Nelson Peltz, the billionaire activist investor renowned for shaking up food giants Cadburys and Wendy's, is preparing what is thought to be his first significant investment in a high-profile company in the financial services industry – US asset manager Legg Mason.

Peltz is looking to build a stake of up to 20% in the asset manager, according to anonymous sources cited in the Daily Telegraph today, which could lead to the investor's representatives taking seats on Legg Mason's board.