Novo Nordisk Falls as Study Says Eli Lilly Weight-Loss Ingredient More Effective

The stock price of a pair of pharmaceutical companies are moving in opposite directions Tuesday following the publication of a new scientific study, with Eli Lilly (LLY) shares rising and American depositary receipts (ADRs) of Danish drugmaker Novo Nordisk (NVO) slipping.

On Monday, the JAMA Internal Medicine medical journal found that tirzepatide, the active ingredient in Eli Lilly's Mounajro and Zepbound, is more effective at causing weight loss than semaglutide, the active ingredient in Novo Nodrisk's Ozempic and Wegovy.

Study Finds Eli Lilly Drugs Caused More Weight Loss and at a Faster Pace

The study analyzed the weight-loss progression of over 18,300 patients who receiving semaglutide or tirzepatide for type 2 diabetes between May 2022 through November 2023.

Those taking Eli Lilly's tirzepatide were more likely to lose from 5% to 15% or greater body weight, and were also more likely to have lost more weight at 3, 6, and 12 months after starting treatment.

"Individuals with overweight or obesity treated with tirzepatide were significantly more likely to achieve clinically meaningful weight loss and larger reductions in body weight compared with those treated with semaglutide," the authors wrote, also noting that future studies should be conducted to track how effective the drugs are at preventing other health risks like heart attacks.

Eli Lilly, Novo Nordisk Sales, Share Prices Have Been Soaring

Thanks to the popularity of their weight-loss drugs, Eli Lilly and Novo Nordisk have seen revenue and profits rise substantially in the last several quarters, and have worked to increase production capacity to meet high demand.

In its most recent earnings report in May, Novo Nordisk said Ozempic and Wegovy sales rose 25% year-over-year, while Eli Lilly said sales of Mounjaro more than tripled to $1.81 billion and Zepbound sales had grown to $517.4 million after only launching in November 2023.

ADRs of Novo Nordisk were down 1.5% to $140.94 by about 1 p.m. ET Tuesday, while Eli Lilly shares were up 0.8% to $925.18. Novo Nordisk stock is up over 35% so far this year, while Eli Lilly is up nearly 60%.