TV TO RADIO: Nielsen, the dominant source of TV ratings, is buying Arbitron for about $1.26 billion to expand into radio measurement.
BIG PREMIUM: Nielsen Holdings N.V. will pay $48 per share, a 26 percent premium to Arbitron's Monday closing price. Nielsen plans to spread Arbitron's tracking technology to countries outside of the U.S.
LONG HISTORY: Nielsen was the prime source of audience ratings in the early days of radio, thanks to a device similar to Arbitron's People Meter. The Audimeter was attached to the radio set. The company's focus shifted to TV measurement in the 1950s.
- TV ratings