Regeneron dropped its suit over the drug it leans on most. Dupixent's split didn't change.
Sanofi will pay Regeneron $1 billion up front to share four new antibodies, and the two settled their litigation, they said Oct. 1. Neither their release nor Regeneron's 8-K says whether it got the Dupixent information it sued for.
KeyVex News··6 min readFact-checked against 6 public recordsKeyVex News··6 min readFact-checked against 6 public records
REGN$738.72▲ 1.7%Close, Oct. 6. Prices from Tiingo.The short versionTap to readTap to close
- Dupixent is the drug Regeneron leans on most. Revenue from the Sanofi partnership, mostly its share of Dupixent profits, was 48% of Regeneron's revenue in the first half of 2026.
- Regeneron sued Sanofi in 2024, saying it lacked full access to information on Dupixent's commercial business. The case was dismissed Oct. 5. Neither the deal release nor Regeneron's filing says whether it got that access.
- Nearly a quarter of investors surveyed by RBC Capital were seeking better Dupixent economics, StockStory reported, citing Investing.com. The Dupixent profit split did not change.
- On the four new antibodies, development costs are split equally up to a budget cap. Above it, Regeneron pays, with some rights to recoup later. Regeneron carries any overrun unless and until it recoups it.
- Regeneron says it will file the full agreement with its quarterly report for the three months that ended Sept. 30. The 8-K doesn't give the cap's size.
The deal: Sanofi will pay Regeneron Pharmaceuticals $1 billion up front, plus up to $7 billion in payments tied to development, regulatory and sales goals, to develop four new antibodies together, the companies said Oct. 1.Release8-K The same release said they had settled their earlier litigation, and that the existing profit-sharing agreement on Dupixent "will not change."Release
The lawsuit: The litigation was Regeneron's. It sued Sanofi in federal court in New York on Nov. 18, 2024, saying Sanofi had broken their 2009 agreement by not giving it full access to material information on the commercialization of Dupixent and other products in the collaboration, and concerning its audit rights.10-Q On March 17, 2026, a judge refused Sanofi's request to throw the case out.10-Q The two sides jointly asked to drop it on Oct. 2, and the judge signed off on Oct. 5.Docket Regeneron's 8-K, the form a company files to report a major event, said before the market opened on Oct. 6 that this was the suit it had agreed to dismiss.8-K
Why it matters: The suit was about information on the drug Regeneron leans on most. Its Sanofi collaboration revenue, "most of which" is its share of Dupixent profits, was 32% of its revenue in 2024 and 41% in 2025. In the first half of 2026 it was 48%.10-K10-Q Neither the release nor the 8-K says whether Sanofi agreed to give Regeneron the access it sued for.8-KRelease
Regeneron's stock and the lawsuit's key datesDaily close, Nov. 1, 2024 to Oct. 6, 2026 ▼ 12.4%Show chartHide chart
- 1Nov. 18, 2024 Regeneron sues Sanofi. In federal court in New York, over access to Dupixent's commercial information and its audit rights. The stock closes at $762.00.
- 2March 17, 2026 The court denies Sanofi's motion to dismiss. The stock closes at $759.05.
- 3July 30, 2026 Regeneron's second-quarter 10-Q. Revenue from the Sanofi partnership was 48% of Regeneron's revenue in the first half. The stock closes at $738.34.
- 4Oct. 1, 2026 The deal is announced. $1 billion up front for four new antibodies; the companies say they have settled. The stock closes at $734.81, down 3.1%.
- 5Oct. 5, 2026 The court so-orders the dismissal. The stock closes at $726.47.
- 6Oct. 6, 2026 Regeneron's 8-K, before the open. The terms, including the budget cap. The stock closes at $738.72.
