[traviswebb]

re stock market: A common (and expensive) fallacy of beginners who think they can beat the market with clever technical tricks is analyzing all of the publicly-traded companies' history and divining patterns in trading and such. This ignores, of course, the countless companies that have gone out of business completely or have otherwise been de-listed from the exchanges.

In analyzing these trends, you're biased by looking only at the companies that have done well enough to be on the current list. In this way it's particularly insidious, because you're omitting the very data that might save you from betting on a company that might be delisted.