Ad giant WPP faces brief stock slump after CEO resigns

Shares in British advertising giant WPP briefly slumped on Monday after chief executive and founder Martin Sorrell resigned over the weekend.

The stock dived more than 4.0 percent in opening deals after Sorrell stepped down on Saturday, but swiftly regained composure to stand almost flat at 1,187.50 pence.

The news nevertheless has sent shockwaves through the marketing industry, and comes 10 days after WPP launched an independent probe into allegations of his personal misconduct through the misuse of company assets.

WPP also revealed Saturday however that the probe had concluded, adding in a company statement that "the allegation did not involve amounts that are material".

Sorrell, 73, was easily the longest serving chief executive of a company on London's benchmark FTSE 100 index, having held the position since 1985.

He denied any wrongdoing after the allegations surfaced in early April.

"Obviously I am sad to leave WPP after 33 years," he added in the statement.

"It has been a passion, focus and source of energy for so long.

"However, I believe it is in the best interests of the business if I step down now. I leave the company in very good hands, as the board knows."

WPP chairman Roberto Quarta has been made executive chairman until the appointment of a new chief executive.