Remember when financial columnist Mark Hulbert suggested that Facebook shares should cost $13.80? Well, it's looking more and more likely. Shares dipped below $20 in trading today, at one point hitting $19.90, according to the Wall Street Journal. "There's huge negative sentiment and there hasn't been a counter to that," says one analyst. That analyst, incidentally, has rated Facebook as a "buy," but doesn't expect it to regain its $38 IPO price until the end of next year.