View the data (482 trading days)
| Date | Close | Day change |
|---|---|---|
| 2026-10-06 | $738.72 | +1.7% |
| 2026-10-05 | $726.47 | −1.2% |
| 2026-10-02 | $735.20 | +0.1% |
| 2026-10-01 | $734.81 | −3.1% |
| 2026-09-30 | $758.27 | +1.0% |
| 2026-09-29 | $750.51 | −0.2% |
| 2026-09-28 | $752.25 | −4.5% |
| 2026-09-25 | $788.04 | −1.0% |
| 2026-09-24 | $796.02 | −0.7% |
| 2026-09-23 | $801.82 | −0.3% |
| 2026-09-22 | $803.90 | +0.7% |
| 2026-09-21 | $798.17 | +1.7% |
| 2026-09-18 | $784.85 | −0.6% |
| 2026-09-17 | $789.45 | +1.9% |
| 2026-09-16 | $774.61 | +0.1% |
| 2026-09-15 | $774.11 | −2.5% |
| 2026-09-14 | $793.74 | +1.6% |
| 2026-09-11 | $781.49 | −1.5% |
| 2026-09-10 | $793.26 | −1.8% |
| 2026-09-09 | $807.65 | −0.3% |
| 2026-09-08 | $810.31 | −2.1% |
| 2026-09-04 | $827.72 | −1.9% |
| 2026-09-03 | $843.47 | −1.0% |
| 2026-09-02 | $852.03 | +3.4% |
| 2026-09-01 | $823.82 | +3.1% |
| 2026-08-31 | $799.08 | +0.6% |
| 2026-08-28 | $794.19 | −1.7% |
| 2026-08-27 | $807.71 | −0.9% |
| 2026-08-26 | $814.79 | −2.3% |
| 2026-08-25 | $833.56 | +0.6% |
| 2026-08-24 | $828.50 | −0.7% |
| 2026-08-21 | $834.04 | +0.9% |
| 2026-08-20 | $826.64 | −1.7% |
| 2026-08-19 | $840.84 | +3.8% |
| 2026-08-18 | $810.24 | +0.5% |
| 2026-08-17 | $805.93 | +0.3% |
| 2026-08-14 | $803.48 | −0.3% |
| 2026-08-13 | $805.97 | +1.0% |
| 2026-08-12 | $797.99 | +0.1% |
| 2026-08-11 | $797.00 | −1.4% |
| 2026-08-10 | $808.05 | +3.0% |
| 2026-08-07 | $784.36 | +1.6% |
| 2026-08-06 | $772.11 | +0.5% |
| 2026-08-05 | $768.58 | +1.0% |
| 2026-08-04 | $760.66 | +0.2% |
| 2026-08-03 | $759.24 | −0.4% |
| 2026-07-31 | $762.63 | +3.3% |
| 2026-07-30 | $738.34 | +6.2% |
| 2026-07-29 | $695.42 | 0.0% |
| 2026-07-28 | $695.18 | +4.2% |
| 2026-07-27 | $667.17 | +1.7% |
| 2026-07-24 | $656.01 | +0.6% |
| 2026-07-23 | $651.91 | +0.1% |
| 2026-07-22 | $651.18 | −3.6% |
| 2026-07-21 | $675.19 | +0.5% |
| 2026-07-20 | $672.15 | −0.7% |
| 2026-07-17 | $676.69 | −0.3% |
| 2026-07-16 | $678.94 | +2.2% |
| 2026-07-15 | $664.45 | +1.3% |
| 2026-07-14 | $656.12 | −1.1% |
| 2026-07-13 | $663.09 | −0.2% |
| 2026-07-10 | $664.52 | −0.5% |
| 2026-07-09 | $667.95 | +0.8% |
| 2026-07-08 | $662.88 | −2.0% |
| 2026-07-07 | $676.23 | +4.1% |
| 2026-07-06 | $649.81 | −0.7% |
| 2026-07-02 | $654.27 | +4.7% |
| 2026-07-01 | $624.72 | +0.2% |
| 2026-06-30 | $623.54 | −1.3% |
| 2026-06-29 | $631.81 | −0.2% |
| 2026-06-26 | $632.90 | +2.1% |
| 2026-06-25 | $620.14 | −0.5% |
| 2026-06-24 | $623.43 | +0.9% |
| 2026-06-23 | $618.03 | +0.9% |
| 2026-06-22 | $612.50 | +0.4% |
| 2026-06-18 | $609.94 | +0.3% |
| 2026-06-17 | $607.93 | −1.1% |
| 2026-06-16 | $614.73 | 0.0% |
| 2026-06-15 | $614.98 | +0.5% |
| 2026-06-12 | $612.14 | +0.1% |
| 2026-06-11 | $611.48 | +1.6% |
| 2026-06-10 | $601.65 | −2.4% |
| 2026-06-09 | $616.18 | +0.8% |
| 2026-06-08 | $611.34 | −3.8% |
| 2026-06-05 | $635.45 | +1.1% |
| 2026-06-04 | $628.73 | +1.6% |
| 2026-06-03 | $618.95 | +2.7% |
| 2026-06-02 | $602.92 | +0.4% |
| 2026-06-01 | $600.66 | −2.3% |
| 2026-05-29 | $614.78 | −1.1% |
| 2026-05-28 | $621.52 | −1.0% |
| 2026-05-27 | $627.74 | −1.1% |
| 2026-05-26 | $634.62 | −0.7% |
| 2026-05-22 | $638.88 | −0.6% |
| 2026-05-21 | $642.59 | −1.1% |
| 2026-05-20 | $649.76 | +3.1% |
| 2026-05-19 | $630.30 | +0.1% |
| 2026-05-18 | $629.68 | −9.8% |
| 2026-05-15 | $698.25 | −2.1% |
