Facebook may yet be overpriced. Morgan Stanley and its fellow underwriters of the IPO undoubtedly spent millions of dollars, maybe hundreds of millions, propping up the stock Friday so it wouldn’t fall below the $38 offering price, as that would have been a huge embarrassment. No one knows how long they’d continue to do so.

Additionally, in about a week the shares become eligible for short-selling, which could place more pressure on the price. A few months from now, insiders prohibited from selling their own share will have the green light, and millions more shares will enter the marketplace. The question in coming weeks may no longer be how high Facebook can soar, but how low can it go?