TIME TO RETIRE 60/40?: Many experts question whether an investment portfolio with 60 percent in stocks and 40 percent in bonds is a good starting point for many investors.

60/40 BACKGROUND: The 60/40 portfolio is considered a rough gauge for how to build adequate retirement savings without taking excessive risk. It's promoted for investors a decade or two from retirement.

CHIEF CRITICISMS: Critics say a 60/40 approach relies too much on bonds. The long-term outlook for bonds is poor because yields are near all-time lows. Others say a diversified portfolio should include alternative assets, and not just stocks and bonds.