Billionaire investor Carl Icahn, center, walks outside of the Nasdaq MarketSite with Robert Greifeld, chief executive officer and president of Nasdaq OMX Group Inc., in New York. Photographer: Scott Eells/Bloomberg
Billionaire investor Carl Icahn, center, walks outside of the Nasdaq MarketSite with Robert Greifeld, chief executive officer and president of Nasdaq OMX Group Inc., in New York. Photographer: Scott Eells/Bloomberg