Tim Castree has been appointed North American CEO of WPP’s media investment arm GroupM.

Moving from his position as global CEO of GroupM media agency network Wavemaker, Castree will be responsible for improving strategy and operations across the U.S. and Canada. He will be based in New York.

GroupM’s agencies include Mindshare, MediaCom, Wavemaker, Essence, m/Six and Xaxis.

Castree stepped into his role as Wavemaker’s global CEO in 2017 as global agencies Maxus and MEC (where Castree served as global CEO) merged. Wavemaker is now the second-largest media agency in the world, according to GroupM.

During his time as global CEO, Castree led a group-wide team, “creating a strong vision and structure for Wavemaker,” according to a statement by GroupM’s global CEO Kelly Clark. Castree will report to Clark in the new role.

“[Castree’s] focus on client growth led to the creation of a new global agency and inspired group-wide collaboration in a number of important areas,” the statement continues.

According to a release from the WPP media investment group, Castree will continue his work with the leadership team at Wavemaker while the media company searches for his replacement.

Castree’s industry experience includes more than two decades at global creative, media and digital agencies which include his role as CEO at Leo Burnett Australia, COO at Publicis Group’s MediaVest U.S., Managing director and head of North America at Videology and global managing director for Starcom MediaVest.