The threat of a triple-dip recession in the eurozone, civil unrest in China and the Ebola crisis have created an unprecedented number of headwinds for the global economy, according to the chief executive of WPP. Sir Martin Sorrell, founder of the world's largest advertising group by sales, said geopolitical risks "continued to multiply" and had hit confidence among major advertisers. WPP posted a lower-than-expected increase in like-for-like sales in the third quarter and said it expected sales to slow further in the coming three months.