The tycoon, who built WPP into the world's largest advertising agency, strenuously denies claims of misconduct and of misusing company funds. While the timing was sudden (and perhaps calculated to limit immediate PR damage), his exit is not all that surprising.
Sir Martin had been the subject of an internal investigation into an allegation of financial misconduct, but his resignation still came as a surprise. It said the allegation "did not involve amounts that are material". Below, a look at how his exit was greeted on social media. "However, I believe it is in the best interests of the business if I step down now".
Roberto Quarta said: "Sir Martin has been the driving force behind the expansion of WPP to create the global leader in marketing services".
WPP is Sorrell's creation, built up over 33 years, but with his departure and a radically changed advertising landscape, there is an expectation that just as the constituent parts had been assembled so they will now likely be dismantled.
Sir Martin was said to have resigned after learning that the investigation had finished, though sources...
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Analysts have speculated that the sprawling group, which was being restructured after a year of lower spending from some clients, could now sell off some assets if led by different management. So if WPP does well, I do well, and others in the company do well.
Sorrell, who is among the highest paid British executives, earned over $100 million in 2015 and 2016.
The acquisitions included the J Walter Thompson Group, the Young & Rubicam Group and the Ogilvy Group.
Present in 112 countries, WPP serves clients including Ford, Unilever, P&G and a string of major corporations around the world.
He previously worked at Saatchi and Saatchi, and was knighted in the Queen's New Year honours list in 2000. But it has been hit in the last 18 months by a downturn in spending from consumer goods groups Unilever and P&G, and the loss of some big accounts. Its shares are down around 30 percent this year. During this time, the Company has been successful because it has valued and nurtured outstanding talent at every level - within and well beyond our leadership teams. "Now back to the future".