Legal Matters	12 Months Ended
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.

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.

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.

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.

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.

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.

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.

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:

◦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).

◦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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.