Speculators are obsessed with predicting: guessing the direction of stock prices. Every morning on cable television, every afternoon on the stock market report, every weekend in Barron's, every week in dozens of market newsletters, and whenever business people get together. In reality, no one knows what the market will do; trying to predict it is a waste of time, and investing based upon that prediction is a purely speculative undertaking.

Always remembering that we might be wrong, we must contemplate alternatives, concoct hedges, and search vigilantly for validation of our assessments. We always sell when a security's price begins to reflect full value, because we are never sure that our thesis will be precisely correct.

When a government official says a problem has been "contained," pay no attention.

A simple rule applies: if you don't quickly comprehend what a company is doing, then management probably doesn't either.

In the financial markets, however, the connection between a marketable security and the underlying business is not as clear-cut. For investors in a marketable security the gain or loss associated with the various outcomes is not totally inherent in the underlying business; it also depends on the price paid, which is established by the marketplace. The view that risk is dependent on both the nature of investments and on their market price is very different from that described by beta.

The inability to hold cash and the pressure to be fully invested at all times meant that when the plug was pulled out of the tub, all boats dropped as the water rushed down the drain.

Avoid organizing investment team into silos.