Coup for embattled Sir Martin Sorrell as WPP swoops for a majority stake in AKQA

The British founders of AKQA, the world's biggest independent digital advertising agency, are celebrating after Sir Martin Sorrell's WPP bought a majority stake which values the business at around $540m (£343m).

Ajaz Ahmed and James Hilton, who co-founded the agency in 1995, will remain with AKQA, which creates online ads, smartphone apps and games for clients such as Nike, Heineken, Microsoft, Google and Virgin Money.

Mr Ahmed, the chief executive, said it made sense to sell because the agency wanted greater global scale and there was "a shared understanding of values and ambition" with WPP, the world's biggest ad group.

News of the deal, one of the biggest in advertising in recent years, caused a buzz of excitement at Cannes where agency bosses, including Sir Martin, are meeting for the week-long Lions festival, the most important global industry event of the year.

Mr Ahmed launched AKQA at the age of 21 and named it after his initials. He said money was not a motivation for selling as AKQA and its private-equity backer, General Atlantic, had turned down multiple approaches previously.

The AKQA chief executive added that he remains committed to the business and, after agreeing the deal with WPP, he travelled to America, rather than to the Cannes Lions.

"While everyone else is sunning themselves in Cannes, I went to Los Angeles for one client meeting for one day," he told The Independent.

AKQA chairman Tom Bedecarré will also stay on and becomes president of WPP Ventures, a new Silicon Valley-based investment subsidiary.

AKQA, which is jointly headquartered in Britain and America, employs around 330 people in glossy offices in Farringdon, east London, and 1,160 worldwide in nine cities, but Mr Ahmed said being part of WPP would instantly give it access to dozens of countries.

The AKQA acquisition is a coup for Sir Martin, who faced a revolt by 60 per cent of WPP shareholders over his £13m pay package last week.

Sir Martin said "AKQA's unique team of technological innovators and entrepreneurs" would boost WPP, as brands increasingly look to communicate with consumers through the web and mobile phones.

WPP and several rival groups had tried unsuccessfully to buy AKQA in recent years.