Novo Nordisk's shares have declined by 25% in March, marking their largest monthly drop since July 2002. Concerns among investors are growing that the Danish pharmaceutical company has fallen behind its American rival Eli Lilly in the obesity drug market. Despite Novo's weight-loss injection Wegovy launching successfully and briefly making it Europe's most valuable company by market capitalization in September 2023, it has now been overtaken by German software company SAP and faced competition from Lilly's Zepbound, which showed better weight loss results in clinical trials.

Investors and analysts have noticed a shift in sentiment towards Novo, with its market value halving since last summer and share prices dropping by 23% this year. In contrast, Lilly's shares have seen a 6% increase. The prevailing view is that Wegovy is inferior to Zepbound, and there are doubts about Novo's future performance through 2025.

Despite efforts to increase the supply of Wegovy in the U.S. market, weekly prescription data show stagnant numbers for Novo's drug compared to the higher prescriptions for Lilly's Zepbound. Novo's launch of the obesity drug CagriSema in late 2024 and early 2025 also failed to meet expectations.

Barclays analyst Emily Field highlighted the additional pressure on Novo due to potential U.S. tariffs affecting the pharmaceutical industry. Field noted that Novo's production of the active ingredients for drugs like Wegovy and Ozempic in Denmark could face challenges.