How Much Upside Is Left In Regeneron Stock?
Regeneron Pharmaceuticals (REGN) stock returned 37.9% in the year to October 16, 2026. This easily outpaced the 16.2% gain for the S&P 500 and left investors looking at a higher price. The underlying business has grown faster lately, yet its operating margin has slipped in each of the past three years. If you buy or hold the shares today, what could three more years of owning them make you?
Regeneron Stock Would Gain About 29% In Three Years
A Trefis scenario built directly from the company’s own figures projects that Regeneron stock would gain about 29.3% over three years. Excluding dividends, this equals an 8.9% annual return. The model assumes revenue will grow at 85% of its latest yearly pace. It calculates the operating margin using a blend of today’s margin and the three-year average, with a heavier weight on current levels, and it leaves the P/E unchanged.
The shares currently trade at 18.8 times earnings. Over the latest twelve months, Regeneron recorded a net profit that was higher than its operating profit, so the scenario models its projections from the operating margin. The current P/E sits slightly below the stock’s historical average of 19.3 recorded at quarter ends over the past three years.
Here is Regeneron today beside the scenario three years out.
| Today | In three years (scenario) | |
|---|---|---|
| Revenue | $15.5 billion | $19.5 billion |
| Operating margin | 26.9% | 27.6% |
| Earnings | $4.33 billion | $5.60 billion |
| P/E | 18.8 | 18.8 |
| Share price | $790.74 | $1,022.12 |
The flat P/E assumption means the entire stock gain relies on business performance, with 88.8% of the projected upside tied directly to higher revenue. Regeneron’s largest revenue line is collaboration revenue, which includes its share of the partnership with Sanofi. This segment rose 21.0% to $7.33 billion in fiscal 2025. During that same year, EYLEA HD sales rose 36.3% to $1.64 billion.
When Regeneron Pharmaceuticals is a large share of what you own, your plan depends on the business delivering more. See how to protect a concentrated position.
What Regeneron Needs From Dupixent And EYLEA HD
To succeed, Regeneron must keep its newer drugs growing faster than the older EYLEA shrinks. The company forecast its fiscal 2026 costs and margins in a July 30 release, but it left out revenue guidance. As a result, management’s account of sales comes from the call. Dupixent, the drug Regeneron develops with Sanofi, generated $6 billion worldwide in fiscal Q2 2026. Sanofi reported that this figure was up 38% from a year earlier at constant currency. On the July 30 call, management noted that both companies see plenty of room for Dupixent to grow, including in more age groups and countries. Management also expects Sanofi collaboration revenue to step up starting in fiscal Q3 2026, when Regeneron begins recording its full share of the profits.
The newer EYLEA HD posted U.S. sales of nearly $600 million in fiscal Q2 2026, rising 52% from a year earlier. Over the same quarter, U.S. sales of the older EYLEA fell 45% to $412 million. Combined, the two drugs sold less in the U.S. than they did a year earlier. Management expects demand for the older EYLEA to keep falling through the second half of 2026 as more biosimilar copies launch.
How Regeneron’s Upside Changes Under Other Assumptions
Here is the upside with one assumption changed at a time.
| If instead | Upside |
|---|---|
| Nothing changes (the scenario) | 29.3% |
| Revenue growth of 5.9% a year instead of 7.9% | 22.2% |
| Operating margin of 29.5% in year three instead of 27.6% | 37.8% |
| 5 years at the same assumptions instead of 3 | 50.5% |
This baseline scenario starts from a period of accelerated growth. Regeneron recorded faster revenue growth in the twelve months to June 2026 than in either of the prior two years. At the same time, its operating margin sat below the average recorded at the quarter ends of the past three years.
If the rest of the scenario remains unchanged, revenue could shrink by about 0.95% a year before three years of owning the stock return nothing. This compares to 9.3% growth in the latest twelve months. The operating margin could fall to 21.4% from 26.9% today. Finally, the P/E could drop to 14.5, a level the stock traded below at the ends of June and September 2025.
Regeneron’s overall revenue growth is the measure to watch in the fiscal Q3 2026 report, expected on or around October 30, 2026. This top-line figure includes both its Sanofi collaboration revenue and sales of the newer EYLEA HD.
Is Too Much Of Your Wealth Riding On One Stock?
Any gain in Regeneron Pharmaceuticals from here depends on the business delivering more. When one position grows into a large part of your wealth, a sharp fall can hurt your whole plan, and selling to spread the money out can bring a large tax bill. Glenn Caldicott, CIO of our Boston-based partner firm Empirical Asset Management, an SEC-registered investment adviser, offers a free 15-minute strategy review of ways to protect a concentrated position and unwind it with less tax.