sanofi R&D expenses, net of reimbursement of R&D expenses	(R&D expense)	$	(69.5)	$	(46.8)	$	(83.7)
Reimbursement of commercialization-related expenses	Reduction of SG&A expense	$	729.3	$	655.4	$	534.4

Amounts recognized in the Company's Statements of Operations in connection with its Bayer collaboration are as follows:


	Statement of Operations Classification	Year Ended December 31,
(In millions)		2025		2024		2023
Regeneron's share of profits	Collaboration revenue	$	1,282.7	$	1,403.3	$	1,376.4
Reimbursement for manufacturing of commercial supplies	Collaboration revenue	$	139.7	$	95.7	$	111.1
Regeneron's obligation for its share of Bayer R&D expenses, net of reimbursement of R&D expenses	(R&D expense)	$	(20.0)	$	(48.5)	$	(44.0)

Schedule of accounts receivable and deferred revenue information

The following table summarizes contract balances in connection with the Company's Sanofi collaboration:


	As of December 31,
(In millions)	2025		2024
Accounts receivable, net	$	1,610.6	$	1,216.2
Deferred revenue	$	442.3	$	571.7

The following table summarizes contract balances in connection with the Company's Bayer collaboration:


	As of December 31,
(In millions)	2025		2024
Accounts receivable, net	$	287.6	$	349.9
Deferred revenue	$	295.7	$	216.3

Insider Trading Arrangements

3 Months Ended

Dec. 31, 2025

Trading Arrangements, by Individual

Material Terms of Trading Arrangement

As disclosed in the table below, during the three months ended December 31, 2025, certain of our directors and/or executive officers adopted plans for trading arrangements intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) of the Exchange Act.

Name

Position

Date of Plan Adoption

Scheduled End Date of Trading Arrangement(a)

Total Number of Securities to Be Sold Under the Plan

Jason Pitofsky

Senior Vice President, Controller

11/10/2025

5/10/2026

3,261

Arthur F. Ryan

Director

10/31/2025

1/29/2027

1,200

Huda Y. Zoghbi, M.D.

Director

11/20/2025

1/3/2027

2,438

(a) The trading arrangement may expire on an earlier date if and when all transactions under the arrangement are completed

Non-Rule 10b5-1 Arrangement Adopted

false

Rule 10b5-1 Arrangement Terminated

false

Non-Rule 10b5-1 Arrangement Terminated

false

Jason Pitofsky [Member]

Trading Arrangements, by Individual

Name

Jason Pitofsky

Title

Senior Vice President, Controller

Rule 10b5-1 Arrangement Adopted

true

11/10/2025

5/10/2026

181 days

3,261

Arthur F. Ryan [Member]

Trading Arrangements, by Individual

Name

Arthur F. Ryan

Title

Director

Rule 10b5-1 Arrangement Adopted

true

10/31/2025

1/29/2027

455 days

1,200

Huda Y. Zoghbi, M.D. [Member]

Trading Arrangements, by Individual

Name

Huda Y. Zoghbi, M.D.

Title

Director

Rule 10b5-1 Arrangement Adopted

true

11/20/2025

1/3/2027

409 days

2,438

Income Taxes

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Income Taxes

The Company is subject to U.S. federal, state, and foreign income taxes. Components of income before income taxes consist of the following:


	Year Ended December 31,
(In millions)	2025		2024		2023
United States	$	(476.3)	$	(411.3)	$	(362.3)
Foreign	5,707.0		5,191.2		4,561.6
	$	5,230.7	$	4,779.9	$	4,199.3

Components of income tax expense consist of the following:


	Year Ended December 31,
(In millions)	2025		2024		2023
Current:
Federal	$	1,012.3	$	1,092.6	$	667.9
State	19.8		(11.1)		7.7
Foreign	479.1		43.1		407.9
Total current tax expense	1,511.2		1,124.6		1,083.5
Deferred:
Federal	(845.2)		(935.5)		(834.5)
State	(15.5)		(4.9)		(6.5)
Foreign	75.3		183.1		3.2
Total deferred tax benefit	(785.4)		(757.3)		(837.8)
	$	725.8	$	367.3	$	245.7

Cash paid for income taxes, net of refunds received, by jurisdiction for the year ended December 31, 2025 is as follows:


(In millions)	2025
Federal	$	576.5
State	5.3
Foreign:
Ireland	645.2
Other	26.0
	$	1,253.0

Cash paid for income taxes, net of refunds received, were $743.0 million and $870.3 million for the years ended December 31, 2024 and 2023, respectively.

On July 4, 2025, bill H.R. 1, commonly referred to as the "One Big Beautiful Bill Act" or "OBBBA," was signed into law, with certain provisions effective in 2025 and others in 2026. The OBBBA significantly revises U.S. corporate income tax laws by, among other things, restoring the option for immediate expense recognition for U.S.-based research and development expenditures and making permanent the ability to claim first-year bonus depreciation on qualified property. The OBBBA also modifies U.S. taxation on foreign earnings by, among other things, changing the tax rates for Net CFC Tested Income (formerly known as global intangible low-taxed income ("GILTI")) and foreign-derived intangible income (now known as foreign-derived deduction eligible income), modifying the allocation of expenses in calculating foreign tax credits, as well as changing foreign tax credit limitations. As a result of the OBBBA being signed into law, the Company recognized a charge of $44.5 million in 2025 related to the re-measurement of the Company's U.S. net deferred tax assets.

A reconciliation of the U.S. federal statutory tax rate to the Company's effective tax rate for the year ended December 31, 2025 is as follows:


	2025
(In millions, except percent)	Amount		Percent
U.S. federal statutory tax rate	$	1,098.4	21.0	%
Foreign tax effects:
Ireland:
Statutory tax rate difference between Ireland and United States	(480.3)		(9.2)
Domestic top-up tax	120.0		2.3
Other	(5.8)		(0.1)
Other foreign jurisdictions	7.7		0.1
Tax credits:
Research and development and orphan drug tax credits	(133.3)		(2.5)
Effect of cross-border tax laws:
Foreign-derived deduction eligible income	(20.6)		(0.4)
Net CFC tested income ("NCTI"), net of foreign tax credit ("FTC")	(82.7)		(1.6)
Subpart F income, net of FTC	8.3		0.1
Changes in unrecognized tax benefits(a)	124.2		2.4
Effect of changes in tax laws or rates enacted in the current period	44.5		0.9
Nontaxable or nondeductible items:
Stock-based compensation	14.1		0.3
Other permanent differences	27.0		0.5
Other adjustments	4.3		0.1
Effective tax rate	$	725.8	13.9	%

(a) Changes in unrecognized tax benefits for all jurisdictions are aggregated within this category

A reconciliation of the U.S. federal statutory tax rate to the Company's effective tax rate for the years ended December 31, 2024 and 2023 is as follows:


	2024		2023
U.S. federal statutory tax rate	21.0	%	21.0	%
Stock-based compensation	(4.9)		(4.6)
Taxation of non-U.S. operations	(4.0)		(6.6)
Tax credits	(3.5)		(3.2)
Foreign-derived deduction eligible income	(0.8)		(0.3)
Other permanent differences	(0.1)		(0.4)
Effective tax rate	7.7	%	5.9	%

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company's deferred tax assets and liabilities are as follows:


	As of December 31,
(In millions)	2025		2024
Deferred tax assets:
Capitalized research and development expenses	$	3,146.2	$	2,530.2
Deferred compensation	452.0		419.7
Fixed assets and intangible assets	192.6		145.1
Accrued expenses	158.8		185.0
Tax attribute carryforwards	79.6		84.1
Other	49.9		43.0
Total deferred tax assets	4,079.1		3,407.1

Deferred tax liabilities:
Unrealized gains on investments	(1.9)		(93.0)
Net deferred tax assets	$	4,077.2	$	3,314.1

The Company's federal income tax returns for 2019 through 2024 remain open to examination by the IRS. The Company's 2019 and 2020 federal income tax returns are currently under audit by the IRS. In general, the Company's state income tax returns from 2017 to 2024 remain open to examination. The Company's income tax returns outside the United States remain open to examination from 2020 to 2024. The United States and many states generally have statutes of limitation ranging from 3 to 5 years; however, those statutes could be extended due to the Company's tax credit carryforward position. In general, tax authorities have the ability to review income tax returns in which the statute of limitation has previously expired to adjust the tax credits generated in those years.

