ZURICH (Reuters) - Activist investors are expected to step up their campaigns across Europe this year, with American firms increasingly involved buying into companies to put pressure on their management, a study said on Wednesday.

Low market valuations of European companies make it cheaper for U.S. firms to build stakes and demand changes, according to the report by professional services company Alvarez & Marsal.

Last year, 35% of public activist campaigns in Europe were launched by U.S. based funds, up from 27% in 2023, with Britain, Switzerland and Germany, increasingly in their sights.

One of Wall Street's most activist investors, Jeffrey Ubben, was made a non-executive director at Bayer last year, having long urged the German chemicals company to be broken up.

"U.S. activists are continuing to make their presence felt in Europe, and this growing appetite shows no sign of subsiding," said Malcolm McKenzie, Chair of European Corporate Transformation Services at A&M.

"The UK, Switzerland and Benelux are already established hunting grounds while Germany is also expected to become a growing target."

U.S. activists see a chance to improve performances after European stocks gained an average of 8% last year, lagging the 29% average increase at U.S. companies.

The U.S. influx has been particularly marked in Switzerland, where 53% of campaigns since 2020 have been by American-based activists, the study said.

Overall, A&M said 141 companies could be at risk of public shareholder activism in Europe over the next 18 months. It declined to identify them.

Britain has the most potential targets, with 49 companies, it said, followed by Germany with 33, then Switzerland.

"With 17 likely targets, Switzerland is expected to see the largest increase in shareholder activism," said A&M.