Nielsen Holdings NV (NLSN), the biggest tracker of U.S. television ratings, won approval from the U.S. Federal Trade Commission for its $1.26 billion acquisition of Arbitron Inc. (ARB)

Clearance of the deal requires Nielsen to sell and license assets related to Arbitron’s audience-measurement services for different forms of media under a settlement reached with the agency, according to a statement yesterday.

“The evidence provided us with a strong reason to believe that absent a remedy, the deal was likely to harm emerging competition in the area of cross-platform audience measurement,” FTC Chairwoman Edith Ramirez said.

Nielsen — controlled by private-equity investors, including KKR & Co. (KKR) — makes money by helping advertisers, consumer-goods manufacturers, retailers and other companies figure out how to spend their marketing dollars. The company said that private-equity ownership “stands at 41 percent.

Nielsen is seeking to offer advertisers a unified system of measuring audiences across multiple forms of media, making it easier for them to make ad-buying decisions whether on TV, radio or the Internet. The New York-based company, whose ratings help set rates for $70 billion in U.S. television advertising, announced its acquisition of Arbitron in December. Arbitron measures radio audiences.

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