Investors have a natural attraction to large-cap stocks, and that's understandable. Everyone's heard of Cisco Systems and Coca-Cola, after all, and most know what they do to generate revenue. There's also a lot of analyst and news coverage for large caps, so we all have a good way of knowing what these firms are up to. Sounds like a great deal, right?

Well, it is -- if you want to settle for lower returns.

Why you need small caps
According to research from NYU professor Aswath Damodaran, studies have consistently found that smaller companies "earn higher returns than larger firms of equivalent risk." During Damodaran's study period of 1927 to 2001, the smallest companies outperformed the largest ones with a 20% annual return versus 12% on a value-weighted basis. The outperformance was even greater on an equally weighted basis.

One reason is that small caps, being, um ... small, simply have more "room to run" than the big boys. You can get a better sense of this by looking at some of the top-performing large- and small-cap stocks over the past five years. First, some of the best companies with a market cap of more than $40 billion five years ago:

Company

March 2003 Market Cap
(in Billions)

Total Five-Year Return

Chevron

$69

169%

ExxonMobil

$231

153%

Toyota

$86

95%

Procter & Gamble (NYSE: PG)

$105

64%

Abbott Labs (NYSE: ABT)

$55

53%

Now, here were just some of the better performers for companies with a market cap between roughly $200 million and $2.5 billion (the universe we search to make recommendations for our Motley Fool Hidden Gems small-cap investing service):

Company

March 2003 Market Cap (in Millions)

Total Five-Year Return

Research In Motion

$930

5,060%

MEMC Electronic Materials (NYSE: WFR)

$1,762

747%

Celgene (Nasdaq: CELG)

$1,765

906%

Terex (NYSE: TEX)

$560

1,042%

Manitowoc (NYSE: MTW)  

$483

791%

U.S. Steel (NYSE: X)

$1,201

827%

*Data provided by Capital IQ, a division of Standard & Poor's.

Simply put, the smallest companies have much more upside than the largest. But be aware: Higher potential reward comes with higher risk. Buy one of the worst-performing small caps, and you'll likely earn a total loss of capital -- which is a fancy Wall Street phrase for "losing all your money." That's why at Hidden Gems, we seek out only the highest-quality small caps: those with high insider ownership, a strong balance sheet, a solid business model, and compelling valuation.

It's time to think small
Using these principles, the team's stock recommendations have outperformed the S&P 500 by an average of 30% to 8% since the service began more than four years ago. This shows that small caps can indeed improve returns and should be a part of any balanced portfolio.

If you're interested in a look at all of the Hidden Gems recommendations, we offer a full-access, 30-day free trial to the service. Here's more information.

This article was originally published on Sept. 14, 2006. It has been updated.

Rex Moore has nearly mastered quantum mechanics but is stuck on that "wave-particle duality" thingie. He owns no shares of companies mentioned in this story. Coca-Cola is an Inside Value pick. The Fool's disclosure policy shines year-round.