It started trading at $43.00 and ended at $38.23 which is a -8.39% loss. Why is the IPO price $38.00 if it started trading at $43.00?
So, this morning when it started trading, the first order seems to have been $42.05 (according to Google) with subsequent orders fluctuating from there. The LA Times is reporting (http://www.latimes.com/business/technology/la-fi-tn-facebook...) that the companies who underwrote the IPO (for example, Morgan Stanley) had to defend the price so that it didn't drop below $38 during trading today. Basically, one can do this by offering to buy shares at $38. That way, their clients who bought yesterday at $38 don't suffer a loss today as the stock is actively traded.