XML 42 R21.htm IDEA: XBRL DOCUMENT

Customer Concentration	12 Months Ended
Dec. 31, 2011
Customer Concentration [Abstract]
Customer Concentration	15. Customer Concentration During the years ended December 31, 2011, 2010 and 2009, no single client accounted for more than 10% of total revenue. One institutional investor client accounted for approximately 14.6%, 15.8% and 12.1% of trading volumes during the years ended December 31, 2011, 2010 and 2009, respectively. This institutional investor client also beneficially owns approximately 5% of the outstanding shares of the Company’s common stock.

Customer Concentration

12 Months Ended

Dec. 31, 2011

15. Customer Concentration

During the years ended December 31, 2011, 2010 and 2009, no single client accounted for more than 10% of total revenue. One institutional investor client accounted for approximately 14.6%, 15.8% and 12.1% of trading volumes during the years ended December 31, 2011, 2010 and 2009, respectively. This institutional investor client also beneficially owns approximately 5% of the outstanding shares of the Company’s common stock.