401(k)s can contain many types of assets, depending on the provider. For example, mine has stock-only indexes, bond indexes, mixed funds (stocks and bonds) but

401(k)s can contain many types of assets, depending on the provider. For example, mine has stock-only indexes, bond indexes, mixed funds (stocks and bonds) but ALSO it has fixed income funds, which return ~4.8% pa. That's not going to make you salivate, but it's not a bad place to be if you believe the market is over priced. 401(k)s can (and should) be invested across a portfolio of different asset classes (and geos) according to your retirement needs. Asset allocations should be changed over time as retirement nears. this is my personal opinion, not financial advice :)