• by Erik Sass  @eriksass1, January 3, 2013

Arbitron has won over one of the last major holdouts for its radio ratings service, with Thursday's announcement that Cumulus Media signed a deal for ratings covering 450 of Cumulus’ 525 radio stations in 100 media markets across the U.S.

The deal includes diary ratings for 44 Cumulus Media markets where Cumulus radio audiences have not been measured by Arbitron since 2009. The deal also renews their agreements for radio ratings in 17 markets measured by Arbitron's Portable People Meter, as well as 39 diary markets.

Cumulus is working with Arbitron on a cross-platform measurement service that will presumably include quantifying streaming and mobile audiences.

In previous years, Cumulus execs had criticized Arbitron for holding a monopoly in the radio ratings business; in 2008, Cumulus Chief Operating Officer John Dickey issued an RFP for an alternative measurement system for small and midsized markets that could compete with Arbitron's diary service, but nothing apparently came of this initiative.

The Cumulus-Arbitron deal comes just a few weeks after the announcement that Arbitron is being acquired by fellow media research giant Nielsen, a longtime competitor and sometimes partner in the media ratings marketplace. At the time, Nielsen CEO David Calhoun stated: "Arbitron will help Nielsen better solve for unmeasured areas of media consumption, including streaming audio and out-of-home. The high level of engagement with radio and TV among rapidly growing multicultural audiences makes this central to Nielsen's priorities."

However, the deal has sparked some concern that the combined entity will wield even greater monopolistic power in media ratings than the already-considerable clout the companies wielded separately.