Ad Stacking

Ad stacking is a type of mobile display fraud in which an ad network or publisher stacks multiple ads in one ad placement unit. In these situations, only one ad impression is served but multiple advertisers are billed.

The best way to detect whether you are subject to ad stacking is to look at conversion from impression to click/install. Campaigns impacted by ad stacking or other sorts of display fraud tend to have high impressions and low click through rates or install rates.