| 2026-05-14 | $712.87 | −1.0% |
| 2026-05-13 | $719.88 | −0.5% |
| 2026-05-12 | $723.41 | +1.5% |
| 2026-05-11 | $712.77 | −0.3% |
| 2026-05-08 | $714.89 | +0.8% |
| 2026-05-07 | $709.10 | −1.7% |
| 2026-05-06 | $721.05 | +2.7% |
| 2026-05-05 | $702.27 | −1.0% |
| 2026-05-04 | $709.21 | +1.1% |
| 2026-05-01 | $701.42 | −0.8% |
| 2026-04-30 | $707.06 | +3.0% |
| 2026-04-29 | $686.36 | −6.2% |
| 2026-04-28 | $731.77 | −1.7% |
| 2026-04-27 | $744.44 | −0.9% |
| 2026-04-24 | $751.57 | −1.9% |
| 2026-04-23 | $766.02 | +2.6% |
| 2026-04-22 | $746.58 | −0.1% |
| 2026-04-21 | $747.36 | −0.3% |
| 2026-04-20 | $749.41 | −0.2% |
| 2026-04-17 | $750.57 | +0.6% |
| 2026-04-16 | $746.00 | −1.1% |
| 2026-04-15 | $753.93 | −0.2% |
| 2026-04-14 | $755.51 | +1.2% |
| 2026-04-13 | $746.46 | −0.3% |
| 2026-04-10 | $748.87 | −2.5% |
| 2026-04-09 | $767.85 | −1.0% |
| 2026-04-08 | $775.53 | +2.0% |
| 2026-04-07 | $760.27 | −0.4% |
| 2026-04-06 | $763.04 | +0.2% |
| 2026-04-02 | $761.85 | −2.0% |
| 2026-04-01 | $777.25 | +0.6% |
| 2026-03-31 | $772.64 | +3.1% |
| 2026-03-30 | $749.29 | +1.6% |
| 2026-03-27 | $737.71 | −2.5% |
| 2026-03-26 | $756.73 | +1.0% |
| 2026-03-25 | $749.47 | +1.0% |
| 2026-03-24 | $741.69 | +0.7% |
| 2026-03-23 | $736.53 | +0.5% |
| 2026-03-20 | $732.87 | −0.6% |
| 2026-03-19 | $737.45 | −0.9% |
| 2026-03-18 | $744.12 | −2.0% |
| 2026-03-17 | $759.05 | +0.3% |
| 2026-03-16 | $756.91 | +1.5% |
| 2026-03-13 | $745.77 | −0.1% |
| 2026-03-12 | $746.61 | −3.6% |
| 2026-03-11 | $774.66 | +0.3% |
| 2026-03-10 | $772.03 | −1.2% |
| 2026-03-09 | $781.60 | +2.9% |
| 2026-03-06 | $759.86 | −0.7% |
| 2026-03-05 | $764.93 | −2.9% |
| 2026-03-04 | $787.50 | +2.7% |
| 2026-03-03 | $766.66 | −3.1% |
| 2026-03-02 | $790.81 | +1.2% |
| 2026-02-27 | $781.67 | +1.4% |
| 2026-02-26 | $770.79 | −1.7% |
| 2026-02-25 | $784.28 | +1.6% |
| 2026-02-24 | $772.19 | −1.9% |
| 2026-02-23 | $787.04 | +0.9% |
| 2026-02-20 | $779.67 | −0.3% |
| 2026-02-19 | $782.38 | −1.2% |
| 2026-02-18 | $792.16 | −0.2% |
| 2026-02-17 | $793.53 | −1.2% |
| 2026-02-13 | $803.17 | +2.5% |
| 2026-02-12 | $783.65 | +0.6% |
| 2026-02-11 | $778.97 | +3.2% |
| 2026-02-10 | $754.91 | −3.3% |
| 2026-02-09 | $780.28 | −0.7% |
| 2026-02-06 | $785.51 | +2.5% |
| 2026-02-05 | $766.63 | −1.1% |
| 2026-02-04 | $775.06 | +2.1% |
| 2026-02-03 | $759.18 | +0.6% |
| 2026-02-02 | $755.02 | +1.8% |
| 2026-01-30 | $741.45 | −1.1% |
| 2026-01-29 | $749.44 | −0.2% |
| 2026-01-28 | $751.13 | −2.6% |
| 2026-01-27 | $771.25 | +1.1% |
| 2026-01-26 | $762.65 | +1.2% |
| 2026-01-23 | $753.55 | −0.3% |
| 2026-01-22 | $755.51 | +0.8% |
| 2026-01-21 | $749.33 | +2.1% |
| 2026-01-20 | $733.78 | +0.1% |
| 2026-01-16 | $733.04 | −1.2% |
| 2026-01-15 | $741.92 | −1.6% |
| 2026-01-14 | $754.14 | −0.6% |
| 2026-01-13 | $758.91 | −1.2% |
| 2026-01-12 | $768.00 | −3.6% |
| 2026-01-09 | $796.55 | −0.6% |
| 2026-01-08 | $801.01 | −1.4% |
| 2026-01-07 | $812.27 | +4.6% |
| 2026-01-06 | $776.54 | +1.7% |
| 2026-01-05 | $763.23 | −1.7% |
| 2026-01-02 | $776.31 | +0.6% |
| 2025-12-31 | $771.87 | −0.3% |
| 2025-12-30 | $773.94 | −0.8% |
| 2025-12-29 | $780.50 | −0.6% |
| 2025-12-26 | $784.97 | +0.2% |
| 2025-12-24 | $783.71 | −0.2% |
| 2025-12-23 | $785.17 | +0.7% |
| 2025-12-22 | $779.36 | +1.5% |
| 2025-12-19 | $767.96 | +2.6% |
| 2025-12-18 | $748.71 | −0.1% |
