REGENERON PHARMACEUTICALS, INC. (REGN) stock intrinsic value fair value estimate & owner earnings analysis

Regeneron is a Tarrytown, New York biotechnology company whose value rests on a discovery engine rather than one product. Its antibody and genetics platforms produced EYLEA and the longer-acting EYLEA HD for retinal disease, Dupixent for eczema, asthma and COPD (developed with and sold by Sanofi, with Regeneron taking a share of profits), Libtayo for skin and lung cancer, and smaller drugs Praluent, Evkeeza and Kevzara. In 2025 revenue was $14.3 billion: Sanofi collaboration income (mostly Dupixent profits) $5.9 billion, US EYLEA and EYLEA HD $4.4 billion, Bayer collaboration income $1.4 billion, Libtayo $1.5 billion. How we measure the cash. We start from operating cash flow, remove swings in working capital, subtract stock compensation (about $1 billion a year, a real cost paid in shares) and subtract the capital spending needed to keep the business as it is. On that basis owners earned $34.74 a share in 2022, $27.63 in 2023, $29.24 in 2024 and $23.60 in 2025. We set aside 2021 ($73.96) and the 2020 run-up, which were inflated by the one-off REGEN-COV antibody sold to the US government. Those figures include roughly $500-700 million a year of interest earned on the company's $18-19 billion investment portfolio. Because we count that portfolio separately as cash, we strip its income out, leaving the operating business producing about $2.7 billion in 2023 and 2024 and $1.95 billion in 2025. The 2023-2025 window is the right one: it is the business after COVID, during EYLEA's decline. Its median is about $2.7 billion. Cash flow fell about 29% in 2025 as US EYLEA sales fell 42% after biosimilars arrived following the end of exclusivity in May 2024. We start the base case's first year at $2.3 billion, above 2025, because the first half of 2026 already shows revenue up 18% ($7.9 billion vs $6.7 billion) and two quarters of cash generation running near $2.7 billion a year. We stay below that run rate because more EYLEA biosimilars are expected to launch in the US in the second half of 2026. What the company owns and owes. At 30 June 2026 Regeneron held $17.8 billion in cash and marketable securities. We hold back $2 billion as working cash. Debt is $2.0 billion of bonds: 1.75% notes due 2030 and 2.80% notes due 2050. These are fixed far below today's rates, so their true burden is about $0.5 billion less than face value. There is also a $720 million finance lease on the Tarrytown headquarters. Net, owners hold about $13.6 billion, or $128 a share, before the operating business is valued. Debt is no constraint on any case. A contingent obligation of about $595 million to reimburse Sanofi for past development costs is repaid only out of future Dupixent profits, so it is already inside the cash flows. The drivers that set the range. Dupixent's main US composition-of-matter patent expires 28 March 2031, and its profits are now the largest source of cash. EYLEA is already eroding, and EYLEA HD has to carry the franchise against biosimilars and rival drugs. Federal drug-price measures disclosed in the 10-K, including most-favored-nation pricing letters sent to Regeneron in July 2025 and proposed Medicare payment models, could weigh on US prices. Against these, the company has a demonstrated record: over roughly fifteen years its in-house science has produced EYLEA, Dupixent, Libtayo, Praluent, Evkeeza, Kevzara and others while spending heavily on research from its own cash. That record is the only reason any value is credited after the current products lose protection. Bear case: EYLEA and EYLEA HD keep losing ground as more biosimilars launch, US price measures bite, and operating cash falls from about $2.0 billion to $1.4 billion by 2030. When Dupixent loses its main patent in 2031, its profits erode the way EYLEA's did after 2024, a 40%-plus drop in the first year and continuing declines after. With no major new launch, cash settles near $0.5 billion a year, the level we think the smaller drugs and the research engine can sustain. The business is worth about $13.8 billion, owners keep $13.6 billion of net cash on top, and the total is $27.4 billion, or $258.90 a share. Base case: EYLEA HD and growth in Dupixent and Libtayo roughly offset EYLEA's decline. Operating cash rises from $2.3 billion to $2.6 billion by 2030, then Dupixent loses exclusivity in 2031 and cash falls back to about $1.5 billion. It holds there because the research engine has produced a meaningful new product about every two to three years. We give no credit to any specific pipeline drug that is not yet approved. The business is worth about $29.8 billion, owners keep the $13.6 billion net cash, and the total is $43.4 billion, or $409.87 a share. Bull case: Dupixent keeps the growth it has shown in COPD and newer indications through 2030, EYLEA HD holds its share, and Libtayo keeps growing as it has since Regeneron took full ownership. Cash reaches about $3.4 billion by 2030. Erosion after 2031 is softened by later formulation patents running to 2032 and by the engine's continued output, settling near $2.1 billion. The business is worth about $39.9 billion, plus $13.6 billion net cash, for $53.5 billion, or $504.82 a share. What changed since our previous analysis. The earlier figures are not comparable and should not be read as a change in the business. What is new in the business is the first half of 2026: revenue grew 18%, and the filings confirm more EYLEA biosimilar launches are expected in late 2026. How we set the margin-of-safety price. We are fairly sure of the earnings level for the next few years, because Dupixent's patent runs to 2031 and its profits are reported every quarter. We are much less sure what comes after 2031, and that is where most of the range sits. The worst plausible outcome is a faster collapse of the eye franchise combined with heavy US price cuts and an early Dupixent challenge. Even then, the structure of the company survives easily: almost no debt, $128 a share of net cash, and products that make money. The things we are most likely to be wrong about are how fast EYLEA HD erodes, how steep Dupixent's post-2031 decline is, and whether the research engine replaces it. If we are wrong against the company on all three, the shares look worth around the bear case of $259, about half of it cash. While waiting, the business pays a $0.94 quarterly dividend and buys back shares, which have cut the diluted count from 115 million to 106 million in two years. The price assumes a two-to-three-year holding period for the price to reflect a value around the base case. At $255 a share, the price is roughly the bear case. Half that price is covered by cash, and the operating business, which has produced $2-3 billion a year, is valued at about $13 billion. On those terms the base case implies a 20% annual return from only a modest move toward the base case over that period plus the dividend, and the downside is confined to outcomes worse than our bear case. That is why the margin-of-safety price is $255.