The most highly anticipated IPO in history didn’t put on much of a show. Facebook closed today within decimal points of its opening price of $38. Even so, the company’s market cap is higher than McDonald’s or Pepsico. Espen Robak is the president of Pluris Valuation Advisors, where he studies and values private companies trading on the secondary market. Derek Thompson at The Atlantic talked to him this morning right as Facebook trading began.   One of Robak’s first points was “The people who bought in the secondary market came in right around $44. Those shares are locked for 180…