Was There Any Sign Regeneron Stock Would Run?

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An investor who bought a $10,000 stake in Regeneron Pharmaceuticals (REGN) at the October 31, 2025 close held about $15,010 on November 3, 2026. The company’s sales growth picked up over those twelve months. Management says most of the latest quarter’s gain came from the Sanofi partnership on Dupixent, with EYLEA HD and Libtayo adding to it. Was any of that visible before November 2025?

Regeneron Pointed To EYLEA HD In February 2025

Some of it was visible early on, and it showed first in Regeneron’s eye drugs. During its February 4, 2025 call for the fourth quarter of 2024, management talked about strengthening the profile of EYLEA HD by offering the treatment in a more convenient prefilled syringe.

Regeneron’s 2024 sales showed EYLEA HD already gaining ground on EYLEA. That year, EYLEA HD brought in $1.2 billion, against $4.77 billion for EYLEA. Because sales of EYLEA fell 16.7% in 2024 while EYLEA HD’s rose, a reader could see the eye business shifting toward EYLEA HD well before November 2025.

That shift did not come from the syringe. Management said on its October 28, 2025 call that the FDA had issued a complete response letter for the prefilled syringe the day before, and the device was still awaiting approval on the latest call. Early on, a reader could see the shift inside Regeneron’s eye business, not the syringe.

Regeneron Cited Dupixent’s Sales In October 2025

The larger part of the story appeared just three days before October 31, 2025. On that October 28, 2025 call for the third quarter of 2025, management said Dupixent’s global net sales reached $4.9 billion for the quarter. Sanofi reports those sales, while Regeneron books its share of the drug’s profits as collaboration revenue. Regeneron’s collaboration revenue as a whole had already grown 10.1% to $6.06 billion in 2024.

Regeneron’s own totals told a quieter story. Revenue for the quarter ended September 2025 grew just 0.9% from a year earlier, after a 3.7% fall in the quarter ended March 2025. The sign was a single line on a call while reported revenue barely moved, and you had to look past the totals to Dupixent to act on it.

What Had Changed At Regeneron By The Latest Quarter?

Regeneron stock beat the S&P 500, which returned 11.9% over the same dates, though Merck stock did better still at 73.2%. Amgen, another peer, also outran Regeneron at 58.8%. Even after the run, Regeneron trades at 20.5 times its trailing earnings, against 22.8 for the S&P 500.

The business change was Sanofi revenue. Sanofi collaboration revenue reached $2.7 billion in the third quarter of 2026, making up about half of Regeneron’s $5.1 billion in total revenue. Management said Regeneron’s share of those profits rose 77% from a year earlier, partly because the company finished repaying the Sanofi development balance in the second quarter and booked its full share of profits for the first time. That repayment is not one of the earlier signs this article found.

The drug behind that revenue is still growing. Dupixent’s global net sales reached $6.5 billion in the third quarter of 2026, against the $4.9 billion management gave for the same quarter a year earlier. That quarter, EYLEA HD’s U.S. sales rose 62% to $699 million, while U.S. sales of EYLEA HD and EYLEA together slipped 1% to $1.1 billion. The repayment, though, is already behind Regeneron, and management expects to book a $1 billion upfront payment from Sanofi as collaboration revenue in the fourth quarter. Dupixent’s global sales, as Sanofi reports them, are the figure to watch when Regeneron next reports, expected in January 2027.

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