Why Do Stocks Go Up and Down?

Charles Biderman, the president and CEO of Trim Tabs Asset Management, tells Pimm Fox and Lisa Abramowicz why stock prices move in one direction versus another. Ron Sanchez, the chief investment officer at Fiduciary Trust Company Internation, talks about global investing and which global economy is growing the fastest. Finally, Bloomberg Intelligence's Poonam Goyal discusses news that Wal-Mart's e-commerce sales are surging as it plays catch-up with Amazon.