The following table reconciles the beginning and ending amounts of unrecognized tax benefits:


(In millions)	2025		2024		2023
Balance as of January 1	$	1,313.7	$	696.4	$	542.8
Gross increases related to current year tax positions	401.9		353.5		153.4
Gross (decreases) increases related to prior year tax positions	(43.1)		264.8		3.2
Gross decreases due to settlements and lapse of statutes of limitations	(94.6)		(1.0)		(3.0)
Balance as of December 31	$	1,577.9	$	1,313.7	$	696.4

In 2025, 2024, and 2023, the increases in unrecognized tax benefits primarily related to the Company's calculation of certain tax credits and other items related to the Company's international operations. In 2025, the Company released liabilities for uncertain tax positions in connection with the settlement of the IRS audit of the Company's 2017 and 2018 federal income tax returns. Interest expense related to unrecognized tax benefits was $201.7 million, $165.4 million, and $77.2 million in 2025, 2024, and 2023, respectively.

The amount of net unrecognized tax benefits that, if settled, would impact the effective tax rate is $520.9 million, $635.4 million, and $442.5 million as of December 31, 2025, 2024, and 2023, respectively.

- Definition

The entire disclosure for income tax.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (SX 210.4-08(h)(2))
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147482685/740-10-50-14

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Income Taxes - Schedule of unrecognized tax benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Unrecognized Tax Benefits [Roll Forward]
Balance as of January 1	$ 1,313.7	$ 696.4	$ 542.8
Gross increases related to current year tax positions	401.9	353.5	153.4
Gross decreases related to prior year tax positions	(43.1)
Gross increases related to prior year tax positions		264.8	3.2
Gross decreases due to settlements and lapse of statutes of limitations	(94.6)	(1.0)	(3.0)
Balance as of December 31	$ 1,577.9	$ 1,313.7	$ 696.4

Stockholders' Equity - Schedule of Repurchased Shares (Details) - Share Repurchase Programs - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Equity, Class of Treasury Stock [Line Items]
Number of shares (in shares)	5.6	2.8	2.9
Total cost of shares	$ 3,456.2	$ 2,613.9	$ 2,214.6

Income Taxes - Schedule of cash paid for income taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Tax Paid, by Individual Jurisdiction [Line Items]
Federal	$ 576.5
State	5.3
Total cash paid for income taxes	1,253.0	$ 743.0	$ 870.3
Ireland
Income Tax Paid, by Individual Jurisdiction [Line Items]
Foreign:	645.2
Other
Income Tax Paid, by Individual Jurisdiction [Line Items]
Foreign:	$ 26.0

Long-Term Incentive Plans - Narrative (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Maximum term of awards	10 years
Total intrinsic value - of stock options exercised	$ 193.6	$ 1,682.0	$ 1,096.0
Expected dividend yield	0.49%	0.00%	0.00%
Non-performance based stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-cash stock-based compensation expense	$ 351.9	$ 376.0	$ 357.1
Unrecognized stock-based compensation cost, net of estimated forfeitures	$ 385.8
Weighted average period for recognition of total unrecognized compensation expense (in years)	1 year 8 months 12 days
Restricted stock awards and restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-cash stock-based compensation expense	$ 589.8	$ 554.7	475.9
Unrecognized stock-based compensation cost, net of estimated forfeitures	$ 1,493.0
Weighted average period for recognition of total unrecognized compensation expense (in years)	2 years 3 months 18 days
Awards outstanding (in shares)	3.1	2.5
Weighted-average grant date fair value of awards outstanding (in USD per share)	$ 748.08	$ 760.35
Granted (in shares)	1.4
Vested (in shares)	0.7
Awards forfeited (in shares)	0.1
Performance-based stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-cash stock-based compensation expense	$ 52.0	$ 52.0	$ 52.0
Unrecognized stock-based compensation cost, net of estimated forfeitures	$ 0.0
Awards outstanding (in shares)	0.2	1.4
Weighted-average grant date fair value of awards outstanding (in USD per share)	$ 485.61	$ 247.91
Vested (in shares)	1.2
Performance-based stock options \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Performance-based stock options \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	6 years
Amended & Restated Long-Term Incentive Plan 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance (in shares)	22.3
Number of shares available for future grants (in shares)	12.4

Net Income Per Share

12 Months Ended

Dec. 31, 2025

Earnings Per Share [Abstract]

Net Income Per Share

The calculations of basic and diluted net income per share are as follows:


	Year Ended December 31,
(In millions, except per share data)	2025		2024		2023
Net income - basic and diluted	$	4,504.9	$	4,412.6	$	3,953.6

Weighted average shares - basic	104.6		107.9		106.7
Effect of dilutive securities:
Stock options	1.9		4.8		4.9
Restricted stock awards and restricted stock units	2.1		2.4		2.1
Weighted average shares - diluted	108.6		115.1		113.7

Net income per share - basic	$	43.07	$	40.90	$	37.05
Net income per share - diluted	$	41.48	$	38.34	$	34.77

Shares which have been excluded from diluted per share amounts because their effect would have been antidilutive include the following:


	Year Ended December 31,
(Shares in millions)	2025	2024	2023
Stock options	6.2	1.6	1.8
Restricted stock awards and restricted stock units	0.2	—	—

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Class A Stock	Class A Stock Common Stock
Beginning Balance (in shares) at Dec. 31, 2022		130.4						1.8
Beginning Balance, treasury (in shares) at Dec. 31, 2022						(22.6)
Beginning Balance at Dec. 31, 2022	$ 22,664.0	$ 0.1	$ 9,949.3	$ 23,306.7	$ (238.8)	$ (10,353.3)		$ 0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock for equity awards granted under long-term incentive plans (in shares)		3.5
Issuance of Common Stock for equity awards granted under long-term incentive plans	1,152.2		1,152.2
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations (in shares)		(0.8)
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations	(708.4)		(708.4)
Issuance/distribution of Common Stock for 401(k) Savings Plan (in shares)						0.1
Issuance/distribution of Common Stock for 401(k) Savings Plan	74.1		66.6			$ 7.5
Repurchases of Common Stock (in shares)						(3.0)
Repurchases of Common Stock	(2,214.6)					$ (2,214.6)
Stock-based compensation charges	894.3		894.3
Net income	3,953.6			3,953.6
Other comprehensive income, net of tax	157.9				157.9
Ending Balance (in shares) at Dec. 31, 2023		133.1						1.8
Beginning Ending, treasury (in shares) at Dec. 31, 2023						(25.5)
Ending Balance at Dec. 31, 2023	25,973.1	$ 0.1	11,354.0	27,260.3	(80.9)	$ (12,560.4)		$ 0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock for equity awards granted under long-term incentive plans (in shares)		4.1
Issuance of Common Stock for equity awards granted under long-term incentive plans	1,454.6		1,454.6
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations (in shares)		(1.2)
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations	(1,021.3)		(1,021.3)
Issuance/distribution of Common Stock for 401(k) Savings Plan (in shares)						0.1
Issuance/distribution of Common Stock for 401(k) Savings Plan	78.6		71.7			$ 6.9
Repurchases of Common Stock (in shares)						(2.8)
Repurchases of Common Stock	(2,613.9)					$ (2,613.9)
Stock-based compensation charges	996.9		996.9
Net income	4,412.6			4,412.6
Other comprehensive income, net of tax	$ 73.0				73.0
Ending Balance (in shares) at Dec. 31, 2024		136.0					1.8	1.8
Beginning Ending, treasury (in shares) at Dec. 31, 2024	(28.2)					(28.2)
Ending Balance at Dec. 31, 2024	$ 29,353.6	$ 0.1	12,855.9	31,672.9	(7.9)	$ (15,167.4)		$ 0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock for equity awards granted under long-term incentive plans (in shares)		2.6
Issuance of Common Stock for equity awards granted under long-term incentive plans	637.4		637.4
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations (in shares)		(1.0)
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations	(576.2)		(576.2)
Issuance/distribution of Common Stock for 401(k) Savings Plan (in shares)						0.1
Issuance/distribution of Common Stock for 401(k) Savings Plan	83.0		72.2			$ 10.8
Repurchases of Common Stock (in shares)						(5.6)
Repurchases of Common Stock	(3,456.2)					$ (3,456.2)
Dividends declared	(376.6)		4.1	(380.7)
Stock-based compensation charges	1,001.6		1,001.6
Net income	4,504.9			4,504.9
Other comprehensive income, net of tax	$ 85.4				85.4
Ending Balance (in shares) at Dec. 31, 2025		137.6					1.8	1.8
Beginning Ending, treasury (in shares) at Dec. 31, 2025	(33.7)					(33.7)
Ending Balance at Dec. 31, 2025	$ 31,256.9	$ 0.1	$ 13,995.0	$ 35,797.1	$ 77.5	$ (18,612.8)		$ 0.0

