Does Rio Tinto Pass Buffett's Test?

We'd all like to invest as successfully as the legendary Warren Buffett. He calculates return on invested capital to help determine whether a company has an economic moat -- the ability to earn returns on its money beyond that money's cost.

ROIC is perhaps the most important metric in value investing. By determining a company's ROIC, you can see how well it's using the cash you entrust to it, and whether it's actually creating value for you. Simply put, ROIC divides a company's operating profit by the amount of investment it took to get that profit:

ROIC = Net operating profit after taxes / Invested capital

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 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 lands between 8% and 12%. Ideally, we want to see ROIC greater than 12%, at minimum. We're also seeking a history of increasing returns, or at least steady returns, which indicate that the company's moat can withstand competitors' assaults.

Let's look at Rio Tinto (NYSE: RTP  ) and two of its industry peers to see how efficiently they use capital. Here are the ROIC figures for each company over several time periods:

Company	TTM	1 Year Ago	3 Years Ago	5 Years Ago
BHP Billiton (NYSE: BHP  )	18.2%	22.5%	31.7%	17.2%
Vale (NYSE: VALE  )	10.5%	12.0%	19.1%	26.4%
Rio Tinto	12.3%	10.6%	22.7%	7.6%

Source: Capital IQ, a division of Standard & Poor's. TTM = trailing 12 months.

BHP Billiton exceeds our 12% threshold for desirability in the last four quarters, but has come down from prior-period highs. Rio Tinto also has generated nice levels of ROIC, while after a steady series of declines, Vale's ROIC has dropped by more than half over five years. Despite some solid performances here, these companies are heavily reliant on commodity products whose prices fluctuate dramatically, suggesting that these ROIC figures are in large part driven by forces outside the companies' immediate control.

Businesses with consistently high ROIC are efficiently using capital. They can use their extra returns to buy back shares, further invest in their future success, or pay dividends to shareholders. (Warren Buffett especially likes that last part.)

To unearth more successful investments, dig a little deeper than the earnings headlines and check up on your companies' ROIC.

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