A trader works at the Knight Capital Group Inc. booth on the floor of the New York Stock Exchange (NYSE) in New York, U.S., on Tuesday, Aug. 7, 2012. U.S. stocks advanced, sending the Standard & Poor?s 500 Index higher for a third straight day, amid better-than-estimated corporate earnings and speculation global central banks will take steps to boost economic growth. Photographer: Jin Lee/Bloomberg via Getty Images