Here's How Much Eli Lilly's Weight-Loss Drugs Are Worth to Investors

Eli Lilly (NYSE: LLY) commands a market capitalization of about $1.06 trillion, and that valuation was built largely on two drugs: Mounjaro and Zepbound. Investors talk about the drugmaker's weight-loss and diabetes franchise constantly. But it's worth pinning down what these medicines actually contribute, and the company's most recent quarterly report gives a concrete answer.

In the first quarter of 2026, Mounjaro and Zepbound generated a combined $12.8 billion in revenue. That was almost two-thirds of Lilly's $19.8 billion in total revenue for the period -- a bigger share than I suspect many investors realize.

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A franchise still accelerating

Mounjaro, Lilly's tirzepatide-based treatment for type 2 diabetes, saw worldwide first-quarter revenue jump 125% year over year to $8.7 billion. Zepbound, the same molecule marketed for weight loss, grew revenue 80% to $4.2 billion.

And the pair's momentum isn't new. The two drugs combined for $6.2 billion of revenue in the first quarter of 2025, $11.7 billion in the fourth quarter, and $12.8 billion in the most recent period, meaning the franchise has more than doubled in a year and is still climbing quarter by quarter. For full-year 2025, the pair brought in $36.5 billion, more than half of Lilly's $65.2 billion in revenue.

Even more impressive, Mounjaro's growth rate is accelerating. It rose 99% for full-year 2025, 110% in the fourth quarter, and 125% in the most recent quarter. That is extraordinary acceleration for a product already generating billions of dollars every quarter.

Lilly's total first-quarter revenue rose 56% year over year, driven by a 65% increase in volume, partially offset by a 13% decline in realized prices. Growth was global, too, with U.S. revenue up 43% and revenue outside the U.S. up 81%.

And the surging franchise is showing up on the bottom line. Lilly's first-quarter earnings per share soared 170% year over year to $8.26, and non-GAAP (adjusted) earnings per share rose 156% to $8.55.

On the strength of the quarter, management raised its full-year revenue outlook to a range of $82 billion to $85 billion, a $2 billion increase from its prior forecast, and lifted its adjusted earnings-per-share guidance by $2 as well. The new revenue range implies growth of about 28% at the midpoint compared with 2025.

The pill, the pricing, and the price tag

In April, the franchise gained a third member. The FDA approved Foundayo, Lilly's once-daily orforglipron pill, for adults with obesity or overweight adults with weight-related medical problems. Lilly says it is the only GLP-1 (glucagon-like peptide-1) pill for weight loss that can be taken any time of day without food or water restrictions. And the company moved fast, opening prescriptions immediately and beginning shipments within a week of approval.

With self-pay pricing that starts at $149 per month for the lowest dose, the pill may open the market well beyond the population willing and able to take weekly injections.

Of course, the same concentration that makes the franchise valuable also makes it a risk. Nearly two-thirds of Lilly's revenue now rides on one molecule in one therapeutic area. And realized prices are falling, down 13% in the first quarter, including reductions in cash-pay prices for Zepbound.

Volume growth has overwhelmed the pricing pressure so far. If that ever flips, the market's enthusiasm could flip with it.

This brings us to the valuation. At about $1,184 per share as of this writing, Lilly trades at about 33 the midpoint of management's adjusted guidance range of $35.50 to $37.00 per share. That is a premium multiple, but it's attached to a company guiding for about 28% revenue growth -- and one that just raised that guidance by $2 billion.

So, how much are the weight-loss drugs worth to investors? They aren't a piece of the story -- they're most of it, accounting for nearly two-thirds of revenue and most of the company's growth. I think that premium is arguably earned at today's growth rates, and the new pill gives the franchise more runway.

Investors just need to know exactly what they own here. This is a trillion-dollar company whose results ride largely on one extraordinary family of medicines. That's a big opportunity, but also a big risk.

Daniel Sparks and his clients do not have positions in any of the stocks mentioned. The Motley Fool has positions in and recommends Eli Lilly. The Motley Fool has a disclosure policy.