The news: Novo Nordisk’s stock plunged over 20% on Tuesday after it cut full-year guidance, citing lower-than-expected sales growth for Wegovy, its blockbuster weight loss drug.

• Novo now expects 2025 sales growth of 8% to 14%, down from prior projections of 13% to 21%.
• It forecast operating profit growth of 10% to 16%, down from its earlier view of 16% to 24%.

Driving the news: It’s been a tumultuous 2025 for Novo, which is also undergoing a leadership transition with a new CEO starting next month. Shares are down nearly 60% in the past year.

Novo attributed much of the slowdown to continued competition from compounded versions of semaglutide (Wegovy), which is cutting into sales of the drugmaker’s brand-name version. It specifically called out some providers that market compounded GLP-1s “under the false guise of personalization.”

For context: Some companies like Hims & Hers are still legally permitted to prescribe personalized GLP-1s to patients meeting specific health requirements. Novo and Hims recently terminated a distribution partnership over Hims’ refusal to stop selling these compounded formulations.

Yes, and: Novo put itself at a disadvantage relative to GLP-1 rival Eli Lilly by failing to anticipate supply issues, which opened the door for online players to sell compounded semaglutide at a discount. Wegovy prescriptions have also declined in favor of Lilly’s Zepbound, which is the more effective weight loss drug of the two.