Investing in Your 401(k) is not free, but because you don't get a bill showing how many fees are withdrawn every quarter (or every year), many don't know they're paying or how much they're paying to invest in their Company's Plan.
And if you don't know, you should work to find out. Admittedly, I don't know exactly how much I pay but I have an idea. If your company allows you to see your 401(k) information online, chances are all you see is fund performance. You don't know that you're paying fees. Our company offers about 12 different funds, and I have 4 major funds in my account. Two are with Vanguard, one with Neuberger and one with American Century. I really had to dig to find out the fees associated with each, because they're not really all that apparent.
These management fees can eat into your returns if you're not careful. Consider the example below:
Fund A:
1-yr return: 5%
5-yr return: 10%
10-yr return: 11%
Management Fee: 2.0%
Fund B:
1-yr return: -5%
5-yr return: 13%
10-yr return: 10%
Management Fee: 0.35%
Fund C:
1-yr return: 33%
5-yr return: 13%
10-yr return: 7%
Management Fee: 0.75%
Think of the management fee as the "cost" of managing your money. Which fund would you choose if you were finding a place to put your money for a long time (5+ years)? Smart money would be in (B) of course. Some investors love to see those high returns in the 1-yr numbers, but it's unproven. Long term returns are what count. Note that although choice (A) may have a higher return, the management fee is deducted from the returns. Also note that your returns should be at or above the S&P 500 long-term average. One more thing: that fee is deducted from your account yearly regardless whether you make money or lose money.
So, if your 401(k) is accessible online with your employer, you should try to get access to the prospectus, which gives all the details on the fund you own. (Or, go to the fund's website) and download it from there. Inside you should look for the management fee section, which will give upfront cost (usually) of owning that fund. Some of the older funds may charge fees as high as 2-3% of your account balance, while others (like Vanguard) charge very low management fees.