San Francisco-based activist hedge fund ValueAct Capital Management LP disclosed a 5.4% stake in Merlin Entertainments Group, making it the third-largest shareholder in the U.K. theme park operator, according to a Feb. 19 London Stock Exchange filing.

ValueAct now holds 54.7 million shares in Merlin, which operates attractions under brands including Madame Tussauds, The Eye Brand, Sea Life and LEGOLAND parks.

Kirkbi Invest A/S remains Merlin's top investor holding 29.67% of the company's shares, followed by The Wellcome Trust Ltd, which owns 5.39%, or 55 million shares.

Meanwhile, ValueAct currently is the largest shareholder in Rolls-Royce Holdings plc, where it holds 10.73% of the engineering company's shares as of Jan. 31.