Now Playing: 6-26-13 Marketplace Morning Report: Obama goes to Africa

President Obama is on his way to Africa for a week-long trip that will take him to Senegal, South Africa and Tanzania. The visit is, in part, aimed at increasing U.S. trade and investment on the continent. China's markets are down as the country's central bank cracks down on 'shadow banking' by tightening credit. And 401(k), 403(b) -- which retirement plan is the best for you?