North American CEO of the world's largest ad buying agency network, GroupM, has left after less than a year

Tony Barson/Getty Images for iHeartMedia

Tim Castree of Group M (right) with Brad Hiranaga of General Mills, Ryan Seacrest and Leslie Simms in 2019 in Cannes, France.

• Tim Castree, North American CEO of WPP's GroupM, has stepped down from the world's largest ad buying network, effective immediately, Business Insider learned.
• He assumed the role in late 2018, replacing Brian Lesser, who went on to lead AT&T's Xandr.
• GroupM and Castree issued nondescript statements and the company did not elaborate on its leadership plans for the immediate future.
• Sources with knowledge of the matter said the company's need to grow in its crucial region, North America, played a role in his departure.
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WPP's GroupM, the world's largest ad buying network, confirmed today that North American CEO Tim Castree has left the company, effective immediately.

His departure follows a large-scale restructuring effort and the July appointment to global CEO of Christian Juhl, to whom Castree reported.

"We thank Tim for his contributions and wish him the very best," said a GroupM spokesperson.

"I'm excited about the future for me. And bullish about the future for GroupM," Castree told Business Insider.

Several sources with direct knowledge of the matter said Castree's departure was announced to staff at GroupM this afternoon.

The change follows other leadership announcements and revenue struggles for WPP in its largest region

Juhl, who had formerly been CEO of Essence, a digital agency created to service Google, was promoted to lead GroupM globally in July upon the departure of his predecessor, Kelly Clark.

Castree joined WPP in 2017, overseeing the merger of media agencies MEC and Maxus to create Wavemaker, where he served as global CEO before being tasked with filling the role left empty when Brian Lesser left GroupM to lead AT&T's ad platform Xandr in the summer of 2017.

One source said Castree's exit came in response to GroupM and its parent company's well-publicized search for growth in the criticial North American region, where it suffered significant slips before reporting improvement during October's third-quarter earnings call.

GroupM declined to comment beyond the statement above.

The network's agencies include Essence, MediaCom, m/Six, Xaxis, Mindshare, Motion Content Group, and Performance Media Group. By its own estimates, the group handles more than $113 billion in annual media investments around the world for clients such as Ford, Google, and Facebook.

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