Nyse

Wall Street_Lea.jpg

** FILE ** Trader Stephen Holden (center) works with other traders at the post that handles Wal-Mart on the floor of the New York Stock Exchange on Monday, April 23, 2012. (AP Photo/Richard Drew)

Wall Street_Lea.jpg

** FILE ** Trader Damian Bagarozza (left) and specialist Joseph Mastrolia work on the floor of the New York Stock Exchange on Monday, April 16, 2012. (AP Photo/Richard Drew)

Wall Street_Live.jpg

Trader Michael Zicchinolfi (right) works April 23, 2012, on the floor of the New York Stock Exchange. (Associated Press)

** FILE ** Specialist Dermot Bermingham (second from left) and trader Thomas Kay (foreground at right) work on the floor of the New York Stock Exchange on Tuesday, April 17, 2012. (AP Photo/Richard Drew)

APTOPIX Wall Street_Live.jpg

Trader Stephen Mara (center) works April 17, 2012, on the floor of the New York Stock Exchange. (Associated Press)

Earns Goldman Sachs_Live.jpg

**FILE** A trader works in the Goldman Sachs booth on the floor of the New York Stock Exchange on March 15, 2012. (Associated Press)

Wall Street_Live.jpg

Steven Kaplan (right) works April 16, 2012, with fellow traders on the floor of the New York Stock Exchange in New York. (Associated Press)

WALLSTREET.jpg

Specialist Robert Tuccillo (center) works with traders on the floor of the New York Stock Exchange on Monday, April 9, 2012. Stocks opened sharply higher on Wednesday, a day after their worst loss of the year. (AP Photo/Richard Drew)

Wall Street_Lea(1).jpg

Trader Luigi Muccitelli (left) and specialist Jennifer Klesaris work on the floor of the New York Stock Exchange on Monday, April 9, 2012, in New York. (AP Photo/Richard Drew)

Wall Street_Lea.jpg

Damian Bagarozza (right) works with fellow traders on the floor of the New York Stock Exchange on Monday, March 19, 2012, in New York. (AP Photo/Richard Drew)

Wall Street_Lea.jpg

Specialist Michael Scavone works at his post on the floor of the New York Stock Exchange on Thursday, March 15, 2012, in New York. (AP Photo/Richard Drew)

Wall Street_Lea.jpg

Traders work on the floor of the New York Stock Exchange on Tuesday, March 6, 2012, in New York. (AP Photo/Seth Wenig)

Wall Street_Live.jpg

Traders David O'Day (left) and Neil Catania confer on the floor of the New York Stock Exchange on March 2, 2012. (Associated Press)

YELP.jpg

** FILE ** Jeremy Stoppelman, right center, Yelp co-founder and CEO, salutes during opening bell ceremonies of the New York Stock Exchange Friday, March 2, 2012. Yelp's stock is soaring in its stock market debut Friday. (Associated Press)