HONG KONG — News that Goldman Sachs has taken a $450 million stake in Facebook in a deal that puts a $50 billion valuation on the fledgling company raises interesting and somewhat troubling questions beyond the immediate gawping and jaw-dropping headlines that a spotty-faced Harvard dropout aged 26 is not only Time's "Person of the Year," but is also worth $12 billion plus (based on Mark Zuckerberg's 24 percent stake in Facebook).

Is Facebook really worth $50 billion, near the market value of Boeing, or more than the value of Goldman's rival Morgan Stanley? It is difficult to know when Facebook has not made any accounts public. According to the stock-sale memorandum prepared by Goldman, Facebook's 2009 revenues were $775 million and profits were $200 million. In 2010, revenues rose to $2 billion, and profits to $500 million, so the valuation is 25-times revenue (against Google's valuation of seven-times revenue).

The very fact that Goldman Sachs and Facebook had "friended" each other prompted other rich people to consider buying Facebook shares. San Francisco newspapers reported earlier this month that the private shares market Sharespost sold 165,000 shares for $25 each in a "significantly oversubscribed auction," valuing the company at $56 billion. A well-known analyst was quoted as saying that by 2015 Facebook could easily be worth $200 billion.