LONDON (AP) — Martin Sorrell is stepping down as chief executive of WPP, the world's largest advertising agency, following allegations of personal misconduct.

Sorrell, who led WPP for 33 years, had been accused of misuse of company assets. He resigned Saturday night after the investigation concluded. The company announced the inquiry on April 3, saying "the allegations do not involve amounts that are material to WPP."

Sorrell, 73, says he opted to leave because "the current disruption is simply putting too much unnecessary pressure on the business, our over 200,000 people and their 500,000 or so dependents, and the clients we serve in 112 countries."

Sorrell took a UK manufacturer of wire baskets and built it into a worldwide provider of advertising, public relations and marketing services through a series of acquisitions.