Ad Stacking 101 – The What, Why, and How

Mobile Ad Fraud continues to be daunting challenge for Advertisers and Marketers. Just how big of a problem is ad fraud? In 2019 alone, North America and China saw losses to the tune of $2.6 billion and 18.7 billion, respectively. While ad fraud losses are placed at $35 billion for 2020, it is forecasted to cost the industry over $50 billion by 2025. With fraudster resorting to increasingly sophisticated techniques of ad fraud, and the resulting losses set to witness a damaging increase, curbing ad fraud remains a priority.

What is Ad Stacking?

Ad Stacking: There is more than what meets the eye

In its literal sense, Ad Stacking is a form of mobile ad fraud where ads are stacked one on top of the other in the same ad placement. Prevalent in cost-per-million (CPM) and cost-per-click (CPC) campaigns, only the top layer of the ad stack is visible to the user. Unbeknownst to the user, much like an iceberg, hidden below the visible ad are sometime multiple layers of ads. When the user clicks on the ad, that single click is fraudulently registered across all the ads present in the ad layers. In doing so, Advertisers are charged and pay for false ad impressions and clicks.

Why is it important to detect Ad Stacking?

While on the surface Ad Stacking may seem like a relatively juvenile form of Ad Fraud, its effects are far reaching. Advertisers and Marketers continue to fall victim to Ad Stacking as it impacts pivotal campaign activity, namely:

  • Siphoned Campaign Budget: The nature and function of Ad Stacking is to drive wrongful revenue for the fraudulent parties involved. With each phony impression and click registered, Advertisers are charged. This leads to a depletion of campaign budgets and a poor return on ad spend (ROAS).
  • Skewed Data: In an industry such as ours, data is key. The registration of fraudulent impressions and clicks across multiple ad layers results in compromised data which has a cascading effect. The dependence and use of this erroneous data and subsequent optimization that follow would not translate to expected outcomes.

How do you identify Ad Stacking?

The most telling sign of Ad Stacking activity being prevalent in any of your campaigns is a high impression tally with a low click through rate (CTR). This is due to the flood of fraudulent impressions resulting from multiple layers of ads in contrast to the low genuine interest and clicks from authentic sources.

In the event of multiple campaigns, a more detailed check on the back end to check the timestamp of ad clicks against the device ID will help identify Ad Stacking activity. When an ad in an Ad Stacking activity is shown to a user, the genuine click is registered at the same instant, using the same device ID, across all ad layers in the ad placement. Hence, identifying correlations in the timestamp vs device ID will help Marketers detect Ad Stacking activity. However, it is to be noted, this identification only occurs post the fraudulent activity. Due diligence must be taken to investigate and block the source of this fraudulent activity to curb its growth and effect.

To know more about Ad Stacking or to learn how Kaden can help you keep a lid on Ad Fraud, drop us a note at

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