In a surprise move, Havas announced that Global CEO David Jones is leaving the company immediately, to become co-founder and CEO of a new tech business launching next month.

Yannick Bollore, who just became chairman of Havas at the end of August, said in a call with analysts and journalists that he will take on Jones’ role as global CEO of the Havas group. Andrew Benett is being promoted to Jones’ other post, as CEO of the Havas Worldwide advertising network. Benett has been global president of the network since January 2013.

“I’ve spent a lot of time around the tech and digital world,” said Jones, who in fact joined the call from the Consumer Electronics Show in Las Vegas. “I’m on Facebook’s client council. This bug has bitten me. My two big passions are social media and social responsibility. My new tech startup is at the intersection of those two things.”

Jones noted that he spent nine of his 15 years at Havas working with Bollore’s father, Vincent Bollore, who became Havas’ biggest shareholder with a 37 percent stake and its chairman before relinquishing that role to Yannick, who is just 33 and joined the Havas board of directors about three-and-a-half years ago, then added a VP role two years ago and a deputy CEO title in 2012.

Havas is the No. 6 agency company, with 2012 worldwide revenue of $2.28 billion, less than half the size of Dentsu Inc. at No. 5, according to Ad Age’s DataCenter.

Jones described his 15-year career at Havas as starting with running Australia and ending as the only British CEO of a French-listed company. He noted that Havas posted record financial results for the first half of 2013.

When Benett stepped up to global president a year ago, his contract specified that he would take on Jones’ global CEO role at the agency network in January 2014.