An analysis by the UK’s Competition and Markets Authority has found that the Omnicom-IPG combination would have had the largest single share of media spend in the country last year had the merger been in effect with a combined share of between 30% and 40% of available ad supply. 

But the regulatory body concluded that there was enough competitive “constraint” in the marketplace—exerted mostly by competing holding companies—so that Omnicom’s acquisition of IPG would not constitute a “substantial lessening of competition.” 

As separate entities, Omnicom in actuality had a share of between 20% and 30%, roughly in line with the shares that both WPP and Publicis Groupe had for the 2024 period, according to the CMA rundown. IPG had a share of between 5% and 10%, while Dentsu had a share of between 10% and 20%. Havas’ share was estimated at up to 5% as was the collective share of independent agencies. 

The CMA issued its analysis Tuesday, about three weeks after the regulatory body announced that it had approved the merger without elaboration. (It noted at the time that its full report would be made public later.) 

“The evidence consistently indicates that WPP and Publicis exert a strong constraint on [a combined Omnicom-IPG entity],” the CMA concluded, based on an examination of holding company internal documents as well as interviews with agencies, media companies and advertisers across the UK market.  

“The CMA considers that WPP and, to a lesser extent Publicis, will have similar scale to the Merged Entity and will continue to compete closely, particularly with regard to the ability secure more favorable terms from media owners,” the CMA’s final report on probe stated. 

 “The evidence indicates that Havas and Dentsu exert a moderate constraint on the Parties, with Dentsu’s constraint being the stronger of the two.” 

Independents pose lesser constraints, particularly in terms of scale but do pose competitive strength particularly in areas where they have developed special expertise, per the CMA.   

The CMA’s full report can be accessed here.