OSD revenue increased primarily as a result of growth in online advertising revenue. Online advertising revenue grew $358 million or 19% to $2.3 billion, reflecting continued growth in search and display advertising revenue, offset in part by decreased third party advertising revenue. Search revenue grew due to increased volumes reflecting general market growth, relative share gains in the U.S., and our Yahoo! alliance, offset in part by decreased revenue per search primarily related to challenges associated with optimizing the adCenter platform for the new mix and volume of traffic from the combined Yahoo! and Bing properties. As of June 30, 2011, according to third-party sources, Bing organic U.S. market share grew over 31% to approximately 14%, while Bing-powered U.S. market share, including Yahoo! properties, was approximately 27%.
OSD operating loss increased due to higher operating expenses, offset in part by increased revenue. Cost of revenue grew $641 million driven by costs associated with the Yahoo! search agreement and increased traffic acquisition costs. General and administrative expenses decreased $157 million or 60% due mainly to transition expenses in the prior year associated with the inception of the Yahoo! Commercial Agreement. Research and development increased $117 million or 11% due to increased headcount-related costs.