Changes are afoot at WPP's media buying unit Group M.

Sir Martin Sorrell's London-headquartered advertising holding company is reported to be moving its MediaCom business, acquired as part of WPP's takeover of Grey Global in March, into Group M in time for the fall round of TV negotiations.

Group M was created in February and provides a centralised negotiation function while leaving ad agencies free to handle their own implementational buying across television and other media.

The unit's UK billings at launch were around £900 million ($1.65bn; €1.33bn). The addition of MediaCom's clients will bring this total closer to £2 billion. Group M also has under its umbrella Mindshare and Mediaedge:cia

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 MD.

Data sourced from Brand Republic (UK); additional content by WARC staff