To build a nest egg large enough to see you through retirement, which may last 30 years or more, you'll need the growth that stocks provide.
The stock market returned 9.8% a year on average between 1926 and 2009, versus just 5.4% for bonds, according to research firm Ibbotson Associates. Given stocks' superior returns over the long haul, most financial advisers recommend that investors whose retirement is more than 20 years away hold at least 3/4 of their portfolios in stocks and stock funds.
Of course, a stock-heavy portfolio can give you some hair-raising moments (or years). For example, during the 1973-74 bear market, U.S. stocks lost 43% of their value - and it took the market three-and-a-half years to recoup those losses. The stock market also suffered a 47.6% decline during the bear market at the start of this decade.
If you don't have the stomach for steep downturns, you might increase your allocation to include more bonds or bond funds. Holding, say, 70% of your portfolio in stocks and 30% in bonds will let you capture most of the long-term growth of stocks while sheltering your investments to a certain extent during market downturns.