Signage is displayed on the main building of the University of Phoenix, part of Apollo Group Inc., in Phoenix, Arizona, U.S., on Thursday, Oct. 14, 2010. Apollo Group, the biggest U.S.for-profit college by enrollment, led education shares to their biggest plunge in more than 5 years today after executives described a bleak future for signing up new students. Photographer: Joshua Lott/Bloomberg via Getty Images