| 2025-12-17 | $749.79 | +0.5% |
| 2025-12-16 | $746.36 | −0.8% |
| 2025-12-15 | $752.62 | +1.5% |
| 2025-12-12 | $741.29 | −0.7% |
| 2025-12-11 | $746.80 | +2.8% |
| 2025-12-10 | $726.21 | +4.9% |
| 2025-12-09 | $692.58 | −1.5% |
| 2025-12-08 | $703.26 | −2.1% |
| 2025-12-05 | $718.36 | −0.6% |
| 2025-12-04 | $722.80 | −0.1% |
| 2025-12-03 | $723.67 | −2.5% |
| 2025-12-02 | $742.00 | −1.1% |
| 2025-12-01 | $750.11 | −3.9% |
| 2025-11-28 | $780.19 | −0.6% |
| 2025-11-26 | $784.61 | −0.3% |
| 2025-11-25 | $787.32 | +3.4% |
| 2025-11-24 | $761.45 | +0.7% |
| 2025-11-21 | $755.90 | +2.6% |
| 2025-11-20 | $737.00 | +4.9% |
| 2025-11-19 | $702.75 | −3.1% |
| 2025-11-18 | $725.34 | +3.0% |
| 2025-11-17 | $704.31 | +1.6% |
| 2025-11-14 | $693.50 | −0.2% |
| 2025-11-13 | $694.99 | +1.9% |
| 2025-11-12 | $681.72 | +1.1% |
| 2025-11-11 | $674.55 | +3.0% |
| 2025-11-10 | $654.74 | −0.4% |
| 2025-11-07 | $657.53 | +1.6% |
| 2025-11-06 | $646.87 | +0.4% |
| 2025-11-05 | $644.19 | +2.6% |
| 2025-11-04 | $628.00 | −2.2% |
| 2025-11-03 | $642.25 | −1.5% |
| 2025-10-31 | $651.80 | −0.3% |
| 2025-10-30 | $654.04 | +0.2% |
| 2025-10-29 | $652.91 | −0.2% |
| 2025-10-28 | $654.48 | +11.8% |
| 2025-10-27 | $585.31 | +1.3% |
| 2025-10-24 | $577.95 | +0.4% |
| 2025-10-23 | $575.69 | −1.5% |
| 2025-10-22 | $584.74 | +0.9% |
| 2025-10-21 | $579.34 | +0.4% |
| 2025-10-20 | $576.77 | −0.2% |
| 2025-10-17 | $578.05 | +1.6% |
| 2025-10-16 | $569.17 | −1.3% |
| 2025-10-15 | $576.42 | +0.7% |
| 2025-10-14 | $572.60 | +2.7% |
| 2025-10-13 | $557.73 | −1.2% |
| 2025-10-10 | $564.63 | −0.9% |
| 2025-10-09 | $569.90 | +1.1% |
| 2025-10-08 | $563.86 | −3.3% |
| 2025-10-07 | $583.24 | −0.4% |
| 2025-10-06 | $585.48 | −2.4% |
| 2025-10-03 | $600.00 | 0.0% |
| 2025-10-02 | $600.00 | 0.0% |
| 2025-10-01 | $599.94 | +6.7% |
| 2025-09-30 | $562.27 | +0.3% |
| 2025-09-29 | $560.75 | −0.6% |
| 2025-09-26 | $563.90 | +1.5% |
| 2025-09-25 | $555.51 | −3.7% |
| 2025-09-24 | $576.98 | +1.6% |
| 2025-09-23 | $567.89 | −4.7% |
| 2025-09-22 | $595.68 | +0.6% |
| 2025-09-19 | $591.99 | −1.1% |
| 2025-09-18 | $598.71 | +2.3% |
| 2025-09-17 | $585.50 | +1.8% |
| 2025-09-16 | $575.06 | +0.4% |
| 2025-09-15 | $572.59 | +2.2% |
| 2025-09-12 | $560.00 | −1.4% |
| 2025-09-11 | $568.20 | +2.2% |
| 2025-09-10 | $555.83 | −0.1% |
| 2025-09-09 | $556.53 | −0.3% |
| 2025-09-08 | $558.44 | −2.6% |
| 2025-09-05 | $573.38 | +1.1% |
| 2025-09-04 | $567.22 | +0.6% |
| 2025-09-03 | $563.80 | −2.4% |
| 2025-09-02 | $577.90 | −0.5% |
| 2025-08-29 | $580.70 | +0.2% |
| 2025-08-28 | $579.61 | −1.3% |
| 2025-08-27 | $586.96 | −0.1% |
| 2025-08-26 | $587.65 | +2.7% |
| 2025-08-25 | $572.38 | −2.9% |
| 2025-08-22 | $589.48 | −1.5% |
| 2025-08-21 | $598.16 | +1.2% |
| 2025-08-20 | $591.01 | +3.4% |
| 2025-08-19 | $571.78 | −0.4% |
| 2025-08-18 | $573.91 | −1.1% |
| 2025-08-15 | $580.41 | +2.6% |
| 2025-08-14 | $565.97 | +0.8% |
| 2025-08-13 | $561.55 | +0.9% |
| 2025-08-12 | $556.55 | +1.9% |
| 2025-08-11 | $545.94 | −3.0% |
| 2025-08-08 | $563.00 | +0.6% |
| 2025-08-07 | $559.80 | +0.8% |
| 2025-08-06 | $555.13 | −2.6% |
| 2025-08-05 | $569.90 | −0.3% |
| 2025-08-04 | $571.54 | +2.3% |
| 2025-08-01 | $558.87 | +2.5% |
| 2025-07-31 | $545.46 | −1.6% |
| 2025-07-30 | $554.58 | −0.6% |
| 2025-07-29 | $558.14 | −0.1% |
| 2025-07-28 | $558.63 | −0.8% |
