April 4 (Reuters) - WPP, the world's biggest advertising company, is investigating an allegation of personal misconduct against Chief Executive Martin Sorrell who has denied wrongdoing.
Sorrell, who built WPP into the industry leader over three decades, said the allegation concerned financial impropriety and specifically the use of company funds.
"I reject the allegation unreservedly but recognise that the company has to investigate it," he said on Wednesday.
WPP said the allegation did not involve amounts which were material to the company.
Shares in the British company, already down 36 percent in the last 12 months, fell to more than four-year lows on Wednesday. They were down 2.1 percent at 1,094 pence at 0803 GMT.
Sorrell said the allegation was being investigated by a law firm, and he understood the process would be completed shortly.
"Obviously, I shall play no part in the management of the investigation under way," said Sorrell, one of Britain's best-known business leaders.
The investigation was first reported by The Wall Street Journal.
Sorrell built WPP from a two-man operation in a London office in 1985 to one that now dominates the industry with around 134,000 staff in more than 100 countries. (Reporting by Shalini Nagarajan in Bengaluru and Paul Sandle in London; editing by Peter Cooney and Jason Neely)