WSJ: What Is 'Alpha' in Investing?

By SIMON CONSTABLE

When you pick portfolio managers, you need to know how good they are at their job—or put another way, how much alpha they add.

If you could have done just as well buying an index-tracking investment—such as the SPDR S&P 500 exchange-traded fund for broad U.S.-stock exposure—your portfolio manager isn't adding any alpha. If the manager does better than just tracking the market benchmark, then he or she is adding alpha.Alpha, the first letter of the Greek alphabet, in this context means the positive difference someone makes in the investment process, says Art Hogan, chief investment strategist at Lazard Capital Markets in Boston. An investment manager who adds a lot of alpha is "a good stock picker or sector picker," he says.

Alpha only goes so far, though. "When you add alpha it's a relative term," says Mr. Hogan. For instance, if you owned gold stocks and the gold sector plummeted like it did recently, your alpha might be that you lost less money than other investors.

Also, don't confuse alpha with beta, another term taken from the Greek alphabet. In this conversation, beta refers to how stocks move relative to the overall market. A stock with a beta of 1 moves in sync with the market.

See original story here.