Property, Plant, and Equipment - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 364.8	$ 354.1	$ 328.8
Property, plant, and equipment, net	5,120.4	4,599.7
United States
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, net	4,332.0	3,884.0
Rest of world
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, net	$ 788.0	$ 715.9

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Current assets:
Cash and cash equivalents	$ 3,118.1	$ 2,488.2
Marketable securities	5,487.1	6,524.3
Accounts receivable, net	5,741.1	6,211.9
Inventories	3,200.8	3,087.3
Prepaid expenses and other current assets	474.8	349.2
Total current assets	18,021.9	18,660.9
Marketable securities	10,260.6	8,900.1
Property, plant, and equipment, net	5,120.4	4,599.7
Intangible assets, net	1,257.4	1,148.6
Deferred tax assets	4,077.2	3,314.1
Other noncurrent assets	1,821.2	1,136.0
Total assets	40,558.7	37,759.4
Current liabilities:
Accounts payable	939.0	789.5
Accrued expenses and other current liabilities	2,876.4	2,527.1
Deferred revenue	553.0	627.7
Total current liabilities	4,368.4	3,944.3
Long-term debt	1,985.9	1,984.4
Finance lease liabilities	720.0	720.0
Deferred revenue	208.7	185.7
Other noncurrent liabilities	2,018.8	1,571.4
Total liabilities	9,301.8	8,405.8
Commitments and contingencies
Stockholders' equity:
Preferred Stock, par value $.01 per share; 30.0 shares authorized; shares issued and outstanding - none	0.0	0.0
Additional paid-in capital	13,995.0	12,855.9
Retained earnings	35,797.1	31,672.9
Accumulated other comprehensive income (loss)	77.5	(7.9)
Treasury Stock, at cost; 33.7 shares in 2025 and 28.2 shares in 2024	(18,612.8)	(15,167.4)
Total stockholders' equity	31,256.9	29,353.6
Total liabilities and stockholders' equity	40,558.7	37,759.4
Class A Stock
Stockholders' equity:
Common stock	0.0	0.0
Common Stock
Stockholders' equity:
Common stock	$ 0.1	$ 0.1

Stockholders' Equity

12 Months Ended

Dec. 31, 2025

Equity [Abstract]

Stockholders' Equity

The Company's Restated Certificate of Incorporation, as amended, provides for the issuance of up to 40 million shares of Class A Stock, par value $0.001 per share, and 320 million shares of Common Stock, par value $0.001 per share. Shares of Class A Stock are convertible, at any time, at the option of the holder into shares of Common Stock on a share-for-share basis. Holders of Class A Stock have rights and privileges identical to Common Stockholders except that each share of Class A is entitled to ten votes per share, while each share of Common Stock is entitled to one vote per share. Class A Stock may only be transferred to specified Permitted Transferees, as defined. Under the Company's Restated Certificate of Incorporation, the Company's board of directors is authorized to issue up to 30 million shares of Preferred Stock, in series, with rights, privileges, and qualifications of each series determined by the board of directors.

a. Share Repurchase Programs

The Company's board of directors has authorized share repurchase programs, including a share repurchase program for up to $3.0 billion of the Company's Common Stock which was authorized in February 2025. The programs have no time limit and can be discontinued at any time.


	Year Ended December 31,
(In millions)	2025		2024		2023
Number of shares	5.6		2.8		2.9
Total cost of shares	$	3,456.2	$	2,613.9	$	2,214.6

As of December 31, 2025, $1.486 billion remained available for share repurchases under the Company's share repurchase programs.

b. Dividends

In 2025, the Company's board of directors declared quarterly cash dividends of $0.88 per share on its Common Stock and Class A Stock. Each quarterly dividend was paid to the Company's shareholders in the quarter in which the dividend was declared.

Additionally, in January 2026, the Company's board of directors declared a cash dividend of $0.94 per share on its Common Stock and Class A Stock. The dividend will be payable to the Company's shareholders in March 2026.

- Definition

The entire disclosure for equity.

+ References

+ Details

Income Taxes - Schedule of income before income tax (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income before income taxes, United States	$ (476.3)	$ (411.3)	$ (362.3)
Income before income taxes, Foreign	5,707.0	5,191.2	4,561.6
Income before income taxes	$ 5,230.7	$ 4,779.9	$ 4,199.3

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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+ Details

Statement of Cash Flows - Summary of Non-Cash Investing and Financing Activities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Cash and Cash Equivalents [Abstract]
Accrued capital expenditures	$ 178.8	$ 151.6	$ 75.4
Accrued contingent consideration in connection with acquisitions	$ 58.9	$ 62.7	$ 71.6

Intangible Assets

12 Months Ended

Dec. 31, 2025

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets

Intangible assets, net consist of the following:


		As of December 31,
		2025						2024
(In millions)	Estimated Useful Life	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Acquired product rights - Libtayo	13 years	$	1,635.3	$	(431.9)	$	1,203.4	$	1,347.7	$	(254.3)	$	1,093.4
Other intangibles	8 years	10.0		(8.8)		1.2		10.0		(7.6)		2.4
Acquired in-process research and development	Indefinite	52.8		—		52.8		52.8		—		52.8
		$	1,698.1	$	(440.7)	$	1,257.4	$	1,410.5	$	(261.9)	$	1,148.6

During the years ended December 31, 2025 and 2024, the Company recorded additions to the Libtayo intangible asset related to contingent consideration due to Sanofi in connection with the acquisition of worldwide rights to Libtayo in 2022.

Amortization expense on intangible assets was $178.8 million, $128.9 million, and $92.2 million for the years ended December 31, 2025, 2024, and 2023, respectively.

As of December 31, 2025, assuming no changes in the gross carrying amount of intangible assets, amortization expense is estimated to be approximately $124 million for each of the years ending December 31, 2026 through December 31, 2030.

In addition to the intangible assets summarized in the table above, during the second quarter of 2025, the Company recorded an indefinite-lived intangible asset in connection with the purchase of a U.S. Food and Drug Administration ("FDA") Rare Pediatric Disease Priority Review Voucher ("PRV") from a third party for $155.0 million. During the fourth quarter of 2025, the Company made the decision to utilize the PRV for a regulatory submission, and as a result, the carrying amount was expensed to Research and development.

