Investing isn't easy. Even Warren Buffett counsels that most investors should invest in a low-cost index like the S&P 500. That way, "you'll be buying into a wonderful industry, which in effect is all of American industry," he says.

But there are, of course, companies whose long-term fortunes differ substantially from the index. In this series, we look at how individual stocks have performed against the broad S&P 500.

Step on up, Molson Coors (NYSE:TAP).

Molson Coors shares have slightly underperformed the S&P 500 over the past quarter-century:

Source: S&P Capital IQ.

Since 1987, shares have returned an average of 7.8% a year, compared with 9.7% a year for the S&P (both include dividends). One thousand dollars invested in the S&P in 1987 would be worth $19,200 today. In Molson Coors, it'd be worth $10,900.

Dividends accounted for a lot of those gains. Compounded since 1987, dividends have made up 57% of Molson Coors' total returns. For the S&P, dividends account for 39% of total returns.

Now have a look at how Molson Coors earnings compare with S&P 500 earnings:

Source: S&P Capital IQ.

Pretty good outperformance here. Since 1995, Molson Coors' earnings per share have increased by an average of 11.4% a year, compared with 6% a year for the broader index.

What's that meant for valuations? Molson Coors has traded for an average of 19 times earnings since 1987 -- below the 24 times earnings for the broader S&P 500.

Through it all, shares have been relative disappointments over the past quarter-century.

Of course, the important question is whether that will continue. That's where you come in. Our CAPS community currently ranks Molson Coors with a five-star rating (out of five). Care to disagree? Leave your thoughts in the comment section below, or add Molson Coors to My Watchlist.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.