Yahoo will pay about $640 million for automated advertising service BrightRoll, beefing up its ability to sell video ads in real-time to marketers in a bid to offset declining Internet ad prices and decelerating growth.

The acquisition sustains chief executive officer Marissa Mayer's acquisition spree and sharpens the company's focus on video ads.

Buying BrightRoll, which is profitable and expected to have revenues of more than $100 million this year, will make broadly extend Yahoo's video advertising platform and  make it the largest in the US, the company said in a statement. – Reuters