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2025
Audit Information [Abstract]
Auditor Firm ID	238
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Florham Park, New Jersey

Intangible Assets - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Jun. 30, 2025
Indefinite-Lived Intangible Assets [Line Items]
Amortization expense on intangible assets	$ 178.8	$ 128.9	$ 92.2
Finite-lived intangible asset, expected amortization, year one	124.0
Finite-lived intangible asset, expected amortization, year two	124.0
Finite-lived intangible asset, expected amortization, year three	124.0
Finite-lived intangible asset, expected amortization, year four	124.0
Finite-lived intangible asset, expected amortization, year five	$ 124.0
Priority Review Voucher
Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets				$ 155.0

- Definition

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets.

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+ Details

Product Sales - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Product Sales - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, net	$ 5,741.1	$ 6,211.9
Two Individual Customers \| Accounts receivable \| Customer concentration risk
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk, percentage	87.00%	79.00%
Trade Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, net	$ 3,458.0	$ 4,278.0

- Definition

+ References + Details

Collaboration, License, and Other Agreements - Bayer Narrative (Details) - Bayer $ in Millions	12 Months Ended
	Dec. 31, 2025 USD ($)
Disaggregation of Revenue [Line Items]
Percentage of repayment of development balance out of profits	50.00%
Contingent reimbursement obligation	$ 296

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Leases - Finance lease costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Leases [Abstract]
Operating lease costs	$ 35.8	$ 36.5	$ 19.2
Amortization of finance lease right-of-use assets	14.5	14.5	14.5
Interest on finance lease liabilities	39.1	46.1	45.0
Total finance lease costs	53.6	60.6	59.5
Total lease cost	$ 89.4	$ 97.1	$ 78.7

Statement of Cash Flows (Tables)

12 Months Ended

Dec. 31, 2025

Cash and Cash Equivalents [Abstract]

Schedule of cash and cash equivalents


	December 31,
(In millions)	2025		2024		2023
Cash and cash equivalents	$	3,118.1	$	2,488.2	$	2,730.0
Restricted cash included in Other current assets	5.6		0.8		—
Restricted cash included in Other noncurrent assets	—		—		7.8
Total cash, cash equivalents, and restricted cash shown in the Consolidated Statements of Cash Flows	$	3,123.7	$	2,489.0	$	2,737.8

Schedule of restrictions on cash and cash equivalents


	December 31,
(In millions)	2025		2024		2023
Cash and cash equivalents	$	3,118.1	$	2,488.2	$	2,730.0
Restricted cash included in Other current assets	5.6		0.8		—
Restricted cash included in Other noncurrent assets	—		—		7.8
Total cash, cash equivalents, and restricted cash shown in the Consolidated Statements of Cash Flows	$	3,123.7	$	2,489.0	$	2,737.8

Summary of non-cash investing and financing activities

Cash paid for income taxes, net of refunds received, by jurisdiction for the year ended December 31, 2025 is as follows:


(In millions)	2025
Federal	$	576.5
State	5.3
Foreign:
Ireland	645.2
Other	26.0
	$	1,253.0

Supplemental disclosure of non-cash investing and financing activities


	As of December 31,
(In millions)	2025		2024		2023
Accrued capital expenditures	$	178.8	$	151.6	$	75.4
Accrued contingent consideration in connection with acquisitions	$	58.9	$	62.7	$	71.6

Fair Value Measurements

12 Months Ended

Dec. 31, 2025

Fair Value Disclosures [Abstract]

Fair Value Measurements

•Level 1 - Quoted prices in active markets for identical assets or liabilities

•Level 3 - Significant other unobservable inputs


(In millions)			Fair Value Measurements at Reporting Date
As of December 31, 2025	Fair Value		Level 1		Level 2		Level 3
Assets:
Cash equivalents	$	2,121.6	$	1,127.7	$	993.9	$	—
Available-for-sale debt securities:
Corporate bonds	10,219.5		—		10,219.5		—
U.S. government and government agency obligations	4,367.3		—		4,367.3		—
Commercial paper	541.1		—		541.1		—
Certificates of deposit	265.9		—		265.9		—
Asset-backed securities	242.8		—		242.8		—
Sovereign bonds	76.8		—		76.8		—
Equity securities(a)	34.3		34.3		—		—
Total assets	$	17,869.3	$	1,162.0	$	16,707.3	$	—

Liabilities:
Contingent consideration	$	10.3	$	—	$	—	$	10.3

As of December 31, 2024
Assets:
Cash equivalents	$	1,452.2	$	1,264.2	$	188.0	$	—
Available-for-sale debt securities:
Corporate bonds	8,220.6		—		8,220.6		—
U.S. government and government agency obligations	4,817.0		—		4,817.0		—
Commercial paper	548.7		—		548.7		—
Certificates of deposit	381.1		—		381.1		—
Asset-backed securities	279.3		—		279.3		—
Sovereign bonds	82.4		—		82.4		—
Equity securities(a)	1,095.3		1,095.3		—		—
Total assets	$	16,876.6	$	2,359.5	$	14,517.1	$	—

Liabilities:
Contingent consideration	$	52.3	$	—	$	—	$	52.3

(a) Includes equity securities of $33.3 million and $43.2 million as of December 31, 2025 and 2024, respectively, that are subject to transfer restrictions expiring in April 2026

In addition to the investments summarized in the table above, the Company classified the following investments within Other noncurrent assets:

•As of December 31, 2025 and 2024, $334.0 million and $159.8 million, respectively, of equity securities that do not have a readily determinable fair value. The change in carrying value of such investments was a result of additional purchases.

•As of December 31, 2025 and 2024, equity securities held through ownership interest in an investment fund of $147.5 million and $52.0 million, respectively, which are measured at fair value based on Level 3 inputs. The change in carrying value was primarily the result of additional purchases by the fund.

Amounts recognized in Other income (expense), net, related to the Company's investments in public equity securities consist of the following:


	Year Ended December 31,
(In millions)	2025		2024		2023
Net gains (losses) recognized during the period	$	955.6	$	117.7	$	(235.6)
Less: Net gains recognized on investments sold during the period	966.2		—		6.0
Net unrealized gains (losses) recognized on investments still held as of period end date	$	(10.6)	$	117.7	$	(241.6)

Other Fair Value Disclosures

The fair value of the Company's long-term debt (see Note 10), which was determined based on Level 2 inputs, was estimated to be $1.576 billion and $1.484 billion as of December 31, 2025 and 2024, respectively.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

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-Paragraph 6A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)
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-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 940
-SubTopic 820
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478119/940-820-50-1

+ Details

Product Sales

12 Months Ended

Dec. 31, 2025

Revenue from Contract with Customer [Abstract]

Product Sales

Net product sales consist of the following:


		Year Ended December 31,
(In millions)		2025		2024		2023
EYLEA HD®	U.S.	$	1,636.9	$	1,201.1	$	165.8
EYLEA®	U.S.	2,747.8		4,767.1		5,719.6
Total EYLEA HD and EYLEA	U.S.	4,384.7		5,968.2		5,885.4
Libtayo®	U.S.	944.7		787.3		538.8
Libtayo	Rest of world	507.5		429.5		324.3
Total Libtayo	Global	1,452.2		1,216.8		863.1
Praluent®	U.S.	262.5		241.7		182.4
Evkeeza®	U.S.	162.2		125.7		77.3
Inmazeb®	U.S.	37.4		76.8		69.8
Other products	Global	10.1		—		—
		$	6,309.1	$	7,629.2	$	7,078.0

As of December 31, 2025 and 2024, the Company had $3.458 billion and $4.278 billion, respectively, of trade accounts receivable that were recorded within Accounts receivable, net. As of December 31, 2025 and 2024, two individual customers accounted for 87% and 79%, respectively, of the Company's net trade accounts receivable balances.

