Known by the nickname "Wall Street," Curtis Carroll teaches financial literacy at the San Quentin Prison, helping inmates prepare for life after incarceration. Carroll, however, is serving a life sentence. Courtest of The California Department of Corrections and Rehabilitation hide caption

itoggle caption Courtest of The California Department of Corrections and Rehabilitation

A trader stands outside the New York Stock Exchange on Oct. 31, 2012. Timothy A. Clary/AFP/Getty Images hide caption

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A New York Stock Exchange trader works on the floor on Dec. 17. Stocks rose nearly 300 points after the Federal Reserve announced it plans to begin raising interest rates next year. Andrew Burton/Getty Images hide caption

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While traders may still roam the floor of the New York Stock Exchange, there's unseen action taking place every millisecond via fiber optic cables connecting computers run by trading firms and computers run by the Exchange. Andrew Burton/Getty Images hide caption

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Former SAC portfolio manager Michael Steinberg (center) exits a Manhattan federal court with his attorney after his indictment on securities fraud charges in March. Louis Lanzano/AP hide caption

itoggle caption Louis Lanzano/AP

Federal Reserve Chairman Ben Bernanke during a news conference in June. Financial markets reacted to comments he made then by selling off bonds and stocks. Alex Wong/Getty Images hide caption

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Mary Jo White, then U.S. Attorney for the Southern District of New York, speaks during a May 2001 press conference following guilty verdicts in the trial of four followers of Osama bin Laden that bombed two U.S. embassies in East Africa in 1998. President Obama intends to nominate White to head the Securities and Exchange Commission. Doug Kanter/AFP/Getty Images hide caption

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Investors and financial analysis firms are increasingly looking at "sentimental analysis" — such as Facebook "likes" and Twitter messages — to gauge a company's social popularity. iStockphoto.com hide caption

itoggle caption iStockphoto.com

Note: Totals may not add up to 100 percent, due to rounding. Alyson Hurt /NPR hide caption

itoggle caption Alyson Hurt /NPR