It's bad enough that you have to take market risk. Only a fool takes on the additional risk of doing yet more damage by failing to diversify properly with his or her nest egg. Avoid the problem-buy a well-run index fund and own the whole market.

An index fund is a fund that simply invests in all of the stocks in a market. So, for example, an index fund might invest in every single stock or almost every single stock in the U.S. market, it might invest in every single stock abroad, or it might invest in all of the bonds that are out there. And you can make a perfectly fine investing portfolio that mixes equal parts of all three of those.

While it is probably a poor idea to own actively managed funds in general, it is truly a terrible idea to own them in taxable accounts... taxes are a drag on performance of up to 4 percentage points each year... many index funds allow your capital gains to grow largely undisturbed until you sell... For the taxable investor, indexing means never having to say you're sorry.

The typical fund company services 401k plan participants in the same way that Baby Face Nelson serviced banks.

Mutual fund manager performance does not persist and the return of stock picking is zero.

When it comes to fund managers and market strategists, this year's hero usually turns into next year's zero.

A decade ago, I really did believe that the average investor could do it himself. I was wrong. I've come to the sad conclusion that only a tiny minority, at most one percent, are capable of pulling it off. Heck, if Helen Young Hayes, Robert Sanborn, Julian Robertson, and the nation's largest pension funds can't get it right, what chance does John Q. Investor have?