How much public information is available on what companies are underwriting public radio? I was looking at NPR's IRS 990 on Guidestar, but it doesn't list any kind of breakdown as to how it is underwritten. Is this public info?
The Columbia Journalism Review's Who Owns What? database is invaluable for this sort of question. Although I can't get it to spit out a list, you can go through and check manually on each company's ownership of different types of media.
I checked through the Cs and so far came up with CBS, Citadel Broadcasting, Clear Channel, Corus, Cox, and Cumulus as outfits that own more than 25 radio stations.