The Company had product sales to certain customers that each accounted for more than 10% of total gross product revenue for the years ended December 31, 2025, 2024, and 2023. Sales to each of these customers as a percentage of the Company's total gross product revenue are as follows:


	Year Ended December 31,
	2025		2024		2023
Customer A	50	%	50	%	51	%
Customer B	27	%	24	%	25	%

Revenue from product sales is recorded net of applicable provisions for rebates, chargebacks, and discounts, distribution-related fees, and other sales-related deductions. Accruals for chargebacks and discounts are recorded as a direct reduction to accounts receivable. Accruals for rebates, distribution-related fees, and other sales-related deductions are recorded within accrued liabilities. The following table summarizes the provisions, and credits/payments, for sales-related deductions:


(In millions)	Rebates, Chargebacks, and Discounts		Distribution- Related Fees		Other Sales- Related Deductions		Total
Balance as of December 31, 2022	$	353.9	$	111.4	$	81.5	$	546.8
Provisions	2,074.5		439.2		155.3		2,669.0
Credits/payments	(1,972.7)		(388.3)		(157.5)		(2,518.5)
Balance as of December 31, 2023	455.7		162.3		79.3		697.3
Provisions	2,447.3		462.7		143.0		3,053.0
Credits/payments	(2,363.9)		(497.2)		(128.8)		(2,989.9)
Balance as of December 31, 2024	539.1		127.8		93.5		760.4
Provisions	2,751.7		421.1		119.7		3,292.5
Credits/payments	(2,659.2)		(400.7)		(122.2)		(3,182.1)
Balance as of December 31, 2025	$	631.6	$	148.2	$	91.0	$	870.8

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-9

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-10

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-15

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-13

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org/606/tableOfContent

+ Details

Leases - Amounts recognized in Condensed Consolidated Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Assets:
Finance lease right-of-use assets	$ 576.7	$ 591.2
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Property, plant, and equipment, net	Property, plant, and equipment, net
Operating lease right-of-use assets	$ 245.8	$ 217.4
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other noncurrent assets	Other noncurrent assets
Total lease assets	$ 822.5	$ 808.6
Liabilities:
Finance lease liabilities	720.0	720.0
Operating lease liabilities - current	$ 37.8	$ 30.3
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Accrued expenses and other current liabilities	Accrued expenses and other current liabilities
Operating lease liabilities - noncurrent	$ 229.0	$ 204.1
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other noncurrent liabilities	Other noncurrent liabilities
Total lease liability	$ 986.8	$ 954.4
Accumulated amortization of right-of-use assets	162.9	148.4
Operating lease, right-of-use asset, accumulated amortization	$ 68.8	$ 78.4

Employee Savings Plans	12 Months Ended
Employee Savings Plans	Dec. 31, 2025
Retirement Benefits [Abstract]
Employee Savings Plans	Employee Savings Plans The Company maintains the Regeneron Pharmaceuticals, Inc. 401(k) Savings Plan, as amended and restated (the "Savings Plan"). The terms of the Savings Plan allow U.S. employees (as defined by the Savings Plan) to contribute to the Savings Plan a percentage of their compensation. In addition, the Company may make discretionary contributions, as defined, to the accounts of participants under the Savings Plan. The Company also maintains additional employee savings plans outside the United States, which cover eligible employees. Expenses recognized by the Company related to contributions to such plans were $95.7 million, $90.2 million, and $84.7 million for the years ended December 31, 2025, 2024, and 2023, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (o)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (p)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (q)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 60
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480266/715-60-50-3

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480126/715-20-S99-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480794/715-70-50-1

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480482/715-20-55-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(03)
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-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (l)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/715/tableOfContent

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (r)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (r)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

+ Details

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Schedule of income before income tax

Components of income before income taxes consist of the following:


	Year Ended December 31,
(In millions)	2025		2024		2023
United States	$	(476.3)	$	(411.3)	$	(362.3)
Foreign	5,707.0		5,191.2		4,561.6
	$	5,230.7	$	4,779.9	$	4,199.3

Schedule of components of income tax expense

Components of income tax expense consist of the following:


	Year Ended December 31,
(In millions)	2025		2024		2023
Current:
Federal	$	1,012.3	$	1,092.6	$	667.9
State	19.8		(11.1)		7.7
Foreign	479.1		43.1		407.9
Total current tax expense	1,511.2		1,124.6		1,083.5
Deferred:
Federal	(845.2)		(935.5)		(834.5)
State	(15.5)		(4.9)		(6.5)
Foreign	75.3		183.1		3.2
Total deferred tax benefit	(785.4)		(757.3)		(837.8)
	$	725.8	$	367.3	$	245.7

Schedule of cash paid for income taxes

Cash paid for income taxes, net of refunds received, by jurisdiction for the year ended December 31, 2025 is as follows:


(In millions)	2025
Federal	$	576.5
State	5.3
Foreign:
Ireland	645.2
Other	26.0
	$	1,253.0

Supplemental disclosure of non-cash investing and financing activities


	As of December 31,
(In millions)	2025		2024		2023
Accrued capital expenditures	$	178.8	$	151.6	$	75.4
Accrued contingent consideration in connection with acquisitions	$	58.9	$	62.7	$	71.6

Schedule of effective income tax rate reconciliation

A reconciliation of the U.S. federal statutory tax rate to the Company's effective tax rate for the year ended December 31, 2025 is as follows:


	2025
(In millions, except percent)	Amount		Percent
U.S. federal statutory tax rate	$	1,098.4	21.0	%
Foreign tax effects:
Ireland:
Statutory tax rate difference between Ireland and United States	(480.3)		(9.2)
Domestic top-up tax	120.0		2.3
Other	(5.8)		(0.1)
Other foreign jurisdictions	7.7		0.1
Tax credits:
Research and development and orphan drug tax credits	(133.3)		(2.5)
Effect of cross-border tax laws:
Foreign-derived deduction eligible income	(20.6)		(0.4)
Net CFC tested income ("NCTI"), net of foreign tax credit ("FTC")	(82.7)		(1.6)
Subpart F income, net of FTC	8.3		0.1
Changes in unrecognized tax benefits(a)	124.2		2.4
Effect of changes in tax laws or rates enacted in the current period	44.5		0.9
Nontaxable or nondeductible items:
Stock-based compensation	14.1		0.3
Other permanent differences	27.0		0.5
Other adjustments	4.3		0.1
Effective tax rate	$	725.8	13.9	%

(a) Changes in unrecognized tax benefits for all jurisdictions are aggregated within this category

A reconciliation of the U.S. federal statutory tax rate to the Company's effective tax rate for the years ended December 31, 2024 and 2023 is as follows:


	2024		2023
U.S. federal statutory tax rate	21.0	%	21.0	%
Stock-based compensation	(4.9)		(4.6)
Taxation of non-U.S. operations	(4.0)		(6.6)
Tax credits	(3.5)		(3.2)
Foreign-derived deduction eligible income	(0.8)		(0.3)
Other permanent differences	(0.1)		(0.4)
Effective tax rate	7.7	%	5.9	%

Schedule of deferred tax assets and liabilities

Significant components of the Company's deferred tax assets and liabilities are as follows:


	As of December 31,
(In millions)	2025		2024
Deferred tax assets:
Capitalized research and development expenses	$	3,146.2	$	2,530.2
Deferred compensation	452.0		419.7
Fixed assets and intangible assets	192.6		145.1
Accrued expenses	158.8		185.0
Tax attribute carryforwards	79.6		84.1
Other	49.9		43.0
Total deferred tax assets	4,079.1		3,407.1

Deferred tax liabilities:
Unrealized gains on investments	(1.9)		(93.0)
Net deferred tax assets	$	4,077.2	$	3,314.1

Schedule of unrecognized tax benefits

The following table reconciles the beginning and ending amounts of unrecognized tax benefits:


(In millions)	2025		2024		2023
Balance as of January 1	$	1,313.7	$	696.4	$	542.8
Gross increases related to current year tax positions	401.9		353.5		153.4
Gross (decreases) increases related to prior year tax positions	(43.1)		264.8		3.2
Gross decreases due to settlements and lapse of statutes of limitations	(94.6)		(1.0)		(3.0)
Balance as of December 31	$	1,577.9	$	1,313.7	$	696.4

Segment Information (Tables)

12 Months Ended

Dec. 31, 2025

Segment Reporting [Abstract]

