Is Regeneron Stock Increasing Your Market Risk

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If you hold Regeneron Pharmaceuticals (REGN) or plan to, its 19.0% rise from October 26 to November 2, 2026, while the S&P 500 fell 1.8%, likely caught your eye. Your other money probably already follows the market, so how Regeneron performs on the market's good and bad days matters for all of it. So does owning Regeneron make the rest of your money swing harder when the market moves?

Regeneron Stock Adds Little Market Risk, But Swings Widely

Mostly not. From the October 30, 2025 close to November 2, 2026, the S&P 500 rose 0.633% on its average up day, and a $10,000 holding in Regeneron gained about $46 on those days. When the index fell 0.606% on its average down day, that same holding lost only about $14. Over that year, Regeneron moved about 0.32% for each 1% move in the index. As a result, you get less of the market's daily moves from the stock than from an index fund, although it still gained about 73.1% as much as the index on up days.

But the stock is not a quiet one. Its volatility, measured by how widely its daily moves spread over a year, was 33.6% in that year, compared to 12.8% for the index. Those swings frequently ran against the market: in April 2026 the index rose 10.4% while Regeneron fell 8.5%. So Regeneron adds little to the market risk you already hold, but it brings a large risk of its own.

Will Regeneron Keep Moving On Its Own News?

Probably, because so much of Regeneron's results comes from a few drugs and a few regulatory decisions. Regeneron earns much of its money from Dupixent, the drug it shares with Sanofi. Management said on the October 30, 2026 call that Regeneron's collaboration revenue reached an all-time high of $2.7 billion in fiscal Q3 2026. EYLEA, its eye drug, is going the other way. Its revenue fell 42.4% in fiscal 2025, and management said the eye drug business faces increasing competition from additional biosimilar launches, which are cheaper copies of the drug. Management added that the business remains in a strong position despite that competition.

Management also expects an FDA decision in November on cemdisiran for generalized myasthenia gravis, and a lymphoma treatment is under FDA review with a February 2027 target action date. With that much riding on a handful of drugs and approvals, swings like the past year's are likely to continue. During that year, Regeneron's daily moves aligned only loosely with the index's, showing a correlation of 0.12 on a scale where 1 means the two move in step.

Has Regeneron Paid You For Those Swings?

Less than the market has. In the five years to November 2, 2026, Regeneron returned 8.3% a year, against 11.7% for the S&P 500. Its annual volatility over those five years was 31.6%, compared to 17.0% for the index. Dividing each yearly return by its volatility provides the return each unit of swing has earned: 0.263 for Regeneron, against 0.688 for the index, so its wider swings paid you less than the market's.

If the past year's pattern holds, Regeneron adds less to your money than the market on the next up day and takes less on the next down day, so it adds little to the market swings you already carry. Regeneron's own risk comes instead from Dupixent's profits, EYLEA's competition and the FDA's decisions. If you already own other drugmakers whose results depend on a few drugs and on regulators, Regeneron adds more of that same bet rather than spreading it.

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