At MarketWatch, Mark Hulbert crunches the numbers and predicts
Actually, however, the news is even worse: No one is going to invest in Facebook shares today if its price will be 30% lower in five years. So, in order to entice someone to invest in it today, Facebook needs to offer a handsome return. Assuming that its five-year return is equal to the stock market’s long-term average return of 11% annualized, Facebook shares currently would need to be trading at just $13.80.
Follow the link for the how-to of his reasoning.