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.

You have to understand what market history looks like. What market history tells you is that the very, very best investments are made when things look the worst.

It's human nature to find patterns where there are none and to find skill where luck is a more likely explanation (particularly if you're the lucky manager).

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.

You have to understand your own psychology. You have to understand that human beings weren't really designed to invest. We have all these emotions that are appropriate responses if you're being chased by a tiger, but they're terrible responses if you've got a 30-year time horizon to think about investment or when you're trying to manage investment over 30 years.

The reason that 'guru' is such a popular word is because 'charlatan' is so hard to spell.