Profit margins explained

A margin measures how much of each dollar of revenue is left after a category of costs. Gross margin is revenue minus cost of goods sold, divided by revenue. Operating margin then subtracts operating expenses such as salaries, rent, and research. Net margin subtracts everything that remains, including interest and taxes, and is the bottom-line figure.

Reading all three together shows where profit is made or lost. A company can have a healthy gross margin but a thin net margin if operating costs, interest, or one-time charges are heavy.

Margins are calculated from the income statement in a company’s 10-K and 10-Q filings, so they are reported quarterly and typically appear weeks after the period ends. Aerarium Research builds them from those reported figures and keeps the source period visible.

Margins vary enormously by business model — a grocery chain may run a low single-digit net margin while a software company runs far higher. Comparing margins across unlike industries, or across companies using different accounting policies, is rarely meaningful.

A high margin is not the same as a healthy or growing business, and it does not predict stock returns. A shrinking company can still post high margins, and a one-time tax benefit can flatter net margin for a single period.

Read margins as a trend across several periods alongside revenue and segment context, and check the filing footnotes for one-time items. Margins are factual context, not a verdict on value.