The new U.S. auction market for radio advertising will go live Wednesday and include both conventional terrestrial radio and Internet radio advertising. Stations in all of the 300 top-ranked radio markets are covered, eBay said.
"Available inventory is determined by participating radio stations and what they choose to sell for the next week," eBay spokeswoman Kim Rubey said.
She said the available advertising inventory includes primetime spots. Some 90 percent are in morning "drive time," midday or evening commute hours from Monday through Friday.
Ahead of the radio advertising announcement, shares of eBay dropped 85 cents, or 2.61%, to close at $31.69 in regular session trade on Nasdaq. The stock edged higher in extended trade to $31.75, up 6 cents, following the news.
EBay has said it sees the hundreds of thousands of sellers in its online auction markets as potential advertisers within the media marketplaces it is seeking to develop.
Its cable TV advertising auction push has met with some resistance from cable operators who fear the auctions could put stiff pressure on advertising rates.
EBay created the cable TV ad marketplace last year with 10 corporate advertisers, including Toyota Motor , Home Depot , Hewlett-Packard, Intel and Microsoft . Advertising agency representatives from Magna Global, Omnicom Group and Carat USA are also taking part in the effort.
But the Cable Television Advertising Bureau, an industry trade group that represents large, ad-supported cable channels, withdrew from trials of the eBay Media Marketplace in April, complaining the system was unworkable.
Last week, however, women-oriented cable network Oxygen became the first cable programmer to agree to use eBay's "Media Marketplace for Cable TV" to sell planned, advertising spots nationwide.
By contrast, EBay's own radio auctions target last-minute ad buyers. "This flexibility enables stations to be extremely aggressive in their pricing," an eBay spokesman said.