LIKE ROE and ROA, calculating a company's margins is a way of getting at management efficiency. But instead of measuring how much managers earn from assets or capital employed, this ratio measures how much a company squeezes from its total revenue (sales).
Sounds a lot like earnings, right? Well, margins are really just earnings expressed as a ratio -- a percentage of sales. The advantage is that a percentage can be used to compare the profitability of different companies while an absolute number cannot. An example should help. In the spring of 1999, Sears had net income of about $1.1 billion on annual sales of about $41.2 billion. Wal-Mart, meanwhile, was earning about $4.7 billion on sales of $143 billion. Comparing $4.7 billion with $1.1 billion wouldn't tell you much about which company was more efficient. But if you divide the earnings by the sales, you'll see that Wal-Mart was returning 3.3% on sales while Sears was returning just 2.7%. The difference doesn't sound like much but it was worth about $839 million to Wal-Mart shareholders. And it's one of the reasons Wal-Mart was trading at about twice the multiple of Sears.
Analysts look at various types of margins -- gross, operating, pretax or net. Each uses an earnings number that is further down the Income Statement (see Price/Cash Flow for more on how the Income Statement works). What's the difference? As you move down the statement, different types of expenses are factored in. The various margin calculations let you refine what you're looking at.
Margins are particularly helpful since they can be used both to compare profitability among many companies (as we demonstrated with Wal-Mart and Sears above) and to look for financial trouble at a single outfit. Viewing how a company's margins grow or shrink over time can tell you a lot about how its fortunes are changing. Between early 1995 and January of 1999, for instance, Dell Computer's net margin doubled from 4.3% to 8% even as the cost of a PC declined markedly. What does that tell you? Dell was driving down prices and manufacturing more efficiently. Rival Compaq Computer, meanwhile, went disastrously in the opposite direction -- 8% to -8% -- as the company ran into trouble digesting several acquisitions and began to lose money. That helps explain why Compaq's shares rose about 250% during that time while Dell's roared ahead almost 8,000%.