We used to have the same Fidelity funds in our 401k that were available directly from Fidelity. I had always compared the NAVs and performance and found them to be exactly the same, so I was comfortable relying on the expense ratios published in the fund's prospectus. Now megacorp has switched to a selection of private funds (still managed by Fido) and I don't believe the expense ratios are published. I suspect the cost to run these is cheaper and Megacorp/Fido are pocketing the difference, but for all I know, I could be paying more in fees. Another reason to go with index funds.