The chief executive of the world's largest advertising agency, WPP, is stepping down with immediate effect.
Sir Martin Sorrell has been at the helm of the company for 33 years since taking control in 1986.
The chairman of WPP, Roberto Quarta, will oversee the agency until a new CEO is appointed.
Sir Martin said his position at WPP had been a passion for so long but it was in "the best interests of the business" for him to resign.
He had been under investigation by WPP but had rejected any claim of financial impropriety.
In a statement, the firm said: "The previously announced investigation into an allegation of misconduct against Sir Martin has concluded. The allegation did not involve amounts that are material."
Who is Sir Martin Sorrell?
Formed WPP in 1985 after taking control of a shell company, Wire & Plastic Products, and established it as a marketing services group in 1986
Oversaw growth of company which now has 3,000 offices in 112 countries
One of UK's top-paid executives. His pay package in 2015-16 was £70m - then the biggest in UK corporate history - which more than a third of investors refused to back
A lack of succession planning for after the 73-year-old's retirement has caused some anxiety among investors
Roberto Quarta described Sir Martin as being the "driving force" behind WPP's growth and thanked him for his commitment to the business.
In a statement, Sir Martin said: "Obviously I am sad to leave WPP after 33 years.
"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."