Investment in Affiliates (Tables)

6 Months Ended

Jun. 30, 2014

Investments in and Advances to Affiliates, Schedule of Investments [Abstract]

Investments in and Advances to Affiliates

At June 30, 2014 and December 31, 2013, the investments in affiliates were composed of the following (in thousands):

	June 30, 2014		December 31, 2013
Investment in OCC	$	333	$	333
Investment in Signal Trading Systems, LLC	11,260		11,130
Investment in IPXI Holdings, LLC	3,118		3,118
Investment in CBOE Stock Exchange, LLC (1)	—		—
Investments in Affiliates	$	14,711	$	14,581

(1) CBOE Stock Exchange, LLC ceased trading operations on April 30, 2014.