Facebook will acquire LiveRail, a video-advertising technology company, as the social giant looks to dramatically expand its video advertising business.

Terms of the deal were not disclosed. Customers of LiveRail, founded in 2007, include Major League Baseball, CBS Interactive, ABC, A+E Networks, Gannett, Dailymotion and Songza. The company claims it delivers more than 7 billion ad impressions monthly.

"We believe that LiveRail, Facebook and the premium publishers it serves have an opportunity to make video ads better and more relevant for the hundreds of millions of people who watch digital video every month," Brian Boland, Facebook's VP of ads product marketing, said in announcing the deal.

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LiveRail operates a real-time bidding advertising system, designed to let digital-video publishers place ads in a "programmatic" fashion based on multiple criteria at the optimal price.

Facebook -- which touts its base of 150 million daily active U.S. users as offering greater reach than TV -- launched its Premium Video Ads service with a test last December for Summit Entertainment's "Divergent" and opened it up to a select group of marketers this spring. In May, NBC became the first TV network to use the Facebook autoplay video ads to promote three midseason shows: "Rosemary's Baby," "The Night Shift" and "Undateable."

LiveRail, based in San Francisco, has 170 employees. The company's main investor is venture-capital firm Pond Ventures.

"We believe that LiveRail's excellent product -- known in the industry as a video supply-side platform or SSP -- and Facebook's expertise with relevancy, delivery and measurement will help us make video advertising much better for everyone," Boland said.

Separately, Facebook is in hot water over a 2012 test it conducted with 700,000 unsuspecting users, in which it altered the posts that appeared in their newsfeeds to gauge how emotional sentiment spread on the network. Facebook COO Sheryl Sandberg has apologized for the test, the Wall Street Journal reported. This week the U.K.'s Information Commissioner's Office, which regulates data-privacy laws in the country, said it is investigating the experiment.

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