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Many investors are still learning about the various metrics that can be useful when analysing a stock. This article is for those who would like to learn about Return On Equity (ROE). We'll use ROE to examine Advance Auto Parts, Inc. (NYSE:AAP), by way of a worked example.

Our data shows Advance Auto Parts has a return on equity of 12% for the last year. One way to conceptualize this, is that for each $1 of shareholders' equity it has, the company made $0.12 in profit.

Check out our latest analysis for Advance Auto Parts

How Do I Calculate ROE?

The formula for ROE is:

Return on Equity = Net Profit ÷ Shareholders' Equity

Or for Advance Auto Parts:

12% = US$430m ÷ US$3.5b (Based on the trailing twelve months to April 2019.)

Most know that net profit is the total earnings after all expenses, but the concept of shareholders' equity is a little more complicated. It is all earnings retained by the company, plus any capital paid in by shareholders. The easiest way to calculate shareholders' equity is to subtract the company's total liabilities from the total assets.

What Does ROE Signify?

ROE measures a company's profitability against the profit it retains, and any outside investments. The 'return' is the amount earned after tax over the last twelve months. The higher the ROE, the more profit the company is making. So, as a general rule, a high ROE is a good thing. Clearly, then, one can use ROE to compare different companies.

Does Advance Auto Parts Have A Good ROE?

One simple way to determine if a company has a good return on equity is to compare it to the average for its industry. The limitation of this approach is that some companies are quite different from others, even within the same industry classification. You can see in the graphic below that Advance Auto Parts has an ROE that is fairly close to the average for the Specialty Retail industry (13%).

That's neither particularly good, nor bad. ROE tells us about the quality of the business, but it does not give us much of an idea if the share price is cheap. I will like Advance Auto Parts better if I see some big insider buys. While we wait, check out this free list of growing companies with considerable, recent, insider buying.

How Does Debt Impact Return On Equity?

Virtually all companies need money to invest in the business, to grow profits. That cash can come from issuing shares, retained earnings, or debt. In the case of the first and second options, the ROE will reflect this use of cash, for growth. In the latter case, the use of debt will improve the returns, but will not change the equity. Thus the use of debt can improve ROE, albeit along with extra risk in the case of stormy weather, metaphorically speaking.

Advance Auto Parts's Debt And Its 12% ROE

Although Advance Auto Parts does use debt, its debt to equity ratio of 0.21 is still low. The combination of modest debt and a very respectable ROE suggests this is a business worth watching. Careful use of debt to boost returns is often very good for shareholders. However, it could reduce the company's ability to take advantage of future opportunities.

But It's Just One Metric

Return on equity is one way we can compare the business quality of different companies. Companies that can achieve high returns on equity without too much debt are generally of good quality. If two companies have the same ROE, then I would generally prefer the one with less debt.

Having said that, while ROE is a useful indicator of business quality, you'll have to look at a whole range of factors to determine the right price to buy a stock. The rate at which profits are likely to grow, relative to the expectations of profit growth reflected in the current price, must be considered, too. So you might want to check this FREE visualization of analyst forecasts for the company.

Of course Advance Auto Parts may not be the best stock to buy. So you may wish to see this free collection of other companies that have high ROE and low debt.

We aim to bring you long-term focused research analysis driven by fundamental data. Note that our analysis may not factor in the latest price-sensitive company announcements or qualitative material.

If you spot an error that warrants correction, please contact the editor at editorial-team@simplywallst.com. This article by Simply Wall St is general in nature. It does not constitute a recommendation to buy or sell any stock, and does not take account of your objectives, or your financial situation. Simply Wall St has no position in the stocks mentioned. Thank you for reading.