Return on equity (ROE) is a closely watched number among knowledgeable investors. It is a strong measure of how well a company's management creates value for its shareholders. The number can be misleading, however, as it is vulnerable to measures that increase its value while also making the stock more risky. Without a way of breaking down ROE components, investors could be duped into believing a company is a good investment when it's not. Read on to learn how to use DuPont analysis to break apart ROE and get a much better understanding about where movements in ROE are coming from.
ROE: Simple, Perhaps too Simple
The beauty of ROE is that it is an important measure that only requires two numbers to compute: net income and shareholders' equity.
ROE = net income / shareholder's equity
If this number goes up, it is generally a great sign for the company as it is showing that the rate of return on the shareholders' equity is rising. The problem is that this number can also rise simply when the company takes on more debt, thereby decreasing shareholder equity. This would increase the company's leverage, which could be a good thing, but it will also make the stock more risky.
ThreeStep DuPont
To avoid mistaken assumptions, a more indepth knowledge of ROE is needed. In the 1920s the DuPont corporation created an analysis method that fills this need by breaking down ROE into a more complex equation. DuPont analysis shows the causes of shifts in the number.
There are two variants of DuPont analysis: the original threestep equation, and an extended fivestep equation. The threestep equation breaks up ROE into three very important components:
ROE = (net profit margin) * (asset turnover) * (equity multiplier) 
These components include:
 Operating efficiency  as measured by profit margin.
 Asset use efficiency  as measured by total asset turnover.
 Financial leverage  as measured by the equity multiplier.
The ThreeStep DuPont Calculation Taking the ROE equation: ROE = net income / shareholder's equity and multiplying the equation by (sales / sales), we get:
We now have ROE broken into two components: the first is net profit margin, and the second is the equity turnover ratio. Now by multiplying in (assets / assets), we end up with the threestep DuPont identity:
This equation for ROE breaks it into three widely used and studied components:

We have ROE broken down into net profit margin (how much profit the company gets out of its revenues), asset turnover (how effectively the company makes use of its assets) and equity multiplier (a measure of how much the company is leveraged). The usefulness should now be clearer.
If a company's ROE goes up due to an increase in the net profit margin or asset turnover, this is a very positive sign for the company. However, if the equity multiplier is the source of the rise, and the company was already appropriately leveraged, this is simply making things more risky. If the company is getting overleveraged, the stock might deserve more of a discount despite the rise in ROE. The company could be underleveraged as well. In this case it could be positive and show that the company is managing itself better.
Even if a company's ROE has remained unchanged, examination in this way can be very helpful. Suppose a company releases numbers and ROE is unchanged. Examination with DuPont analysis could show that both net profit margin and asset turnover decreased, two negative signs for the company, and the only reason ROE stayed the same was a large increase in leverage. No matter what the initial situation of the company, this would be a bad sign.
FiveStep DuPont
The fivestep, or extended, DuPont equation breaks down net profit margin further. From the threestep equation we saw that, in general, rises in the net profit margin, asset turnover and leverage will increase ROE. The fivestep equation shows that increases in leverage don't always indicate an increase in ROE.
The FiveStep Calculation Since the numerator of the net profit margin is net income, this can be made into earnings before taxes (EBT) by multiplying the threestep equation by 1 minus the company's tax rate:
We can break this down one more time, since earnings before taxes is simply earnings before interest and taxes (EBIT) minus the company's interest expense. So, if a substitution is made for the interest expense, we get:
The practicality of this breakdown is not as clear as the threestep, but this identity provides us with:

If the company has a high borrowing cost, its interest expenses on more debt could mute the positive effects of the leverage.
Learn the Cause Behind the Effect
Both the three and fivestep equations provide deeper understanding of a company's ROE by examining what is really changing in a company rather than looking at one simple ratio. As always with financial statement ratios, they should be examined against the company's history and its competitors.
For example, when looking at two peer companies, one may have a lower ROE. With the fivestep equation, you can see if this is lower because: creditors perceive the company as riskier and charge it higher interest, the company is poorly managed and has leverage that is too low, or the company has higher costs that decrease its operating profit margin. Identifying sources like these leads to better knowledge of the company and how it should be valued.
The Bottom Line
A simple calculation of ROE may be easy and tell quite a bit, but it does not provide the whole picture. If a company's ROE is lower than its peers, the three or fivestep identities can help show where the company is lagging. It can also shed light on how a company is lifting or propping up its ROE. DuPont analysis helps significantly broaden understanding of ROE.