Michael Richards has left his role as group chief executive at Unlimited Group.
He departed Unlimited at the end of March. The company confirmed that it is searching for a replacement.
Unlimited Group, then called Creston, was acquired by investment firm DBAY in 2016 for £75.8m. Richards told Campaign that private equity ownership "wasn't for me" and he was seeking to move back to a more traditional agency environment.
Richards moved to Unlimited in April last year from VCCP, where he was international managing director. Before joining VCCP in 2016, he was involved in launching his own water brand, Vivid Water in a Box. Richards was previously chief executive of WFCA and held roles including board account director at Grey London.
Tim Bonnet, president of Unlimited, said: "Michael Richards joined the Unlimited Group 12 months ago to help drive new-business efforts across the group and has now made the decision to move on to a new challenge.
"A replacement will be announced shortly, as the group completes its third acquisition in 12 months, welcoming DirectionGroup Unlimited into the fold this month."
Unlimited announced the acquisition of business-to-business marketing agency DirectionGroup earlier this month.
Chris Pearce, chief executive of TMW Unlimited, is set to join rival agency MRM McCann later this year.