Economic studies of advertising traditionally assume perfect competition and a single market-clearing price. This assumption can result in misleading business and policy conclusions because it holds only if advertisers do not care about the extent to which different media outlets duplicate each other’s audiences, which is not very likely. This empirical analysis on the radio advertising market presents evidence challenging this traditional view. It shows that ad price increases with audience exclusivity (i.e., non-duplicative audience. As media fragmentation and measurement technology continue to develop, this finding suggests a more important role for exclusive audience and targeting in the age of online media.