Schedule of significant segment expenses


	Year Ended December 31,
(In millions)	2025		2024		2023
Direct research and development expenses(a)	$	1,758.1	$	1,588.8	$	1,295.6

Indirect research and development expenses:
Payroll and benefits	1,800.8		1,681.7		1,537.0
Lab supplies and other research and development costs	258.2		241.5		210.6
Occupancy and other operating costs	635.4		614.9		518.2
Total indirect research and development expenses	2,694.4		2,538.1		2,265.8

Clinical manufacturing costs	1,391.2		1,195.9		1,053.9

Priority review voucher	155.0		—		—

Reimbursement of research and development expenses by collaborators	(148.5)		(190.8)		(176.3)

Total research and development expenses	$	5,850.2	$	5,132.0	$	4,439.0

(a) Direct research and development expenses are comprised primarily of costs paid to third parties for clinical and product development activities, and the portion of research and development expenses incurred by our collaborators that we are obligated to reimburse

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Payables and Accruals [Abstract]
Accrued payroll and related costs	$ 773.0	$ 640.9
Accrued clinical expenses	357.2	315.7
Accrued sales-related costs	875.6	786.2
Income tax-related costs	351.3	213.2
Other accrued expenses and liabilities	519.3	571.1
Accrued expenses and other current liabilities	$ 2,876.4	$ 2,527.1

Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Interest expense related to unrecognized tax benefits	$ 201.7	$ 165.4	$ 77.2
Unrecognized tax benefits that would impact effective tax rate	520.9	635.4	442.5
Cash paid for income taxes	1,253.0	$ 743.0	$ 870.3
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability	$ 44.5

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Cash flows from operating activities:
Net income	$ 4,504.9	$ 4,412.6	$ 3,953.6
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	543.7	482.9	421.0
Stock-based compensation expense	993.7	982.8	885.0
(Gains) losses on marketable and other securities, net	(946.1)	(118.3)	266.4
Other, net	135.5	36.1	(0.1)
Deferred income taxes	(785.4)	(757.3)	(837.8)
Changes in assets and liabilities:
Decrease (increase) in accounts receivable	498.1	(554.0)	(338.8)
Increase in inventories	(275.3)	(619.7)	(271.7)
Increase in prepaid expenses and other assets	(375.3)	(407.5)	(120.1)
(Decrease) increase in deferred revenue	(51.7)	227.8	37.9
Increase in accounts payable, accrued expenses, and other liabilities	736.8	735.1	598.6
Total adjustments	474.0	7.9	640.4
Net cash provided by operating activities	4,978.9	4,420.5	4,594.0
Cash flows from investing activities:
Purchases of marketable and other securities	(10,958.3)	(16,617.4)	(11,646.0)
Sales or maturities of marketable and other securities	11,546.2	15,027.3	9,442.2
Capital expenditures	(898.4)	(755.9)	(718.6)
Proceeds from sale of property, plant, and equipment	0.0	20.1	0.0
Payments for intangible assets	(315.3)	(125.7)	(207.8)
Acquisitions, net of cash acquired	(3.3)	(16.5)	(54.9)
Net cash used in investing activities	(629.1)	(2,468.1)	(3,185.1)
Cash flows from financing activities:
Proceeds from issuance of Common Stock	635.9	1,465.3	1,145.5
Payments in connection with Common Stock tendered for employee tax obligations	(532.1)	(1,029.1)	(700.6)
Repurchases of Common Stock	(3,438.6)	(2,603.3)	(2,235.0)
Dividends paid	(370.3)	0.0	0.0
Other	(10.3)	(33.4)	0.0
Net cash used in financing activities	(3,715.4)	(2,200.5)	(1,790.1)
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	0.3	(0.7)	(0.4)
Net increase (decrease) in cash, cash equivalents, and restricted cash	634.7	(248.8)	(381.6)
Cash, cash equivalents, and restricted cash at beginning of period	2,489.0	2,737.8	3,119.4
Cash, cash equivalents, and restricted cash at end of period	3,123.7	2,489.0	2,737.8
Supplemental disclosure of cash flow information
Cash paid for interest (net of amounts capitalized)	$ 41.6	$ 52.6	$ 73.1

Net Income Per Share - Schedule of Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income - basic and diluted	$ 4,504.9	$ 4,412.6	$ 3,953.6
Weighted average shares outstanding - basic (in shares)	104.6	107.9	106.7
Effect of dilutive securities:
Weighted average shares - diluted (in shares)	108.6	115.1	113.7
Net income per share - basic (in dollars per share)	$ 43.07	$ 40.90	$ 37.05
Net income per share - diluted (in dollars per share)	$ 41.48	$ 38.34	$ 34.77
Stock options
Effect of dilutive securities:
Effect of dilutive securities (in shares)	1.9	4.8	4.9
Restricted stock awards and restricted stock units
Effect of dilutive securities:
Effect of dilutive securities (in shares)	2.1	2.4	2.1

Business Overview and Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Schedule of estimated useful lives of property, plant, and equipment

The estimated useful lives of property, plant, and equipment are as follows:


Building and improvements						10–50 years
Laboratory and other equipment						3–10 years
Furniture and fixtures						5 years

Property, plant, and equipment, net consists of the following:


	As of December 31,
(In millions)	2025		2024
Building and improvements	$	3,105.9	$	2,573.2
Leasehold improvements	174.4		154.5
Laboratory equipment	1,543.7		1,494.5
Computer equipment and software	522.0		450.8
Furniture, office equipment, and other	219.7		203.8
Land	278.8		288.2
Construction in progress	1,890.2		1,721.6
	7,734.7		6,886.6
Accumulated depreciation and amortization	(2,614.3)		(2,286.9)
	$	5,120.4	$	4,599.7

Summary of presentation in statement of operations of payments to and from collaborators


Nature/Type of Payment						Statement of Operations Presentation
Regeneron's share of profits or losses in connection with commercialization of products						Collaboration revenue
Reimbursement for manufacturing of commercial supplies						Collaboration revenue
Royalties and/or sales-based milestones earned						Collaboration revenue
Reimbursement of Regeneron's research and development expenses						Reduction to Research and development expense
Regeneron's obligation for its share of collaborator's research and development expenses						Research and development expense
Reimbursement of Regeneron's commercialization-related expenses						Reduction to Selling, general, and administrative expense
Regeneron's obligation to pay collaborator for its share of gross profits when Regeneron is deemed to be the principal						Cost of goods sold

Summary of recently issued or adopted accounting standards

Standard/Description

Effective Date

Impact of Adoption on the Company's Financial Statements

January 1, 2025

Adopted prospectively; see Note 15

January 1, 2027 for annual reporting periods and January 1, 2028 for interim reporting periods

Currently evaluating impact

January 1, 2028

Early adopted January 1, 2026; no significant impact expected

Marketable Securities - Schedule of Debt Securities Based on Contractual Maturity Dates (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Investments, Debt and Equity Securities [Abstract]
Maturities within one year	$ 5,487.1	$ 6,524.3
Maturities after one year through five years	10,224.8	7,804.8
Maturities after five years	1.5	0.0
Total	$ 15,713.4	$ 14,329.1

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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+ Details

Statement of Cash Flows - Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 3,118.1	$ 2,488.2	$ 2,730.0
Restricted cash included in Other current assets	5.6	0.8	0.0
Restricted cash included in Other noncurrent assets	0.0	0.0	7.8
Total cash, cash equivalents, and restricted cash shown in the Consolidated Statements of Cash Flows	$ 3,123.7	$ 2,489.0	$ 2,737.8	$ 3,119.4

Collaboration, License, and Other Agreements - Schedule of Contract Balances, Bayer Collaborative (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Disaggregation of Revenue [Line Items]
Accounts receivable, net	$ 5,741.1	$ 6,211.9
Bayer
Disaggregation of Revenue [Line Items]
Accounts receivable, net	287.6	349.9
Deferred revenue	$ 295.7	$ 216.3