| 2025-07-25 | $563.10 | −0.3% |
| 2025-07-24 | $564.64 | −1.4% |
| 2025-07-23 | $572.39 | +2.0% |
| 2025-07-22 | $560.93 | +2.8% |
| 2025-07-21 | $545.53 | +0.6% |
| 2025-07-18 | $542.52 | −1.4% |
| 2025-07-17 | $550.00 | +0.4% |
| 2025-07-16 | $547.93 | 0.0% |
| 2025-07-15 | $547.96 | −4.0% |
| 2025-07-14 | $570.59 | +0.5% |
| 2025-07-11 | $567.74 | +1.4% |
| 2025-07-10 | $559.76 | +1.3% |
| 2025-07-09 | $552.58 | +0.9% |
| 2025-07-08 | $547.75 | +1.8% |
| 2025-07-07 | $538.11 | −1.7% |
| 2025-07-03 | $547.36 | −0.1% |
| 2025-07-02 | $547.74 | +2.4% |
| 2025-07-01 | $534.91 | +1.9% |
| 2025-06-30 | $525.00 | +0.8% |
| 2025-06-27 | $521.00 | 0.0% |
| 2025-06-26 | $521.00 | +0.1% |
| 2025-06-25 | $520.29 | −0.4% |
| 2025-06-24 | $522.27 | +2.0% |
| 2025-06-23 | $511.92 | +0.4% |
| 2025-06-20 | $509.72 | −0.8% |
| 2025-06-18 | $513.58 | +0.9% |
| 2025-06-17 | $508.86 | −2.6% |
| 2025-06-16 | $522.68 | −1.2% |
| 2025-06-13 | $529.24 | +1.4% |
| 2025-06-12 | $521.84 | +0.6% |
| 2025-06-11 | $518.60 | −0.9% |
| 2025-06-10 | $523.53 | +1.1% |
| 2025-06-09 | $517.60 | +4.9% |
| 2025-06-06 | $493.22 | +2.1% |
| 2025-06-05 | $483.07 | −0.4% |
| 2025-06-04 | $484.93 | −0.6% |
| 2025-06-03 | $487.86 | −0.6% |
| 2025-06-02 | $490.81 | +0.1% |
| 2025-05-30 | $490.28 | −19.0% |
| 2025-05-29 | $605.39 | +2.3% |
| 2025-05-28 | $591.85 | −1.9% |
| 2025-05-27 | $603.26 | +2.5% |
| 2025-05-23 | $588.34 | −1.4% |
| 2025-05-22 | $596.85 | −1.3% |
| 2025-05-21 | $604.62 | −1.7% |
| 2025-05-20 | $614.79 | +3.1% |
| 2025-05-19 | $596.54 | +0.4% |
| 2025-05-16 | $594.32 | +1.6% |
| 2025-05-15 | $584.99 | +2.4% |
| 2025-05-14 | $571.36 | −0.5% |
| 2025-05-13 | $574.16 | −0.3% |
| 2025-05-12 | $575.63 | +9.1% |
| 2025-05-09 | $527.78 | −3.6% |
| 2025-05-08 | $547.67 | −2.4% |
| 2025-05-07 | $560.93 | +0.4% |
| 2025-05-06 | $558.52 | −7.5% |
| 2025-05-05 | $603.58 | −0.3% |
| 2025-05-02 | $605.61 | +2.6% |
| 2025-05-01 | $590.00 | −1.5% |
| 2025-04-30 | $598.76 | +5.2% |
| 2025-04-29 | $568.91 | −6.9% |
| 2025-04-28 | $610.86 | +1.4% |
| 2025-04-25 | $602.64 | +0.5% |
| 2025-04-24 | $599.76 | +2.0% |
| 2025-04-23 | $587.85 | +0.4% |
| 2025-04-22 | $585.49 | +4.3% |
| 2025-04-21 | $561.49 | −0.3% |
| 2025-04-17 | $563.16 | +2.5% |
| 2025-04-16 | $549.28 | −1.5% |
| 2025-04-15 | $557.91 | −2.3% |
| 2025-04-14 | $571.06 | +3.0% |
| 2025-04-11 | $554.18 | +1.4% |
| 2025-04-10 | $546.39 | −5.3% |
| 2025-04-09 | $576.72 | +3.6% |
| 2025-04-08 | $556.81 | −2.8% |
| 2025-04-07 | $572.78 | −0.1% |
| 2025-04-04 | $573.45 | −6.1% |
| 2025-04-03 | $610.64 | −2.4% |
| 2025-04-02 | $625.60 | +1.4% |
| 2025-04-01 | $617.00 | −2.7% |
| 2025-03-31 | $634.23 | −0.5% |
| 2025-03-28 | $637.36 | +0.2% |
| 2025-03-27 | $635.83 | −0.7% |
| 2025-03-26 | $640.14 | +0.9% |
| 2025-03-25 | $634.14 | −4.1% |
| 2025-03-24 | $661.00 | +0.4% |
| 2025-03-21 | $658.48 | −0.6% |
| 2025-03-20 | $662.62 | −1.4% |
| 2025-03-19 | $672.36 | +1.1% |
| 2025-03-18 | $664.96 | −2.0% |
| 2025-03-17 | $678.42 | +1.7% |
| 2025-03-14 | $666.87 | −2.0% |
| 2025-03-13 | $680.61 | −1.3% |
| 2025-03-12 | $689.50 | −4.0% |
| 2025-03-11 | $718.16 | −3.6% |
| 2025-03-10 | $744.83 | +5.3% |
| 2025-03-07 | $707.51 | +1.3% |
| 2025-03-06 | $698.44 | +1.6% |
| 2025-03-05 | $687.15 | +1.7% |
| 2025-03-04 | $675.49 | −1.4% |
| 2025-03-03 | $684.87 | −2.0% |
