Advertising agencies in the US have been systematically padding their profits by using non-transparent practices such as taking rebates from media companies and not disclosing them to clients, according to the Association of National Advertisers (ANA), which released the highly anticipated findings of an eight-month investigation into the sector on Tuesday.

The ANA – which represents the biggest global brands including Procter & Gamble, L’Oréal, Coca-Cola, Toyota, and Apple – said in its report that “numerous non transparent business practices” were “pervasive” in the media ad-buying ecosystem.

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