Nielsen agrees to buy Arbitron for $1.26 billion

Nielsen said Tuesday that it agreed to buy Arbitron for $48 per share in cash, which values the top radio ratings firm at $1.26 billion.

The deal comes as Nielsen faces increased competition from Rentrak, which uses data collected from cable and satellite TV set-tops to sell marketers ratings reports. Nielsen also faces competition from ComScore, which has developed a multiplatform measurement service.

Last month, Nielsen acquired SocialGuide, which tracks conversations on Twitter about TV shows. Nielsen announced late Monday that it would team up with Twitter to create "Nielsen Twitter TV Rating" reports. The first reports are expected to be released next fall.

Nielsen CEO David Calhoun said on a conference call Tuesday morning that Nielsen would use the Arbitron acquisition to help marketers determine the "best marketing mix" to reach consumers watching TV or listening to radio programs, noting that the merger wasn't focused on developing new cross-platform measurement tools.

"We will seek to provide cross platform solutions among other players to our specific client needs, but that is not why we are doing this transaction," Calhoun added.