Air Liquide shares rose around 3.8% after reports that activist investor Elliott Investment Management had built a stake in the Paris-based industrial-gases company and was pressing management to improve margins and compete more effectively with Linde and Air Products and Chemicals. People familiar with the matter said Elliott has engaged with Air Liquide for months, although the size of its holding could not be learned. Analysts say the margin gap between Air Liquide and Linde has widened to 9 percentage points and may remain at that level for some time, reflecting the success of Linde's operational optimization plan. The move came as European stocks traded broadly flat to higher at the start of September, with rising oil prices supporting energy shares while adding to inflation concerns and expectations for further European Central Bank tightening.