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Analysts say that allowing Google to serve its ads on Yahoo search pages would immediately boost search revenues by a third and Yahoo's stock by $5 a share. Problem is, Microsoft's top lawyer, Brad Smith, already promised to make a regulatory stink about such a deal, saying it would give Google control over 90 percent of the search advertising market. But a source involved with the discussions between Yahoo and Google says there's a way Yahoo could steer clear of antitrust trouble.

The answer is to create an open marketplace for its search results, inviting Google and Microsoft to bid on placing ads on them. Yahoo might even keep its own search-marketing platform up and running. It's just the kind of open-with-a-capital-O move Yahoo president Sue Decker likes to talk about on quarterly analyst calls. Of course, that assumes Google values keeping Yahoo out of Microsoft's control more than an exclusive deal for all of Yahoo's search business. Which, come to think of it, it likely does.