WPP is poised to announce that MediaCom is moving into its Group M buying group with a revised UK and international structure.
In the UK, MediaCom's broadcast director, Mark Collins, is set to become the joint managing director of Group M alongside Nick Theakstone, the current managing director.
Sources said they expected MediaCom's UK entry into Group M to come in time for the autumn round of television negotiations and that other media channels may follow into Group M next year.
Collins had been linked with the head of media role at Carat, which was vacated by Mark Jarvis earlier this year, but he has opted to stay with WPP. Collins is expected to work with Theakstone to bring MediaCom's TV deals under the wing of Group M, joining those of MindShare and Mediaedge:cia.
The move is likely to create enlarged, international roles for Stephen Allan, MediaCom's UK chief executive, and Kelly Clark, MindShare's UK chief executive.
MediaCom, which is part of the Grey business acquired by WPP in March, is expected to separate from Grey's advertising business by the time Ed Meyer steps down from his role as the chief executive of Grey Global Group.
Sources suggest this will happen when his contract expires next year.
An early example of co-operation between MediaCom and MindShare took place last week when MindShare's Express Newspapers business moved into MediaCom to allow MindShare to pitch for the News International media account.
WPP created Group M in February last year, installing Theakstone, the investment director at MindShare, as the managing director. The group provides a centralised negotiation function while leaving the constituent agencies free to handle their own implementational buying across television and other media.
Group M launched with combined UK billings of more than £900 million - the addition of MediaCom's clients will bring this total closer to £2 billion. Omnicom followed WPP three months later by launching its own negotiation unit, OPera. Interpublic was the first holding company to pool its buying resources with Magna.
Collins and Theakstone were unavailable to comment as Campaign went to press.