Stocks for Omnicom, IPG and WPP all closed slightly higher at market close Tuesday, underlining how difficult it is to really quantify the impact of the Association of National Advertisers report that found that non-transparent practices existed in many corners of the media agency landscape.

IPG closed about 1 percent higher at $23.96; Omnicom also about 1 percent at $83.27, and WPP closed at $116.27, 1.7 percent higher. No investment banks changed their ratings on big holding company stocks.

Read the full Digiday article here.