Eli Lilly Oral Weight-Loss Drug Foundayo Gains U.S. Market Share

Eli Lilly (LLY) announced on September 14, 2026, that its oral weight-loss medication, Foundayo, has captured more than 30% of new U.S. patients initiating treatment with an oral weight-loss drug. The company disclosed this milestone after launching the medication in the U.K. for weight management and type 2 diabetes later in August 2026. Lilly executives stated during an August 5, 2026 earnings call that the drug can be produced at scale, ensuring that supply constraints will not impede global launches. Management expects Foundayo to be on sale in all major markets worldwide in 2027, with more than 40 markets reviewing the treatment as of the August call.

Adoption metrics in the United States have accelerated significantly. The number of prescribers for Foundayo rose from 8,000 during the previous earnings call to 36,000 by the August 5 call. When asked about the pace of the U.S. rollout, which executives described as slower than anticipated, management noted that prescription volume in the last week of July was nearly double the level recorded a month earlier. This growth occurs within a rapidly expanding market where total U.S. prescriptions for incretin drugs for obesity increased by 78% in the second quarter of 2026.

Lilly’s existing portfolio continues to dominate revenue. In the second quarter of 2026, Mounjaro and Zepbound generated $14.9 billion of the company’s total $23.0 billion in revenue. Lilly holds approximately six in ten of all U.S. prescriptions for obesity incretin drugs and about seven in ten of those for injected medications. The company’s share is comparatively lower among non-injected treatments, the specific category where Foundayo competes. Patient access has also widened following the start of a Medicare program for obesity drugs on July 1, 2026, which management said resulted in 35% more people in the U.S. having coverage for Lilly’s obesity medicines.

The stock currently trades at a premium valuation of 39.5 times earnings, compared with 21.9 for the S&P 500. Shares have returned 39% over the past twelve months, outpacing the S&P 500’s return of 17.3%, and now sit 7.6% below their 52-week high. Beyond obesity, Lilly is pursuing expanded indications for Foundayo. Management expects a first trial result for obstructive sleep apnea before the end of 2026 and has applied in the U.S. to sell the drug for type 2 diabetes, a regulatory decision expected in 2026.