Group M's MediaCom is the world's leading media agency, according to RECMA, the agency evaluator, pushing Carat to second place.
Carat, which is the Dentsu Aegis Network agency, held on to the top spot in February 2014 and 2015, however dropped one place in May 2015 in Recma’s Network Diagnostics report.
MEC, the WPP-owned shop, took the third position in the top global agencies table. It means that OMD has moved from third place to fourth place, knocking ZenithOptimedia to fifth place.
Vizeum has jumped four places to ninth. Maxus, which was named the world's fastest growing media agency network over the past five years in last year’s RECMA report, has fallen from 10th place to 13th.
MediaCom said its leadership follows recent new business "success" including snapping up the Mars global planning and buying business.
In April, Tesco moved its £90 million ($140 million) media planning and buying account to MediaCom, ending its 20-year relationship with Initiative.
Stephen Allan, worldwide chairman and chief executive at MediaCom, said: "We’ve worked incredibly hard over the last few years to consistently build the global scale and expertise it takes to commit 100 per cent to all our clients while still winning new business."
Top 10 agencies globally (May 2015)
- Havas Media
- Starcom Media Vest Group
The next diagnostics report will be published in October.
This article first appeared on campaignlive.co.uk.