Stock Doc: Stocks, Emotions Don't Mix

Editor's note: Alden Cass, a psychologist, writes two columns for TheStreet.com: one that delves into how behavior and emotions affect investing, the other a health column specifically for men.

One of my favorite movies of all time is Wall Street, in which Michael Douglas portrays Gordon Gekko, a cut-throat arbitrage tycoon. In one scene, Gekko tells Bud Fox (played by Charlie Sheen) to never get emotional about stocks because it clouds judgment.

When it comes to making a trade or an investment, many individuals fall into this trap and remain unaware of it until they have lost too much money to recover.

This reminds me of a past client of mine, whom, to protect his identity, we'll call "Matt." He had been a big fan of drug company Pfizer(PFE Quote). His now-deceased father had given him Pfizer shares, which he'd purchased at $11 in 1996, prior to the stock's renaissance years. Matt loved this stock, and he made tremendous returns from it. ...