How Your 401(k) Plan Is Costing You Money

A 401(k) plan has lots of fees, and savvy investors may be aware of various investment-related charges – such as a management fee to a mutual fund manager's or the sales commission paid when making a transaction.

What most people don't know, however, is that 401(k) plans also include several other hidden fees that can eat away at their investments.

These include so-called "12b-1 fees" (which are marketing fees passed along to investors) and administrative costs of various types imposed by retirement plan sponsors.

Finding these fees isn't easy. In fact, you have to pore over a fund's prospectus and an annual report to ferret out exactly what charges are imposed by a 401(k) retirement plan.