| 2025-02-28 | $698.74 | −0.6% |
| 2025-02-27 | $702.78 | −0.6% |
| 2025-02-26 | $706.94 | −2.3% |
| 2025-02-25 | $723.47 | +1.4% |
| 2025-02-24 | $713.25 | +1.8% |
| 2025-02-21 | $700.33 | +0.6% |
| 2025-02-20 | $696.02 | +1.5% |
| 2025-02-19 | $685.66 | +0.8% |
| 2025-02-18 | $680.00 | +1.0% |
| 2025-02-14 | $673.60 | −0.1% |
| 2025-02-13 | $674.27 | +1.6% |
| 2025-02-12 | $663.86 | −0.2% |
| 2025-02-11 | $665.46 | −3.6% |
| 2025-02-10 | $690.36 | −2.8% |
| 2025-02-07 | $710.00 | −1.7% |
| 2025-02-06 | $722.07 | +0.7% |
| 2025-02-05 | $716.72 | +2.8% |
| 2025-02-04 | $697.05 | +4.5% |
| 2025-02-03 | $666.85 | −0.9% |
| 2025-01-31 | $672.98 | −1.5% |
| 2025-01-30 | $683.08 | −0.6% |
| 2025-01-29 | $687.27 | +0.1% |
| 2025-01-28 | $686.33 | +0.2% |
| 2025-01-27 | $684.71 | +1.3% |
| 2025-01-24 | $675.79 | −2.7% |
| 2025-01-23 | $694.64 | +2.1% |
| 2025-01-22 | $680.03 | −1.1% |
| 2025-01-21 | $687.80 | +0.9% |
| 2025-01-17 | $681.58 | −1.7% |
| 2025-01-16 | $693.23 | −1.5% |
| 2025-01-15 | $703.43 | +1.8% |
| 2025-01-14 | $690.87 | −3.6% |
| 2025-01-13 | $716.90 | +2.9% |
| 2025-01-10 | $696.88 | −5.0% |
| 2025-01-08 | $733.59 | +0.5% |
| 2025-01-07 | $730.30 | +2.0% |
| 2025-01-06 | $716.26 | −0.3% |
| 2025-01-03 | $718.15 | +0.4% |
| 2025-01-02 | $715.19 | +0.4% |
| 2024-12-31 | $712.33 | +1.4% |
| 2024-12-30 | $702.59 | −1.4% |
| 2024-12-27 | $712.40 | −0.6% |
| 2024-12-26 | $716.68 | +0.3% |
| 2024-12-24 | $714.47 | −0.1% |
| 2024-12-23 | $715.13 | +1.9% |
| 2024-12-20 | $701.85 | −0.9% |
| 2024-12-19 | $708.25 | −0.9% |
| 2024-12-18 | $714.62 | −3.4% |
| 2024-12-17 | $740.01 | +2.1% |
| 2024-12-16 | $724.87 | −0.9% |
| 2024-12-13 | $731.30 | −1.3% |
| 2024-12-12 | $740.97 | −4.1% |
| 2024-12-11 | $773.00 | −0.7% |
| 2024-12-10 | $778.50 | −1.2% |
| 2024-12-09 | $788.00 | +1.3% |
| 2024-12-06 | $778.00 | +1.3% |
| 2024-12-05 | $767.90 | +1.8% |
| 2024-12-04 | $754.26 | +0.6% |
| 2024-12-03 | $749.57 | −1.7% |
| 2024-12-02 | $762.34 | +1.6% |
| 2024-11-29 | $750.22 | −0.6% |
| 2024-11-27 | $754.87 | +0.2% |
| 2024-11-26 | $753.03 | +0.5% |
| 2024-11-25 | $749.51 | +1.6% |
| 2024-11-22 | $738.00 | −0.9% |
| 2024-11-21 | $744.50 | +0.2% |
| 2024-11-20 | $743.35 | −0.2% |
| 2024-11-19 | $744.60 | −2.3% |
| 2024-11-18 | $762.00 | +0.7% |
| 2024-11-15 | $756.81 | −3.3% |
| 2024-11-14 | $782.51 | −2.7% |
| 2024-11-13 | $804.33 | −2.0% |
| 2024-11-12 | $821.00 | −0.6% |
| 2024-11-11 | $825.68 | −0.3% |
| 2024-11-08 | $828.42 | +0.5% |
| 2024-11-07 | $824.48 | +1.0% |
| 2024-11-06 | $816.65 | −1.5% |
| 2024-11-05 | $829.43 | +0.1% |
| 2024-11-04 | $828.84 | −1.7% |
| 2024-11-01 | $843.60 |
Oct. 6 is the last close in this chart. Source: Tiingo end-of-day closes, as traded, via KeyVex.
What the new deal says
The four antibodies were invented by Regeneron and are designed to be long-acting. They target IL-13, IL-4, the IL-4 receptor, and IL-4 and IL-13 at once.8-K Dupixent works on the same two signals: it inhibits the IL-4 and IL-13 pathways, the release says.Release Only the IL-13 antibody, REGN20423, is in human trials, an early-stage study in atopic dermatitis. The other three are expected to enter trials in 2027.Release
