One of the best investments we can make is in our own knowledge and skill set. With that in mind, this article will work through how we can use Return On Equity (ROE) to better understand a business. We'll use ROE to examine MTR Corporation Limited (HKG:66), by way of a worked example.

MTR has a ROE of 8.1%, based on the last twelve months. Another way to think of that is that for every HK$1 worth of equity in the company, it was able to earn HK$0.08.

See our latest analysis for MTR

How Do You Calculate Return On Equity?

The formula for ROE is:

Return on Equity = Net Profit ÷ Shareholders' Equity

Or for MTR:

8.1% = HK$14b ÷ HK$181b (Based on the trailing twelve months to June 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 the money paid into the company from shareholders, plus any earnings retained. You can calculate shareholders' equity by subtracting the company's total liabilities from its total assets.

What Does Return On Equity Mean?

ROE measures a company's profitability against the profit it retains, and any outside investments. The 'return' is the yearly profit. A higher profit will lead to a higher ROE. So, all else equal, investors should like a high ROE. That means it can be interesting to compare the ROE of different companies.

Does MTR 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. However, this method is only useful as a rough check, because companies do differ quite a bit within the same industry classification. If you look at the image below, you can see MTR has a similar ROE to the average in the Transportation industry classification (6.9%).

That's not overly surprising. 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. If you are like me, then you will not want to miss this free list of growing companies that insiders are buying.

The Importance Of Debt To Return On Equity

Most companies need money -- from somewhere -- to grow their profits. That cash can come from issuing shares, retained earnings, or debt. In the first two cases, the ROE will capture this use of capital to grow. In the latter case, the debt used for growth will improve returns, but won't affect the total equity. Thus the use of debt can improve ROE, albeit along with extra risk in the case of stormy weather, metaphorically speaking.

Combining MTR's Debt And Its 8.1% Return On Equity

MTR has a debt to equity ratio of 0.20, which is far from excessive. Its ROE isn't particularly impressive, but the debt levels are quite modest, so the business probably has some real potential. Judicious use of debt to improve returns can certainly be a good thing, although it does elevate risk slightly and reduce future optionality.