facebook is valued at 41 Billion $

Facebook is valued at 41 Billion U.S $, according to trades in secondary markets (the IPO is still to come). This means that Facebook is currently the 3rd largest Internet business corporation in the U.S, trailing only Amazon and Google. I have to disagree with the source of this item regarding the importance. The value in secondary market is not unrelated to real economic value. If at all, then this value includes some discount, because of the lower transferability/merchantability of ownership-units traded in secondary markets. Considering the immensely high value that is traditionally given to the number of users/members/subscribers an internet company has, one would expect Facebook's 500 million users to be of a higher value. If we would assume that secondary markets are rationale (an assumption usually made about stock markets as well, without a lot of proof, I claim) It would appear that this valuation is also based on certain risks and difficulties the secondary market sees in facebook. It seems that quick rise and fall of myspace, and the fluent nature of users and members along the social networks, are taken into account in the valuation of facebook. It might also be that the valuation takes into account the variety of fields in which these internet giants are operating. Amazon just announced its entry into the movie making field, with what appears to be a very interesting business model. In such circumstances, with rivals loaded with talent and money, one's moat - competitive edge - might never be deep enough...