AOL's value isn't reflected in Time Warner's share price, says Henry Berghoef, director of research at Chicago-based Harris Associates, which owns shares of Time Warner. "Given where Time Warner's stock is trading these days, AOL represents a free option on a potentially very interesting value," he said in an interview. "I would like Time Warner to do what creates the greatest value for shareholders." In part, Microsoft wants to get a piece of America Online to thwart the ambitions of Google, which provides search services for the Time Warner service. The software giant also wants to boost the popularity of its MSN Internet service, which lags Yahoo! and Google in users. Yahoo! has decided against bidding for a stake in AOL, a company spokeswoman says. In an interview with The New York Times, Microsoft Chairman Bill Gates said the company was interested in AOL to take advantage of the surging interest in Internet advertising. A Microsoft spokeswoman declined to comment Thursday. "We think that it's more important that Microsoft gets this than Google," says Daniel Poole of National City, which owns shares of Google, Microsoft and Yahoo!. "It's a very close battle." Google, which gets about 11% of its revenue from advertising on AOL, also has the resources to buy AOL to beat back any challenge from Microsoft. The Mountain View, Calif.-based search giant also has other ambitions, including broadening its reach in the advertising business. That concept may interest it more than acquiring AOL, says Martin Pyykkonen, an analyst with Hoefer & Arnett who has a buy rating on Google and a strong buy rating on Yahoo!. He doesn't follow Microsoft. "AOL is a great distribution partner for them and they clearly would like to keep them if they could," he said. Google declined to comment.