Arbitron this week said Clear Channel Radio renewed its agreements for Portable People Meter and diary ratings services.

The early signing and its scope caught the attention of stock analyst Jim Boyle of Gilford Securities, who said the agreement was to have expired a year from now.

“This would have hung over [Arbitron] in 2011 like Derek Jeter’s contract negotiations hung over the N.Y. Yankees,” he wrote to clients in an e-mail. To renew for six years and a reported $538 million, and to do so much earlier than expected, is a Christmas gift to Arbitron investors, Boyle said, and should pressure other radio companies to renew with Arbitron rather than “defect.” He bumped up his stock outlook target for Arbitron as a result.

He added that there have been no Arbitron client defections in more than two years and noted that PPM deals start to renew in 2012–13. “Can Nielsen get a few big-market defectors?” he wondered.

Clear Channel is Arbitron’s largest radio ratings subscriber and represented approximately 19 percent of Arbitron’s revenue in 2009. The deal extends Clear Channel’s access to Arbitron ratings and other services in all of the broadcaster’s markets through the end of 2016.

How much does Clear Channel pay Arbitron per year for its ratings? The contract averages to $89.6 million; Boyle estimates it will be around $83 million in 2011, escalating to $96 million by the end of the contract.