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, Edison International (NYSE:EIX).

Edison International shares have slightly underperformed the S&P 500 over the last quarter-century:

Eix Sp

Source: S&P Capital IQ.

Since 1987, shares have returned an average of 8.5% 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 Edison International, it'd be worth $13,600.

Dividends accounted for a lot of those gains. Compounded since 1987, dividends have made up about 75% of Edison International's total returns. For the S&P, dividends account for 39% of total returns.

Now have a look at how Edison International earnings compare with S&P 500 earnings:

Eix Earnings

Source: S&P Capital IQ.

Some underperformance here, too. Since 1995, Edison International's earnings per share have increased by an average of 3% a year, compared with 6% a year for the broader index.

What's that meant for valuations? Edison International has traded for an average of 13 times earnings since 1987 -- below the 24 times earnings for the broader S&P 500.

Through it all, shares have been slight disappointments over the last quarter-century.

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

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