Not surprisingly, Google has the largest share of the ad server market. However, it may be striking that Microsoft has only a small part.
According to an article published this month in CNET News, Attributor, a content tracking company, analyzed calls to ad servers for 75 million domains in October. Yahoo lags behind Google at 9.7%, which means that if Microsoft and Yahoo were to combine forces, they would still fall short of Google.
By way of clarification, a call to a server is the “moment when a website requests an advertisement to present to the user”. According to AdAge.com, "the study examined who the page's advertising code belonged to."
Based on Attributor figures, DoubleClick and AdSense are definitely targeting different markets. DoubleClick dominates on larger sites, while AdSense dominates on smaller ones.
However, not all is good news for Google. Last January, when Attributor last looked at calls to ad servers, Google's AdSense and DoubleClick services accounted for 69.7% of market share, a drop of more than 13 points compared to the current figure.
However, Google did not lose ground to Microsoft or Yahoo, as they also lost share, but it did so to other competitors, including AOL and Revenue Science. The latter managed to sneak into the top five, with a 6.7% market share in October.