Profits from the new drugs, if any reach the market, are to be split 50:50 worldwide. Regeneron leads development, Sanofi leads sales.8-K On Dupixent, whose split stays as it was, the partners share U.S. profits equally. Outside the U.S., Regeneron's share runs on a sliding scale based on sales, from 35% to 45%, its 10-Q says.10-Q
The 8-K says development costs for all products in the collaboration, the four new ones included, will be shared equally. Costs above a budget cap for all four "will be the responsibility of Regeneron," the 8-K says, "subject to certain rights to recoup such excess costs in future years."8-K Under the collaboration so far, Sanofi initially funded a portion of development costs, and Regeneron repaid its share from its profits. The 8-K doesn't say Sanofi will fund any of the costs first.10-Q8-K
Regeneron also gets an option on lunsekimig, a Sanofi drug in late-stage trials for chronic obstructive pulmonary disease, once those trials end. If it exercises it, it would reimburse some of Sanofi's development costs.8-KRelease
How much rides on Dupixent
Source: Regeneron's 2025 10-K and its 10-Q for the quarter ended June 30, 2026.10-K10-Q
Regeneron's share of profits from Dupixent and Kevzara, the partners' other marketed drug, was $2.03 billion in the second quarter alone, about twice the upfront payment. A year earlier it was $1.28 billion.10-Q Sanofi recorded $6.2 billion of sales of the two drugs that quarter, up 38%.10-Q
Sanofi's $1 billion against one quarter of Regeneron's Dupixent and Kevzara profitsShow chartHide chart
View the data
| Amount | Billions of dollars | Note |
|---|---|---|
| Share of Dupixent and Kevzara profits (Second quarter of 2026) | $2.03B | $2,032.6 million, Regeneron's 10-Q |
| Share of Dupixent and Kevzara profits (Second quarter of 2025) | $1.28B | $1,282.1 million, Regeneron's 10-Q |
| Sanofi's upfront payment (Under the Oct. 1 deal) | $1.00B | $1.0 billion, Regeneron's 8-K |
The 10-Q reports Dupixent and Kevzara together. The filings don't assign any part of the $1 billion to the settlement. Sources: Regeneron's 10-Q for the quarter ended June 30, 2026; Regeneron's 8-K of Oct. 6, 2026.10-Q8-K
Regeneron had been repaying, out of its profit share, development costs Sanofi funded first under the collaboration: $253.0 million in the second quarter. That balance was fully repaid as of June 30, so from the third quarter it no longer reduces Regeneron's share, the 10-Q says.10-Q
How the deal was read
Regeneron closed down 3.1% at $734.81 on Oct. 1, from $758.27.Chart data StockStory said the sell-off reflected a market that saw the upfront cash as "insufficient compensation for diluting long-term margin upside." By agreeing to a 50:50 split on the new drugs without better Dupixent terms, it wrote, Regeneron gave up half of its next-generation pipeline's economics. It said nearly a quarter of investors surveyed by RBC Capital were seeking better Dupixent economics, citing Investing.com.StockStory
Jefferies wrote that "while the assets are early-stage," the expansion "should be viewed positively," Reuters reported.Reuters Regeneron's chief executive, Leonard Schleifer, called the alliance "one of the most productive in biopharma history."Release
The 8-K doesn't give the cap's size or the terms for recouping. Regeneron says it will file the full amendment with its 10-Q for the quarter that ended Sept. 30.8-K
What to watch
Regeneron files the full amendment to the Sanofi agreement as an exhibit.
