New submitter fierman writes "In a work to be presented at the Network and Distributed System Security Symposium (ISOC NDSS'14), INRIA researchers show the privacy risks of Real-Time Bidding (PDF) and High-Frequency Trading for selling advertisement spaces. Combining Real-Time Bidding and Cookie Matching, advertisers can significantly improve their tracking and profiling capabilities. Both technologies are already prevalent on the Web. The research discusses the value of users' private data (browsing history) retrieved directly from the advertisers, leveraging an exposed information leak in RTB systems. Advertisers will pay about $0.0005 to display a targeted ad to a single user, while at the same time acquiring information about them. The research also shows evidence of price variation with users' profiles, physical location, time of day and content of visited sites."