Is Regeneron Stock Riskier Than It Looks?
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Regeneron Pharmaceuticals (REGN) stock returned 45.7% from November 3, 2025 to November 4, 2026, compared with 13.5% for the S&P 500. The business is growing too: revenue rose 36.3% from a year earlier in fiscal Q3 2026. Yet not every part of Regeneron is growing. One of its medicines has lost sales in each of the last two fiscal years, and management expects demand for it to fall again in the fourth quarter. What is that medicine up against?
Regeneron’s EYLEA Faces More Biosimilar Rivals
That medicine is EYLEA. Its rivals are biosimilars, which are copies of a biologic drug made by other drugmakers. On the October 30 call, management said the retinal franchise of EYLEA and EYLEA HD faces increasing competition from additional 2-milligram biosimilar launches, while still calling the franchise’s position strong.
Management also expects EYLEA demand to fall by a low- to mid-teens percentage in the fourth quarter from the third. EYLEA HD is not spared either. Although management expects its sales to grow more than 50% in 2026, it named ongoing pricing pressure on the product as an offset to that growth.
How Big Is Regeneron’s Eye Drug Business?
EYLEA and EYLEA HD together made up 31% of Regeneron’s revenue in fiscal 2025, the latest full year. The company reports each product as one of its own revenue lines.
The two lines moved in opposite directions that year. EYLEA’s sales fell by about $2 billion, to $2.75 billion, while EYLEA HD’s sales rose 36.3%, to $1.64 billion. This gain covered only part of EYLEA’s loss.
Regeneron shares trade close to the top of their past year despite EYLEA’s slide, closing on November 4 just 4.4% below their highest close of the past 365 days. On earnings, though, the stock is valued below the market, trading at 19.6 times the past twelve months’ profit against 22.8 for the S&P 500.
Should Regeneron Holders Worry About EYLEA’s Rivals?
Somewhat, because the threat is real. The eye franchise shrank in fiscal 2025, but its U.S. sales were close to flat in the latest quarter. In fiscal Q3 2026, combined U.S. sales of EYLEA and EYLEA HD were $1.1 billion, down 1% from a year earlier. EYLEA HD now makes up nearly two-thirds of those sales, and its U.S. sales rose 62% from a year earlier.
Regeneron’s latest growth came mainly from elsewhere. Management said fiscal Q3 2026 revenue growth came primarily from higher collaboration revenue from Sanofi, its partner on Dupixent. This collaboration revenue reached an all-time high of $2.7 billion.
Management is also counting on a prefilled syringe for EYLEA HD. The company is optimistic that the FDA will approve the syringe before the end of the year, and expects it to help sustain EYLEA HD’s growth in 2027 and beyond.
The number to watch is the combined U.S. sales figure for EYLEA and EYLEA HD, which Regeneron is expected to report in January 2027.
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