European stocks trimmed their monthly gains on Friday as a significant slump in Novo Nordisk A/S shares weighed on the market. This decline countered a rally in tech stocks and a generally positive earnings season.

The Copenhagen-listed drugmaker, a significant component of the Stoxx Europe 600 index, fell as much as 8.3% after reporting that its anticipated weight-loss drug, Wegovy, faced a supply constraint impacting its launch in the U.S. This news sent ripples through the market, influencing investor sentiment.

Adding to the downward pressure, Universal Music Group NV also experienced a notable decline. Despite these setbacks, other sectors and companies reported largely upbeat results, indicating a mixed but generally resilient market performance. The overall monthly gain for European equities remained, albeit reduced by these prominent slumps.