So long and thanks for all the ads! Here's why Microsoft is exiting the $74 billion display advertising business
In the US, Facebook is the biggest seller of display advertising, estimated by eMarketer to take a 25% share of the market in 2015. Google will have a 15% share, eMarketer predicts.
http://uk.businessinsider.com/why-microsoft-is-exiting-the-display-advertising-business-2015-6