As Facebook updates its status from a privately held to a publicly listed company this year, shares of its friends in the Global X Social Media Index ETF (SOCL) are rallying in anticipation of the biggest IPO since Google (GOOG). But while the rising tide may be lifting all boats, the market could quickly unfriend these stocks once the enthusiasm dies. After rising 9% in January, the ETF has climbed 4.9% this month vs. 2.5% for the S&P 500. Among