Although Zuckerberg stressed that "graph search" is different from an all-purpose search engine, the expanded feature escalates an already fierce duel between Google Inc. and Facebook Inc., as they grapple for the attention of Web surfers and revenue from online advertisers.
"This could be another reason not to use Google and another reason to stay on Facebook for longer periods," said Gartner analyst Brian Blau. "I don't think Google is going to lose its search business, but it could have an impact on Google by changing the nature of search in the future."
Facebook's foray into search marks one of its boldest steps since its initial public offering of stock flopped eight months ago amid concerns about the company's ability to produce the same kind of robust earnings growth that Google delivered after it went public in 2004.
Although Facebook's stock has rallied in recent weeks, the shares remain below their IPO price of $38. Investors seemed let down by Tuesday's news, causing Facebook's stock to slip 85 cents, or 2.7 percent, to close at $30.10.
If the new search tool works the way Facebook envisions, users should be able to find information on their own instead of relying on the social network's formulas to pick which posts and pictures to display in their feeds, analysts said.