The new talk format, billed as a hybrid of politics, sports and pop culture, will be heard on nine Infinity stations.

You start the day listening to radio and that's an Infinity station.

You listen to another Infinity station on the drive to work, and while traveling you see billboards owned by Viacom/CBS.

The sheer concentration of Infinity stations in each market has also enabled Mr. Karmazin to command premium prices for advertising.

This involves selling ads across several Infinity stations in an area, instead of requiring the stations to compete with one another.

Mr. Sykes said he offered the Letterman show to a wide range of Infinity stations.

But the broader fallout could be substantial, as Infinity stations find themselves in need of a new identity, jeopardizing sales and ratings.

And when a National theater did a live broadcast of the Red Sox-Yankees game, it was promoted on a local Infinity station.

Infinity stations have two of the best-known and highest-paid performers in radio, Don Imus and Howard Stern.

Upon review, Infinity received a collective $200,000 fine on May 20, with the four Infinity stations being given penalties of $50,000 each.