  Digital advertising is the most popular way for content monetization on the
Internet. Publishers spawn new websites, and older ones change hands with the
sole purpose of monetizing user traffic. In this ever-evolving ecosystem, it is
challenging to effectively answer questions such as: Which entities monetize
what websites? What categories of websites does an average entity typically
monetize on and how diverse are these websites? How has this website
administration ecosystem changed across time?
  In this paper, we propose a novel, graph-based methodology to detect
administration of websites on the Web, by exploiting the ad-related
publisher-specific IDs. We apply our methodology across the top 1 million
websites and study the characteristics of the created graphs of website
administration. Our findings show that approximately 90% of the websites are
associated each with a single publisher, and that small publishers tend to
manage less popular websites. We perform a historical analysis of up to 8
million websites, and find a new, constantly rising number of (intermediary)
publishers that control and monetize traffic from hundreds of websites, seeking
a share of the ad-market pie. We also observe that over time, websites tend to
move from big to smaller administrators.
