American Century offers a variety of dedicated stock, bond, and money market funds, as well as funds that blend various asset classes. The so-called Asset Allocation mutual funds include target-risk funds, which automatically rebalance to meet your current level of risk (ranging from "very conservative" to "very aggressive"), and target-date funds that are based on the length of time you plan on holding the fund (the plans automatically shift from more aggressive investments initially to more conservative choices as the target date nears).