The pill is key to Novo's weight-loss franchise. The stock dropped 5.5% on Tuesday afternoon.

Novo Nordisk's new Wegovy pill had about $500 million in sales in the second quarter, although sales came in slightly lower than expected.

Novo Nordisk's Wegovy pill saw lower-than-expected sales that surprised investors, although it's been held up as the most successful drug launch of all time.

In an unexpected early release of its quarterly earnings, the Danish drugmaker said Tuesday that the Wegovy pill generated 32.2 billion Danish kroner (equivalent to about $500 million) in sales in the second quarter. That's slightly lower than the FactSet consensus of 33.2 billion Danish kroner.

The pill, which came to market in January, now competes against Eli Lilly's $(LLY)$ Foundayo, another GLP-1 pill that launched in the spring.

The Wegovy pill has been held up as a success story under Novo Nordisk's new leadership, recording more than 5 million prescriptions since January. However, even with a promising update to its full-year outlook, Novo's stock (DK:NOVO.B) (NVO) tumbled about 5.5% on Tuesday afternoon.

"Despite the underlying commercial strength, a surprise miss for the Wegovy pill ... coupled with lower-than-expected U.S. sales for injectable Wegovy likely contributed to the share move we are seeing today," BMO Capital Markets analyst Evan David Seigerman told investors on Tuesday.

Novo, which had been expected to release its second-quarter results on Wednesday, said it now anticipates adjusted sales growth for the year will be flat or as much as 6% lower, at constant exchange rates. That's a marked improvement over its estimate earlier this year that adjusted sales growth would drop 5% to 13% in 2026.

Novo attributed the improved outlook to "increased expectations" for its GLP-1s, which include the Wegovy pill and injection for weight loss and Ozempic for Type 2 diabetes.

In the second quarter, adjusted sales rose 7% to 78.49 billion Danish kroner (about $12.1 billion), against a FactSet estimate of 71.30 billion Danish kroner (about $11.0 billion). The obesity-drug business, which includes Wegovy, reported a 16% increase in sales on an adjusted basis.

Novo has struggled to regain its footing against Lilly, an aggressive and strategic competitor in the GLP-1 market.

That said, the company had some bright spots this year, including the successful launch of the Wegovy pill in the U.S., plus more recent launches in the U.K. and United Arab Emirates. But its pipeline has also taken a few hits, including the Phase 3 failure last week of ziltivekimab to reduce the risk of major cardiovascular events like heart attacks, and the decision announced Tuesday to scrap work on monlunabant, a Phase 2 asset that was being tested for obesity and diabetes.

Novo's U.S.-listed stock is down 14.4% so far this year, while the iShares U.S. Pharmaceuticals exchange-traded fund IHE has gained 19%.

-Jaimy Lee