Based on an AARP survey, 70% people don't know they are paying fees in their 401(k) investment, despite NerdWallet.com finds that there are at least 28 types of fees related 401(k) accounts, such as management and administration fees, trading costs, record keeping fees, etc.
How do you get smart on 401(k) fees? Before you investing in a fund, go to Morningstar.com and check the fund's expense ratios and compare the expense ratios to the average figures for that asset class.