We'd all like to invest like the legendary Warren Buffett, turning thousands into millions or more. Buffett analyzes companies by calculating return on invested capital, or ROIC, in order to help determine whether a company has an economic moat -- the ability to earn returns on its money above that money's cost.

In this series, we examine several companies in a single industry to determine their ROIC. Let's take a look at ExxonMobil (NYSE: XOM) and three of its industry peers, to see how efficiently they use cash.

Of course, it's not the only metric in value investing, but ROIC may be the most important one. By determining a company's ROIC, you can see how well it's using the cash you entrust to it and whether it's creating value for you. Simply put, it divides a company's operating profit by how much investment it took to get that profit. The formula is:

ROIC = net operating profit after taxes / Invested capital

(You can get further details on the nuances of the formula.)

This one-size-fits-all calculation cuts out many of the legal accounting tricks (such as excessive debt) that managers use to boost earnings numbers, and it provides you with an apples-to-apples way to evaluate businesses, even across industries. The higher the ROIC, the more efficiently the company uses capital.

Ultimately, we're looking for companies that can invest their money at rates that are higher than the cost of capital, which for most businesses is between 8% and 12%. Ideally, we want to see ROIC above 12%, at a minimum, and a history of increasing returns, or at least steady returns, which indicate some durability to the company's economic moat.

Here are the ROIC figures for Exxon and three industry peers over a few periods.

Company

TTM

1 Year Ago

3 Years Ago

5 Years Ago

ExxonMobil 13% 8.9% 28.2% 26.2%
Chevron (NYSE: CVX) 14.3% 10% 17.2% 17.1%
ConocoPhillips (NYSE: COP) 9.5% 8.4% 12.4% 10.2%
BP (NYSE: BP) 9.5% (5%)* 14.8% 12.7%

Source: S&P Capital IQ. TTM=trailing 12 months.
*Because BP did not report an effective tax rate, we used its 35% rate from three years ago.

ExxonMobil's returns on invested capital are less than half of what they were five years ago. The other companies have also seen declines, albeit less dramatic, over the same time period, which suggests that the oil industry is facing difficult times right now.

The huge swings you see in the returns at Exxon and its competitors are probably related to fluctuating oil prices, which cause volatility in the companies' sales figures. The value of these companies may also be affected by their exposure to new cleaner-energy alternatives.

Although Exxon has a solid track record of high ROIC, its yield is not the highest among these peers. Exxon's 2.3% dividend yield is much lower than Chevron's 3.2%, ConocoPhillips' 3.7%, and BP's 3.9%, suggesting that investors have bid up shares of this consistently reliable performer.

Businesses with consistently high ROIC show that they're efficiently using capital. They also have the ability to treat shareholders well, because they can then use their extra cash to pay out dividends to us, buy back shares, or further invest in their franchise. And healthy and growing dividends are something that Warren Buffett has long loved.

So for more successful investments, dig a little deeper than the earnings headlines to find the company's ROIC. Feel free to add these companies to your Watchlist: