Relevance & Research Question: Numerous ad-tech companies track and analyze the online behavior of internet users with the objective of placing targeted and/or personalized advertising. In order to prospect users with specific interests or to retarget users from prior website visits, ad-tech agencies rely on tracking technology, mainly cookies. While users browse the internet, an invisible network of third-party servers is called to deliver advertising based on waste amounts of data. In this research, we uncover this invisible network of tracking servers in order to gain an understanding of the state of the ad-tech industry.

Methods & Data: This study uses an innovative approach to research a B2B market: We have collected more than 100.000 lines of server calls in 80 browsing sessions of students of a German university. The data is collected using the Lightbeam Firefox Plugin. The calls of third party servers were classified as asset servers, analytics servers, advertising servers and widgets using Python scripts on an SQL database.

Results: Not surprisingly, we find that Google’s and Facebook’s third party servers are called by 78%/34% of sites per user. Consequently Google and Facebook are in an excellent position to track online user behavior and offer targeted, personalized advertising. On the other hand, most of the other 1.000+ tracking servers (some belonging to one company) are called by so few internet sites, that personalized advertising is technically impossible. As our study underlines the strong dependence of advertisers on Google and Facebook we argue, that those companies will continue to absorb strong shares in the advertising market. On the other hand we predict a consolidation of the “long-tail” of ad-tech companies that are too small to be present

Added Value: This paper describes the tracking methodologies used to enable targeted and personalized advertising. This paper also provides the reader with a description of an alternative data collection methodology which can be used for researching consumer behavior or company strategies.