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Long-Term Incentive Plans

12 Months Ended

Dec. 31, 2025

Share-Based Payment Arrangement [Abstract]

Long-Term Incentive Plans

The Company has used long-term incentive plans for the purpose of granting equity awards to employees of the Company, including officers, and non-employee members of the Company's board of directors (collectively, "Participants"). The Participants may receive awards as determined by a committee of independent members of the Company's board of directors or, to the extent authorized by such committee with respect to certain Participants, a duly authorized employee (collectively, the "Committee"). The incentive plan currently used by the Company is the Second Amended and Restated Regeneron Pharmaceuticals, Inc. 2014 Long-Term Incentive Plan (the "Second Amended and Restated 2014 Incentive Plan"). It was most recently adopted and approved by the Company's shareholders in 2020. As of the most recent shareholder approval date, the Second Amended and Restated 2014 Incentive Plan provided for the issuance of up to 22.3 million shares of Common Stock in respect of awards. In addition, upon expiration, forfeiture, surrender, exchange, cancellation, or termination of any award previously granted under the Amended and Restated Regeneron Pharmaceuticals, Inc. 2014 Long-Term Incentive Plan (the "Amended and Restated 2014 Incentive Plan"), the Regeneron Pharmaceuticals, Inc. 2014 Long-Term Incentive Plan (the "Original 2014 Incentive Plan"), or the Second Amended and Restated 2000 Long-Term Incentive Plan (the "2000 Incentive Plan"), any shares subject to such award are added to the pool of shares available for grant under the Second Amended and Restated 2014 Incentive Plan.

The awards that may be made under the Second Amended and Restated 2014 Incentive Plan include: (a) non-qualified stock options and incentive stock options, (b) restricted stock awards, (c) shares of phantom stock (also referred to as restricted stock units, which may be time- or performance-based), and (d) other awards. Any award granted may (but is not required to) be subject to vesting based on the attainment by the Company of performance goals pre-established by the Committee.

Stock option awards grant Participants the right to purchase shares of Common Stock at prices determined by the Committee, with exercise prices that are equal to or greater than the average of the high and low market prices of the Company's Common Stock on the date of grant (the "Market Price"). Options vest over a period of time determined by the Committee, generally on a pro rata basis over a four-year period. The Committee also determines the expiration date of each option. The maximum term of options that have been awarded under the 2000 Incentive Plan, the Original 2014 Incentive Plan, the Amended and Restated 2014 Incentive Plan, and the Second Amended and Restated 2014 Incentive Plan (collectively, the "Incentive Plans") is ten years.

Restricted stock awards grant Participants shares of restricted Common Stock. Such shares are nontransferable for a period determined by the Committee ("vesting period"). Should employment terminate, as specified in the Incentive Plans, except as determined by the Committee in its discretion and subject to the applicable Incentive Plan documents, the ownership of any unvested restricted stock awards will be transferred to the Company.

Phantom stock awards provide the Participant the right to receive Common Stock or an amount of cash based on the value of the Common Stock at a future date. The award is subject to such restrictions, if any, as the Committee may impose at the date of grant or thereafter, including a specified period of employment or the achievement of performance goals. Time-based restricted stock units and performance-based restricted stock units are each a type of phantom stock award permitted under the Second Amended and Restated 2014 Incentive Plan.

The Incentive Plans contain provisions that allow for the Committee to provide for the immediate vesting of awards upon a change in control of the Company, as defined in the Incentive Plans.

As of December 31, 2025, there were 12.4 million shares available for future grants under the Second Amended and Restated 2014 Incentive Plan.

a. Stock Options

The table below summarizes the activity related to stock option awards under the Company's Incentive Plans during 2025.


		Number of Shares (In millions)	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term	Intrinsic Value (In millions)
Outstanding as of December 31, 2024		12.7	$	588.47
2025:	Granted	0.7	$	691.40
	Forfeited	(0.4)	$	752.01
	Exercised	(1.2)	$	519.17
Outstanding as of December 31, 2025		11.8	$	596.65	5.7 years	$	2,185.9

Vested and expected to vest as of December 31, 2025		11.5	$	592.93	5.7 years	$	2,178.9

Exercisable as of December 31, 2025		8.7	$	536.47	4.7 years	$	2,100.0

The Company satisfies stock option exercises with newly issued shares of the Company's Common Stock. The total intrinsic value of stock options exercised during 2025, 2024, and 2023 was $193.6 million, $1.682 billion, and $1.096 billion, respectively. The intrinsic value represents the amount by which the market price of the underlying stock exceeds the exercise price of an option.

The table below summarizes the weighted-average exercise prices and weighted-average grant-date fair values of options granted during the years ended December 31, 2025, 2024, and 2023.


	Number of Options Granted (In millions)	Weighted-Average Exercise Price		Weighted-Average Fair Value
2025:
Exercise price equal to Market Price	0.7	$	691.40	$	206.58
2024:
Exercise price equal to Market Price	1.9	$	786.79	$	235.32
2023:
Exercise price equal to Market Price	1.6	$	835.91	$	264.37

For the years ended December 31, 2025, 2024, and 2023, the Company recognized $351.9 million, $376.0 million, and $357.1 million, respectively, of stock-based compensation expense related to stock option awards (net of amounts capitalized as inventory, which were not material for each of the three years). As of December 31, 2025, there was $385.8 million of stock-based compensation cost related to unvested stock options, net of estimated forfeitures, which had not yet been recognized. The Company expects to recognize this compensation cost over a weighted-average period of 1.7 years.

Fair Value Assumptions:

The following table summarizes the weighted average values of the assumptions used in computing the fair value of option grants during 2025, 2024, and 2023.


	2025		2024		2023
Expected volatility	26	%	25	%	26	%
Expected lives from grant date	5.3 years		5.0 years		5.1 years
Expected dividend yield	0.49	%	0	%	0	%
Risk-free interest rate	3.79	%	4.11	%	4.29	%

Expected volatility has been estimated based on actual movements in the Company's stock price over the most recent historical periods equivalent to the options' expected lives. Expected lives are principally based on the Company's historical exercise experience with previously issued option grants. Expected dividend yield is based on the Company's historical practice and expectation of future dividend payments. During 2024 and 2023, the expected dividend yield was zero as the Company had not paid dividends nor did it expect to at the time of option grants. The risk-free interest rates are based on quoted U.S. Treasury rates for securities with maturities approximating the options' expected lives.

b. Restricted Stock Awards and Time-Based Restricted Stock Units


		Number of Shares/Units (In millions)	Weighted-Average Grant Date Fair Value
Unvested as of December 31, 2024		2.5	$	760.35
2025:	Granted	1.4	$	718.94
	Vested	(0.7)	$	734.49
	Forfeited	(0.1)	$	753.77
Unvested as of December 31, 2025		3.1	$	748.08

For the years ended December 31, 2025, 2024, and 2023, the Company recognized $589.8 million, $554.7 million, and $475.9 million, respectively, of stock-based compensation expense related to restricted stock (net of amounts capitalized as inventory, which were not material for each of the three years). As of December 31, 2025, there was $1.493 billion of stock-based compensation cost related to unvested restricted stock which had not yet been recognized. The Company expects to recognize this compensation cost over a weighted-average period of 2.3 years.

c. Performance-based Restricted Stock Units

Performance-based restricted stock units ("PSUs") have been granted to certain members of senior management of the Company. PSUs may be earned based upon the attainment of pre-established performance criteria, which may include a market and/or performance condition. Depending on the terms of the PSUs and the outcome of the pre-established performance criteria, a recipient may ultimately earn the target number of PSUs granted or a specified multiple thereof at the end of a 4–6 year vesting period, as applicable.

The table below summarizes activity related to PSUs during 2025. The number of unvested PSUs represents the maximum number of units that are eligible to be earned.