The first quarter in which the repaid Sanofi development balance no longer reduces Regeneron's share of profits.
The three antibodies not yet in trials are expected to enter clinical studies.
Dupixent's U.S. composition-of-matter patent expires, per Regeneron's 10-K.
The paper trail
The records this story rests on, Nov. 18, 2024 through Oct. 6, 2026.
| Filed (ET) | Form | Filer | What it shows |
|---|---|---|---|
| Nov. 18, 2024 | Complaint | Regeneron | Sues Sanofi in federal court in New York over Dupixent information access and audit rights. |
| Feb. 4, 2026 | 10-K | Regeneron | Revenue from the Sanofi partnership was 41% of the 2025 total. Dupixent's U.S. composition patent runs to March 28, 2031. |
| July 30, 2026 | 10-Q | Regeneron | 48% of first-half revenue; the motion to dismiss denied March 17; the development balance repaid. |
| Oct. 1, 2026 | 6-K | Sanofi | The joint release: $1 billion up front, four antibodies, the litigation settled, Dupixent's split unchanged. |
| Oct. 2 and 5, 2026 | Docket | S.D.N.Y. | Stipulation of voluntary dismissal, then the order. |
| Oct. 6, 2026, 7:51 a.m. | 8-K | Regeneron | The terms: what the suit was about, the budget cap, the full agreement to come with the 10-Q. |
Sources
10 sources, 6 of them public records
Public records
- Regeneron Pharmaceuticals, Form 8-K (Sixth Amendment to the Antibody collaboration; settlement)SEC EDGAR · Oct. 6, 2026
- Regeneron Form 8-K filing index (acceptance time)SEC EDGAR · Oct. 6, 2026
- Regeneron Pharmaceuticals, Form 10-Q for the quarter ended June 30, 2026SEC EDGAR · July 30, 2026
- Regeneron Pharmaceuticals, Form 10-K for 2025SEC EDGAR · Feb. 4, 2026
- "Sanofi and Regeneron expand global Alliance with multiple next-generation, long-acting immunology antibodies" (Exhibit 99.1 to Sanofi's Form 6-K)SEC EDGAR · Oct. 1, 2026
- Regeneron Pharmaceuticals, Inc. v. Sanofi Biotechnology SAS, 7:24-cv-08751 (S.D.N.Y.), docketCourtListener (RECAP) · through Oct. 5, 2026
Reporting
- "Sanofi to pay Regeneron up to $8 billion to add new antibodies under Dupixent partnership"Reuters, via Investing.com · Oct. 1, 2026
- "Why Regeneron (REGN) Stock Is Trading Lower Today"StockStory, via Yahoo Finance · Oct. 1, 2026
Data
- End-of-day prices for REGN, and for SPY and QQQ on the chart (Tiingo)KeyVex · through Oct. 6, 2026
- The chart's Filings layer: KeyVex's Congress trade, insider trade, Form 144, 8-K and lobbying records for REGNKeyVex · through Oct. 6, 2026
How we got these numbers
- Prices are end-of-day closes as traded, not adjusted for dividends. Daily moves are close to close. Every Regeneron close in the chart's Story range is in its data table. The S&P 500 and Nasdaq 100 lines follow SPY and QQQ, also as traded, rebased to Regeneron's close at the start of the range shown. The Filings switch shows the filing markers from KeyVex's Regeneron stock page, a selection of congressional trades, insider trades, Form 144 notices, 8-Ks and lobbying filings: not every filing, and not only those tied to this story.
- The revenue shares are Regeneron's own: "Sanofi collaboration revenue (most of which is attributable to our share of profits from the commercialization of Dupixent)" as a percentage of total revenues, from its 2025 10-K (32% for 2024, 41% for 2025) and its 10-Q for the second quarter (48% for the six months ended June 30, 2026; $3,779.4 million of $7,896.1 million). Regeneron's share of Dupixent and Kevzara profits was $2,032.6 million in the second quarter of 2026 and $1,282.1 million a year earlier; Dupixent and Kevzara net product sales were $6,204.1 million and $4,496.8 million.
- Docket dates come from the court's docket as indexed by CourtListener's RECAP archive: entry 103, a stipulation of voluntary dismissal, filed Oct. 2, 2026, and entry 104, the stipulation and order, Oct. 5.