Recent statistics show that pop-under ads generate more traffic than
pop up ads. Pop-up ads open a new window in front of your current browser window and are as such considered very intrusive and annoying. Pop under ads on the other hand appear below your current web page allowing you to continue browsing without interruptions. You will only notice the ad when you close or minimize the webpage you are working on. This feature makes them less annoying to web browsers. They allow you to prioritize what took you to that particular site then tend to them later at your own convenience.
Content on pop-under ads is also more likely to recieve more attention than that on pop-up ads. This is because they do not demand a web user’s immediate attention that is in most cases focused elsewhere. Besides, pop under ads have more time to load their content such that by the time they are attended to, the user sees a complete web page. This is in contrast to a pop-up ad that is more likely to promptly get closed by an annoyed user before it can load its content.
Another reason why pop-under ads generate more traffic than their counterparts is that there are less mechanisms in browsers and antivirus programs to block them as compared to pop-up ads. Most browsers nowadays block pop-up ads completely and in so doing greatly reduce the amount of traffic they generate. Pop-under ads can be blocked by browsers too, but that would require advanced configurations and settings which are unknown to the average user. Consequently, they are more likely to be seen than pop-up ads. Pop-up ads exploit security vulnerabilities in browsers to circumvent blocking but these bugs are slowly and surely being fixed. Pop-under ads are surely the way to go because they are convenient to both advertisers and web users.