In response to Google's purchase of DoubleClick, Yahoo purchased Right Media's ad exchange for $680 million. From Yahoo!'s press release blog post:
We think supply and demand should be regulated by the marketplace, not a closed platform. Right Media provides a democratic model that empowers advertisers with all of these benefits. We think our open approach is a clear differentiator from others in the industry and will provide significant benefits to publishers and advertisers.
One wonders why the Yahoo! Publisher Network is still in beta, why Yahoo! stopped showing bid prices, and why the Panama ad system is US/Canada only if Yahoo! is so into being open. Democracy as a marketing story for search worked...not so sure if it matters for advertising though.