Generally, that will include funds that invest in stocks of large and smaller U.S. companies, international stocks, bonds and various cash investments such as money market or stable value funds. Each has a different investment style. The funds you choose, and the amount you invest in each choice, are major decisions that deserve time and attention. Stocks of large and small U.S. companies tend to go up and down at different rates at different times. And international stocks usually act differently than U.S. stocks.
Bonds march to their own drummer.
And cash accounts are very stable, giving a safe but modest return. Spreading your investments across several different categories helps to reduce volatility. The mix you choose is your investment throttle . A very conservative mix, or a light touch on the throttle, would consist mostly of bonds and cash investments. An aggressive portfolio tends to be more volatile, going up and down more radically, but is also likely to give a bigger return over many years.