Update, 12/18/2012, 5:30 p.m. EST: This article has been revised to include the names of the Morrison & Foerster attorneys leading the firm’s team advising Arbitron in connection with Nielsen Holdings’s acquisition of the company.

In a deal that brings together two of the leading systems for tracking the habits of media consumers, television-ratings stalwart Nielsen Holdings said Tuesday it has agreed to pay $1.26 billion to acquire radio-ratings and media research company Arbitron Inc.

Terms of the transaction call for Nielsen—which is known for tallying what TV viewers are watching—to pay $48 in cash for each share of Columbia, Maryland–based Arbritron. That price represents a 26 percent premium over Arbitron’s Monday closing price.

In announcing the deal, Nielsen said that acquiring Arbitron will increase its ability to track consumer behavior, including adding to its capacity for measuring the habits of listeners who stream audio online. In October, Nielsen launched a much-anticipated campaign to track programming performance across multiple platforms, incorporating online streaming statistics into its existing ratings systems for television and radio consumption.

Nielsen has turned to frequent counsel Simpson Thacher & Bartlett for legal advice on the transaction. Last year, the firm advised Nielsen on its $1.64 billion initial public offering and has handled a number of past acquisitions, including Nielsen’s 2007 purchase of consumer research rival Telephia Inc. for an undisclosed amount.

The Simpson Thacher corporate team handling the Arbitron purchase is led by New York corporate partners Gary Horowitz and Marni Lerner. Nielsen’s chief legal officer is James Cuminale.

A Davis Polk & Wardwell team led by M&A partner Phillip Mills is advising J.P. Morgan Securities in connection with its role as Nielsen’s financial adviser on the transaction.