"If Yahoo's Right Media exchange is structured like a financial market, OpenX Market is more analogous to a search marketplace," said Tim Cadogan, CEO of OpenX.

And Cadogan should know. Before joining OpenX one year ago, he spent five years at Yahoo, ultimately serving as its SVP of global advertising marketplaces, including display, search and video.

Publishers will now be encouraged to route their ad impressions into the OpenX Market through tools that are already integrated into OpenX's established ad server. After publishers define a minimum "floor" price for their ad impressions, the market then runs a real-time auction for each impression.

"That's another key differentiator for us," said Cadogan. "We don't set the minimum fee for publishers to participate."

If the winning bid from the auction is higher than the publisher-set minimum price, the higher-paying ad is served and the publisher makes more money. If the winning bid is less, meanwhile, the publisher's original ad runs.

Headquartered in Pasadena, Calif. with offices in London and Poland, OpenX's primary product is an independent ad server, which is used by some 35,000 publishers on more than 150,000 Web sites online.

The company estimates that roughly 300 billion ad impressions run through its OpenX software every month -- about a third of which come from U.S. Web users. Rivals include the DoubleClick-backed Google Ad Manager, AdMeld, Pubmatic, and the Rubicon Project.

Along with its existing market presence, Cadogan is confident that the new market's simplicity, openness and independence will guarantee success. "We are fully integrated to handle premium and remnant advertisings, and can work with agencies, direct advertisers, and ad networks," Cadogan said.

Backed by Accel Partners, Index Ventures and O'Reilly AlphaTech Ventures, OpenX has raised $20.5 million to date.

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