"They don't bring a lot of volume to the business in Asia, but they are huge in Europe," said Steedman.
In the UK, MediaCom clients are expected to bring Group M's combined billings to almost £2 billion (US$3.6 billion).
Steedman said WPP was looking to develop the MediaCom brand in Asia, while sharing back office costs and leveraging trading volume to drive efficiency. MediaCom's regional head Duane Bruner remains in place, based in Thailand. WPP will shortly announce a new Group M structure, with a regional general manager's role.