I Screen, You Scream: The Perils of Stock-Screening Tools

You'll find stock screens on just about every major financial Web site you visit, and most of them are free. If you're a seasoned investor, they're among the most useful tools available online.

But common as they are, stock screens come with very little training on how to use them. This makes them among the most dangerous tools available on the Web. Used incorrectly, a stock screen can loose you a fortune in bad trades.

Stock screens are online search engines that help you find the kinds of stocks you'd like to trade. There are also screens that help you select mutual funds. But we'll just be dealing with stock screens here. (A shortlist of some of my favorites appears at the end of this column.) ...