		Number of Shares/Units (In millions)	Weighted-Average Grant Date Fair Value
Unvested as of December 31, 2024		1.4	$	247.91
2025:	Vested	(1.2)	$	209.59
Unvested as of December 31, 2025		0.2	$	485.61

For each of the years ended December 31, 2025, 2024, and 2023 the Company recognized $52.0 million of stock-based compensation expense related to PSUs. As of December 31, 2025, there was no stock-based compensation cost expected to be recognized related to unvested PSUs.

Collaboration, License, and Other Agreements - Schedule of Collaboration Revenue Earned From Bayer (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Revenues	$ 14,342.9	$ 14,202.0	$ 13,117.2
Bayer \| Rest of world \| Collaboration revenue \| Regeneron's share of profits
Disaggregation of Revenue [Line Items]
Revenues	1,282.7	1,403.3	1,376.4
Bayer \| Rest of world \| Collaboration revenue \| Reimbursement for manufacturing of commercial supplies
Disaggregation of Revenue [Line Items]
Revenues	139.7	95.7	111.1
Bayer \| Rest of world \| (R&D expense) \| Regeneron's obligation for its share of Bayer R&D expenses, net of reimbursement of R&D expenses
Disaggregation of Revenue [Line Items]
Revenues	$ (20.0)	$ (48.5)	$ (44.0)

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details

Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2025

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of intangible assets

Intangible assets, net consist of the following:


		As of December 31,
		2025						2024
(In millions)	Estimated Useful Life	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Acquired product rights - Libtayo	13 years	$	1,635.3	$	(431.9)	$	1,203.4	$	1,347.7	$	(254.3)	$	1,093.4
Other intangibles	8 years	10.0		(8.8)		1.2		10.0		(7.6)		2.4
Acquired in-process research and development	Indefinite	52.8		—		52.8		52.8		—		52.8
		$	1,698.1	$	(440.7)	$	1,257.4	$	1,410.5	$	(261.9)	$	1,148.6

Marketable Securities - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Interest income	$ 716.8	$ 711.4	$ 495.9

Inventories - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Inventories - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Inventory Disclosure [Abstract]
Inventory write-downs and reserves	$ 172.9	$ 126.3	$ 102.3

Inventories (Tables)

12 Months Ended

Dec. 31, 2025

Inventory Disclosure [Abstract]

Schedule of inventory

Inventories consist of the following:


	As of December 31,
(In millions)	2025		2024
Raw materials	$	641.5	$	879.5
Work-in-process	1,641.6		1,342.3
Finished goods	190.2		139.8
Deferred costs	727.5		725.7
	$	3,200.8	$	3,087.3

Income Taxes - Schedule of deferred tax assets and liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Deferred tax assets:
Capitalized research and development expenses	$ 3,146.2	$ 2,530.2
Deferred compensation	452.0	419.7
Accrued expenses	158.8	185.0
Fixed assets and intangible assets	192.6	145.1
Tax attribute carryforwards	79.6	84.1
Other	49.9	43.0
Total deferred tax assets	4,079.1	3,407.1
Deferred tax liabilities:
Unrealized gains on investments	(1.9)	(93.0)
Net deferred tax assets	$ 4,077.2	$ 3,314.1

Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets, net	$ 1,257.4	$ 1,148.6
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount	1,698.1	1,410.5
Accumulated Amortization	(440.7)	(261.9)
Acquired in-process research and development
Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 52.8	52.8
Acquired product rights - Libtayo
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life (in years)	13 years
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount	$ 1,635.3	1,347.7
Accumulated Amortization	(431.9)	(254.3)
Net Carrying Amount	$ 1,203.4	1,093.4
Other intangibles
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life (in years)	8 years
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount	$ 10.0	10.0
Accumulated Amortization	(8.8)	(7.6)
Net Carrying Amount	$ 1.2	$ 2.4

Leases - Leases Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2025	Mar. 27, 2023	Mar. 31, 2017
Lessee, Lease, Description [Line Items]
Finance lease, liability	$ 720.0
Finance lease, renewal term		5 years
Laboratory and Office Facilities
Lessee, Lease, Description [Line Items]
Finance lease, liability			$ 720.0

Collaboration, License, and Other Agreements - Sanofi, Antibody Narrative (Details) - Sanofi Collaboration Agreement, Antibody - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Percentage of quarterly profits require to be paid for reimbursement of development costs	20.00%
Contingent reimbursement obligation	$ 595.0
Starting share of profits outside the United States, based on sales, for collaborating party	65.00%
Starting share of profits outside the United States, based on sales, for company	35.00%
Ending share of profits outside the United States, based on sales, for collaborating party	55.00%
Ending share of profits outside the United States, based on sales, for company	45.00%
Sales Milestone Five
Disaggregation of Revenue [Line Items]
Revenue, remaining performance obligation, variable consideration amount		$ 50.0
Levels of twelve month sales at which sales milestone payments would be received		$ 3,000.0
Period for achieving sales target for milestone payment, rolling basis		12 months
Minimum
Disaggregation of Revenue [Line Items]
Percentage of trial costs required to be funded by collaborating party	80.00%
Percentage of quarterly profits require to be paid for reimbursement of development costs	30.00%
Maximum
Disaggregation of Revenue [Line Items]
Percentage of trial costs required to be funded by collaborating party	100.00%
Percentage of quarterly profits require to be paid for reimbursement of development costs	50.00%

Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2025

Investments, Debt and Equity Securities [Abstract]

Available-for-sale debt securities

The following tables summarize the Company's investments in available-for-sale debt securities:


(In millions)	Amortized		Unrealized				Fair
As of December 31, 2025	Cost Basis		Gains		Losses		Value
Corporate bonds	$	10,141.0	$	80.9	$	(2.4)	$	10,219.5
U.S. government and government agency obligations	4,352.2		15.2		(0.1)		4,367.3
Commercial paper	540.8		0.3		—		541.1
Certificates of deposit	265.7		0.2		—		265.9
Asset-backed securities	241.4		1.4		—		242.8
Sovereign bonds	76.3		0.5		—		76.8
	$	15,617.4	$	98.5	$	(2.5)	$	15,713.4

As of December 31, 2024
Corporate bonds	$	8,226.9	$	25.1	$	(31.4)	$	8,220.6
U.S. government and government agency obligations	4,820.5		3.4		(6.9)		4,817.0
Commercial paper	548.3		0.4		—		548.7
Certificates of deposit	380.6		0.5		—		381.1
Asset-backed securities	279.0		0.6		(0.3)		279.3
Sovereign bonds	82.7		0.1		(0.4)		82.4
	$	14,338.0	$	30.1	$	(39.0)	$	14,329.1

Marketable securities, based on contractual maturity dates

The fair values of available-for-sale debt securities by contractual maturity consist of the following:


	As of December 31,
(In millions)	2025		2024
Maturities within one year	$	5,487.1	$	6,524.3
Maturities after one year through five years	10,224.8		7,804.8
Maturities after five years	1.5		—
	$	15,713.4	$	14,329.1

- Definition

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

+ Details

Net Income Per Share (Tables)

12 Months Ended

Dec. 31, 2025

Earnings Per Share [Abstract]

Basic and diluted net income (loss) per share

The calculations of basic and diluted net income per share are as follows:


	Year Ended December 31,
(In millions, except per share data)	2025		2024		2023
Net income - basic and diluted	$	4,504.9	$	4,412.6	$	3,953.6

Weighted average shares - basic	104.6		107.9		106.7
Effect of dilutive securities:
Stock options	1.9		4.8		4.9
Restricted stock awards and restricted stock units	2.1		2.4		2.1
Weighted average shares - diluted	108.6		115.1		113.7

Net income per share - basic	$	43.07	$	40.90	$	37.05
Net income per share - diluted	$	41.48	$	38.34	$	34.77

Antidilutive securities

Shares which have been excluded from diluted per share amounts because their effect would have been antidilutive include the following:


	Year Ended December 31,
(Shares in millions)	2025	2024	2023
Stock options	6.2	1.6	1.8
Restricted stock awards and restricted stock units	0.2	—	—