I think the analogy here with Wall St is apples and oranges. In Wall st, the security traded is fungible. Here in the ad world, an ad view could be high quality or lower quality. It could be a bot or a human looking to buy something.<p>I am an engineer who spent 12 years in the ad tech industry. This problem is especially acute in the online video ad side where dollars are exchanged based on views and CPMs, not someone buying something online (this being more accountable is less open to abuse). In my old job, we tested what % of traffic are fraudulent. These traffic are daisy-chained from one ad buyer/seller to the next. Inevitably it will hit someone unscrupulous. In aggregate we found anywhere from 20% to 95% of the traffic we see for video ads to be fraudulent.<p>There are some very sophisticated bot farms out there that gets around detection, mostly operated out in Eastern Europe and Asia. If you look at Comscore 100 video sites, you can always tell who's gaming the system when from one month to next, an unknown brand just jumped high in the top 100.<p>This is the reason Facebook had shut down Liverail that they spent $450M on. Super high percentage of ad fraud.