Facebook's long-anticipated initial public offering has reportedly been set for May 18, sources told The Wall Street Journal on Tuesday. The social-networking company will hit the road on Monday to start pitching the stock to investors. Mark Zuckerberg will attend some of the meetings but isn't expected to be at all of them. Analysts estimate Facebook, which has about 900 million monthly users, could raise as much as $10 billion by going public, which would make it one of the largest tech IPOs of all time. The company recently posted its first-quarter earnings, hauling in $1 billion so far this year, though seeing a small snag in its growth.