Eli Lilly holds about 60% of the US branded obesity market

Eli Lilly held about 60% of the US branded obesity drug market through the summer of 2026, with Novo Nordisk's Wegovy franchise at roughly 40%, according to IQVIA prescription data cited by analysts at Citi and Jefferies. ^[1] Lilly's tirzepatide injection Zepbound remained the single most-prescribed obesity drug, while about a third of Wegovy's volume came from the semaglutide pill. ^[1]

The split held steady week after week. In mid-August, the obesity market share stood at 60.1% for Lilly and 39.9% for Novo, after Novo gave up about 0.7 percentage points in a single week. ^[1] By the Aug. 28 update, analysts described the "roughly 60%-40% obesity market share split between Lilly and Novo" as stable, with Zepbound holding its position as the most popular drug. ^[1]

The numbers behind the split

Wegovy's total weekly prescriptions, counting both the injection and the pill, moved in a narrow band: about 495,500 in mid-August, a little over 500,000 at the end of the month, and 513,500 in the week reported Sept. 4, a 2.7% sequential gain. ^[1] Zepbound scripts climbed 1.6% in that same early-September week to just under 772,000. ^[1]

The oral version of semaglutide made up 33% of all Wegovy obesity prescriptions in the week reported Aug. 14, then 35% in the weeks reported Aug. 21 and Aug. 28, and held at 35% into September. ^[1] Analysts noted the pill had "struggled to break through the one-third mark" for months. ^[1] Weekly Wegovy pill scripts ran from about 163,000 in mid-August to roughly 175,000 to 176,000 later in the month, then 181,000 and 183,000 in the two September reports. ^[1]

Lilly's oral GLP-1, Foundayo (orforglipron), grew from 34,219 weekly scripts in early August to 38,928, then dipped to 36,620, before crossing 40,000 for the first time in its 20th week on the market at 40,862. ^[1] By the Sept. 11 update it reached 47,500, up nearly 8%. ^[1] For comparison, Novo's Wegovy pill hit roughly 57,000 scripts in just its sixth week after launch. ^[1]

One important caveat: Citi analysts repeatedly warned that IQVIA may be missing some Foundayo prescriptions written through telehealth channels, so the pill's true volume could be higher than the tracked numbers. ^[1]

Broader market share figures, which include diabetes as well as obesity uses, tell a similar story. In late August, Lilly stood at 56.7% and Novo at 37.1%. ^[1] By Sept. 11, Lilly's tirzepatide held nearly 57% of the total GLP-1 market, up from around 49.5% a year earlier, while Novo's semaglutide was roughly flat at 37%. ^[1]

Why it matters for patients

Market share does not change how a drug works, but it does shape the environment patients deal with. When one company's products account for most prescriptions, that company has more leverage in negotiations with pharmacy benefit managers, which in turn affects which drug sits on a plan's preferred list and what a patient pays at the counter.

Access appears to be expanding overall. Citi found total GLP-1 prescriptions rose 5.4% over a four-week stretch ending in early September, compared with a 6.8% decline in the same period a year earlier. ^[1] Analysts attributed that 12-percentage-point swing to the arrival of oral GLP-1 options, which they said is "likely broadening access to the class and drawing in new patients." ^[1]

Coverage changes matter too. The Medicare GLP-1 Bridge program went live July 1, 2026, offering coverage of certain weight-loss drugs, including Foundayo, for a $50 monthly copayment. ^[1] Jefferies analysts observed that Wegovy has been "relatively flat since the Medicare GLP-1 Bridge program began July 1." ^[1] Lilly secured commercial access across the three largest pharmacy benefit managers in June, with CVS the last to add Foundayo coverage on June 1; Wegovy had full coverage in its first week on the market. ^[1]

Whether that translates into lower out-of-pocket costs for any individual depends on the specific plan, and the sources do not break down patient costs beyond the Medicare copay figure.

What happens next

Lilly reported $98 million in second-quarter Foundayo sales, including $67 million in the US, a figure that "disappointed" analysts who had modeled Wall Street consensus near $130 million. ^[1] Jefferies still expects the drug can reach the 2026 consensus estimate of $1.2 billion. ^[1] Lilly CEO David Ricks said broad direct-to-consumer marketing began after the June PBM wins, and Lilly USA president Ilya Yuffa said the company is "starting to see an inflection point on Foundayo now." ^[1] Whether that inflection narrows the 60-40 gap is not yet known.