John Thain, chief executive officer of NYSE Group, Inc., sec

UNITED STATES - MARCH 08: John Thain, chief executive officer of NYSE Group, Inc., second from left, stands on the bell podium with fellow NYSE Group executives Gerald Putnam, president and co-chief operating officer, left, Marshall Carter, chairman, second from right, and Catherine Kinney, president and co-chief operating officer, prior to ringing the opening bell on the floor of the New York Stock Exchange Wednesday, March 8, 2006 in New York. Shares of the New York Stock Exchange climbed as much as 12 percent in their trading debut, underlining investor confidence in the future of the world's largest equity market as a public company. (Photo by Daniel Acker/Bloomberg via Getty Images)