Zenith Media is overhauling its entire structure for the first time since it was launched 11 years ago.
The UK's largest media agency, which until now has operated separate TV, press and planning departments, is pooling its groups under group account directors.
The three main media divisions will be split into four account groups, with managing partners Tom George, Rob Hill, Andy Smith and Rhona Tridgell each becoming account group directors.
George's accounts will include the entire Kingfisher business and Rover, while Hill will be responsible for Mars, Lloyds TSB and Toyota. Tridgell's key brands include BT, KFC and Campbell's, and Smith's portfolio will include Kraft Foods, the AA, Halifax and Carlsberg-Tetley.
A senior team of specialist directors will work under each group account director. Each division will include around 30 to 35 people.
Simon Marquis, the managing director of Zenith Media, said: 'The old departmental structure has been in existence since day one. We feel this is a more modern, client-focused way of operating. One of the benefits will be the new energy people will feel when they are asked to do things in different ways.'
The structure will be in place by 2 January. The four group account directors will report to Marquis, who is to take on more responsibility for the main running of Zenith UK.
Zenith is also seeking a new-business director, as Tim Greatrex, the deputy managing director who has been responsible for developing new business and marketing, will now oversee Zenith's direct operation, Zed Media, and Zenith Interactive.