Deering's decision to leave will come as a blow to the agency - he has spent the past 12 months plugging the gaps left when the creative directors, Sam Ball and Dave Bedwood, along with Tom Bazeley and Dave Cox, left to set up the creative hotshop Lean Mean Fighting Machine in February last year.
His decision to leave now, when the agency has all but bounced back, will come as a surprise to many in the industry. Tribal has picked up some good pieces of business of late, including Domestos, Camelot and Marmite.
"I've been considering a change for a while and now is the time to leave, precisely because things are going well," Deering said. "Tribal is in good financial shape and there is a strong management team in place which has been working with me on running the business."
The DDB chairman and chief executive, Paul Hammersley, has briefed headhunters to conduct a search, both internally and externally, for a replacement.
There is currently no official date for Deering's departure, but he is expected to leave in two months' time.
Deering has been at Tribal for six years and started as a media planner.
He was promoted from head of media to deputy managing director in 2002 and became the managing director in 2003, following Alison Parker's departure.