Kelly Clark is to step down as global chief executive of Group M, the world’s biggest media buyer, and Christian Juhl, global chief executive of one of its flagship agencies, Essence, will take over.
It is thought that Clark, who is 53 and American, wants to step back for personal reasons after three years in charge.
Juhl, who is 46 and also an American, has a reputation as a digital-savvy leader who took over the leadership of Essence from its three British co-founders and sold it to WPP in 2015.
He will be in charge of 35,000 people and $48bn of billings at Group M, whose agencies include MediaCom, Mindshare and Wavemaker, as well as Essence.
Essence is best known as Google’s agency and it was apparent that Juhl’s star was on the rise when he was invited to speak at new WPP chief executive Mark Read’s investor day in London in December 2018.
Read said: "Christian has the right combination of leadership, people and technology skills to build the modern media company – something he has demonstrated extraordinarily well at Essence.
"We have a great number of talented people across Group M and its agencies, and I have every confidence in Christian’s ability to be an outstanding leader to them and an outstanding partner to our clients."
It is understood that WPP did not carry out a full search for Clark’s replacement, but was keen to make a "forward-looking" appointment of a leader who could hold the job for five to 10 years.
Juhl, who previously held roles at Publicis Groupe and Razorfish, and joined Essence in 2013, said: "I’m truly honoured and grateful for this opportunity to help deliver on Mark’s vision for WPP as a creative transformation company.
"Media frames the future for creativity, and Group M's incredible agency brands, talent, client partnerships and scale give us the unique opportunity to help reshape the industry and the way people think about advertising."
He took the helm soon after Group M suffered two heavy blows, when it lost Volkswagen Group and AT&T in 2016, and just months after the US Association of National Advertisers published a report into media buying transparency in that market.
Clark went on to merge two agencies, MEC and Maxus, to form Wavemaker, and Group M, like its parent WPP, suffered more client losses, including American Express and GlaxoSmithKline.
But Group M also showed signs of recovery under Clark’s leadership, winning Adidas and expanding its brief with Mars last year.
The WPP buying arm had further success this year, using Essence to retain the UK & Ireland account for L’Oréal, which was previously held by sister agency Wavemaker, and helping to win Centrica’s global integrated pitch.
Clark will continue as a senior advisor to WPP and Group M.
He said: "Today, we’re stronger and better-positioned to help our clients win in an intensely competitive business environment.
"I know Christian will work well with our leadership team to build further and faster on our ability to contribute to client growth. All of us in Group M have an inspiring new leader."
Read added: "Kelly has had a very successful three years as CEO of Group M, reflected in its recent strong run of new-business wins.
"I’d like to thank him for his dedication and leadership over many years with the company. I am delighted that he will support Christian during the transition and continue as a trusted senior advisor to the company."
Clark was chief executive of Group M North America from 2012 until 2015, when he stepped back for nearly a year, before returning to front-line duties as global chief executive in September 2016.
He started his WPP career at J Walter Thompson, which he joined in 1988.
Clark became UK chief executive of Mindshare between 2002 and 2005, and Europe chief executive from 2005 until 2008, when he then took the role of global chief executive at Maxus.