European markets closed Monday with little movement, as rising crude prices and a sharp decline in a major pharmaceutical firm counterbalanced each other. The benchmark Stoxx Europe 600 index finished essentially unchanged at the London close, digesting mixed sector performances throughout the trading session.

Energy shares took the lead as the top-performing sector, riding a wave of higher commodity prices following mutual strikes on oil tankers by the United States and Iran. On the opposite end of the spectrum, media and insurance stocks posted the most significant losses, weighing on the broader index's attempt to move higher.

A notable drag came from Novartis AG, whose shares suffered their steepest drop since April. The selloff was triggered by news that its potential blockbuster heart-disease drug, pelacarsen, failed to meet expectations in a late-stage clinical trial, a significant setback for the Swiss healthcare giant's pipeline.

Despite the overall flat performance, there were bright spots in the technology sector. Semiconductor supplier Soitec SA emerged as a standout performer, surging 12% and outpacing its peers amid a robust day for AI-related stocks across Europe. Additionally, Infineon Technologies AG advanced 6.9% following a rating upgrade from MP Capital Markets, adding to the positive sentiment in the chipmaking space.

Trading volumes were thinner than usual, with US markets closed for a public holiday, which may have contributed to the subdued overall movement in European indices.