Wegovy outperforms tirzepatide on heart safety, Novo Nordisk stock rises

Novo Nordisk shares climbed over 2% following new real-world STEER study data, which showed its obesity drug Wegovy (semaglutide) 2.4 mg significantly reduced the risk of major cardiovascular events compared to Eli Lilly’s rival therapy tirzepatide. Presented at the European Society of Cardiology Congress 2025, the study indicated Wegovy was linked to a 57% greater reduction in heart attack, stroke, and death in compliant patients, reinforcing semaglutide's specific cardiovascular benefits and bolstering Novo Nordisk's competitive standing in the obesity treatment market.

Analysis

Novo Nordisk (NVO) shares gained over 2% following the release of new real-world data from the STEER study, which indicates a significant cardiovascular advantage for its obesity drug, Wegovy, over Eli Lilly's (LLY) rival therapy, tirzepatide. The study, presented at the European Society of Cardiology Congress 2025, found Wegovy was associated with a 57% greater reduction in the risk of heart attack, stroke, and all-cause mortality in compliant patients compared to tirzepatide. Even when including all treated patients regardless of adherence, Wegovy demonstrated a 29% superior risk reduction. These findings, based on an analysis of over 21,000 patients, strengthen the clinical evidence supporting semaglutide's specific cardiovascular benefits and provide Novo Nordisk with a potent competitive differentiator in the highly contested obesity treatment market. While the study's authors noted limitations, such as a short average follow-up period and the potential for unmeasured confounding factors, the results directly challenge Eli Lilly and are positively influencing investor sentiment towards Novo Nordisk's market position.

Key Decisions for Investors

• The STEER study data provides a significant positive catalyst for Novo Nordisk, potentially justifying a re-rating of its growth prospects as Wegovy's superior cardiovascular profile could drive market share gains from Eli Lilly.
• Investors in Eli Lilly should view this as a competitive headwind; it may be prudent to monitor for any forthcoming data or strategic response from LLY that could counter this narrative and defend tirzepatide's market position.
• While the results are favorable for NVO, the noted limitations of the real-world study, such as the short follow-up period, introduce a degree of uncertainty that merits caution before extrapolating these findings as definitive long-term outcomes.