Uncertainty at the top of WPP in the wake of Sir Martin Sorrell’s abrupt departure from the agency network he built over three decades has seen a surge in the number of investors betting against the advertising giant.

According to a report in The Times, the percentage of WPP shares on loan has risen from a negligible amount to close to 6% of its share capital in that time according to analysis by IHS Markit, with the number of WPP shares on loan rising just as the wider FTSE100 experiences a decline in such trades.

This process of ‘shorting’ or 'short selling’ sees investors borrow shares for a fee and selling them on with the intention of subsequently buying them back more cheaply at a later date and handing the shares back to their original owner.

It is estimated that there are now around 81m WPP shares on loan, equivalent to around £1bn based on its current share price with Marshall Wace and Old Mutual Global Investors amongst those actively shorting the ad giant.

WPP has seen its market value slashed by £5.6bn over the past year as it is buffeted by the perfect storm of Sorrell’s exit, a wider advertising downturn and increased competition from the likes of Google and Facebook.

Last week, Sorrell explained at an exclusive event in Cannes that the long-term succession plan was for the current chief operating officers Mark Read and Andrew Scott to take the reigns, a plan he still supports.

Sorrell heaped further pressure on his own creation last month when he announced plans to form a new global communications firm called S4 Capital, with heavy backing from institutional investors.