This article By Henry Blodget at Slate:
The most dangerous investment advice is often that which seems most sensible, which is why the worst investing counsel you will likely ever receive is that you should try to pick "good" stocks and sell "bad" ones. You will get this advice in one form or another from innumerable sources, including (some) investment advisers, friends, colleagues, Wall Street, and the investment media. You should ignore it....
...Most stock pickers believe that they are among the tiny minority of investors who can beat the market after costs, and, for inspiration and encouragement, they point to legends such as Warren Buffett and Benjamin Graham. What such investors often don't know is that even Buffett has said that the best strategy for most investors is to buy low-cost index funds and that the great Benjamin Graham eventually changed his mind about the wisdom of traditional stock-picking...
...The stock-picking mystique is so deeply entrenched in our financial culture that it feels like heresy to suggest that it is, on balance, dumb. The facts are clear, however. For the vast majority of investors—including professionals—stock-picking efforts waste both money and time...
