Michael Mussio, a portfolio manager at FBB Capital Partners, says phones have been ringing more than normal in recent days. "I think the main thing is — don't panic," he says. Tamara Keith/NPR hide caption

itoggle caption Tamara Keith/NPR

The National Debt Clock, a billboard-size digital display showing the increasing U.S. debt, is seen in New York City on Monday. Congress passed a bill Tuesday that would raise the nation's debt limit. Andrew Burton/Getty Images hide caption

itoggle caption Andrew Burton/Getty Images