Though stock market volatility continues to rattle investors' nerves, the future looks bright for equities in the U.S. and many emerging markets, according to Wharton finance professor Jeremy Siegel. That's not so for bonds, which could become money-losing investments as rising interest rates drive bond prices down. In an interview with Knowledge@Wharton, Siegel says that investors should think about reducing their bond holdings, buying more stocks and keeping just enough cash for a rainy day and other liquidity needs, since interest rates on cash are near zero. With the housing market -- so critical to the U.S. economy -- clearly improving, anyone who has held off buying a home should think about buying now while prices and mortgage rates are low, Siegel adds.