If owning stocks is a long-term project for you, following their changes constantly is a very, very bad idea. It's the worst possible thing you can do, because people are so sensitive to short-term losses. If you count your money every day, you'll be miserable.

We are often confident even when we are wrong, and an objective observer is more likely to detect our errors than we are.

People tend to assess the relative importance of issues by the ease with which they are retrieved from memory—and this is largely determined by the extent of coverage in the media. Frequently mentioned topics populate the mind even as others slip away from awareness. In turn, what the media choose to report corresponds to their view of what is currently on the public’s mind. It is no accident that authoritarian regimes exert substantial pressure on independent media. Because public interest is most easily aroused by dramatic events and by celebrities, media feeding frenzies are common

Finally, the illusions of validity and skill are supported by a powerful professional culture. We know that people can maintain an unshakeable faith in any proposition, however absurd, when they are sustained by a community of like-minded believers. Given the professional culture of the financial community, it is not surprising that large numbers of individuals in that world believe themselves to be among the chosen few who can do what they believe others cannot.

We deeply want to be led by people who know what they're doing and who don't have to think about it too much.

Hindsight bias makes surprises vanish.

An executive might have a very strong intuition that a given product has promise, without considering the probability that a rival is already ahead in developing the same product.