Ad stacking is a deceptive advertising practice where multiple ads are placed on top of each other in the same ad spot, with only the top ad being visible to users. This fraudulent technique allows bad actors to charge advertisers for impressions on ads that users can't actually see. It's a serious form of ad fraud that wastes advertising budgets and distorts campaign metrics.
How ad stacking works
Publishers who engage in ad stacking will layer several ads in a single ad slot, creating an invisible stack where only the topmost ad is displayed. While users only see one advertisement, the tracking code registers impressions for all the stacked ads. This means advertisers are charged for ads that had zero chance of being viewed or clicked.
Why fraudsters use ad stacking
Ad stacking is attractive to dishonest publishers because it multiplies their revenue from a single ad placement. Instead of earning money from one legitimate ad impression, they can charge for 5, 10, or even more fake impressions simultaneously.
The practice is particularly harmful because it can be difficult to detect without specialized monitoring tools. Regular site visitors won't notice anything unusual since they only see the top ad.
Signs your ads might be getting stacked
There are several red flags that could indicate your ads are being stacked:
- Unusually high impression counts compared to site traffic
- Very low click-through rates
- Multiple impressions recorded at exactly the same timestamp
- Impressions coming from suspicious or low-quality websites
Protecting against ad stacking
Advertisers can protect themselves from ad stacking fraud through several methods. Using reputable ad networks with built-in fraud detection is essential. Implementing ad verification tools can help monitor ad placements and identify suspicious patterns.
Regular audits of campaign metrics and publisher performance can also help spot potential ad stacking. Look for unusual patterns in impression data and investigate any publishers showing signs of fraudulent activity.
