Reading the numbers
Profitability and returns on capital
Margins tell you what the business keeps from a sale; returns on capital tell you what it earns on the money tied up in it. The second is the one that compounds.
Two different questions
Profitability metrics come in two families that beginners often merge, and the distinction is the whole point.
Margins ask: of every dollar of revenue, how much survives to this line? Gross margin survives the cost of the product. Operating margin also survives running the company. Free-cash-flow margin survives everything, including the capital spending the income statement politely defers.
Returns on capital ask something harder: for every dollar tied up in this business, how much does it earn in a year? A company can have gorgeous margins and a terrible return on capital, if earning those margins requires an enormous factory.
Only the second family tells you about compounding. A business earning 25% on its capital and able to reinvest at that rate doubles the capital's earning power roughly every three years. A business earning 6% does not, whatever its margins look like.
Why gross margin, of all things
It is the crudest line on the statement, and there is good evidence it is the most informative.
Novy-Marx's argument is that the further down the income statement you go, the more the number has been shaped by decisions that are not about the business's economics — research spending that will pay off later, acquisition accounting, tax structuring. Gross profit sits above nearly all of it. In his tests, gross profitability predicted returns about as well as book-to-market, and did it among the growth names where value screens are blind.
This is why our Profitability pillar carries it rather than starting at net income.
The metrics in detail
Return on Equity (ROE)
InvestopediaNet income ÷ Shareholders’ equity
Profit generated per dollar of shareholder capital. Buffett favors stable ROE above ~15% over many years — it signals pricing power and reinvestment discipline.
Example
Net income $3B, equity $20B → ROE = 15%.
If ROE jumps to 40% because equity was slashed via buybacks, check whether the business truly improved.
How to read it: Extremely high ROE from tiny equity bases can be fragile — pair with debt and cash-flow checks.
Return on Invested Capital (ROIC)
InvestopediaEBIT ÷ (Equity + Debt − Cash)
Return on all capital the business employs — closer to economic reality than ROE alone. Wide-moat companies often sustain double-digit ROIC.
Example
EBIT $2B, invested capital $16B → ROIC = 12.5%.
If WACC (cost of capital) is ~8%, ROIC > WACC suggests value-creating reinvestment.
How to read it: Pythia uses a 5-year average in the Profitability pillar to smooth cyclical spikes.
Gross profitability (GP/A)
Investopedia(Revenue − COGS) ÷ Total assets
Novy-Marx “other side of value”: efficient use of assets to produce gross profit, independent of leverage or tax strategy.
Example
Gross profit $6B, assets $30B → GP/A = 0.20.
Two firms with the same margin can differ if one needs far more assets to operate.
How to read it: Asset-heavy sectors (utilities, airlines) naturally show lower GP/A — compare within sector only.
Gross margin
Investopedia(Revenue − COGS) ÷ Revenue
What share of each sales dollar survives direct production costs. Rising gross margin often signals pricing power or mix shift to higher-margin products.
Example
Revenue $10B, COGS $4B → gross margin = 60%.
Software firms often run 70–80%+; grocery retailers might run 25%.
How to read it: Compare gross margin trend over 3–5 years, not a single quarter.
Net profit margin
InvestopediaNet income ÷ Revenue
Bottom-line efficiency after all expenses, taxes, and interest. Shows what ultimately lands as profit.
Example
Net income $1B on $10B revenue → 10% net margin.
A company can have strong gross margin but weak net margin if SG&A or interest is heavy.
How to read it: One-time tax benefits or write-downs distort a single year — use multi-year averages.
FCF margin (5y average)
InvestopediaFree cash flow ÷ Revenue (averaged over 5 years)
Cash actually left after running and investing in the business, relative to sales. Quality investors prefer durable double-digit FCF margins.
Example
FCF $2B, revenue $10B → 20% FCF margin.
If net income is high but FCF margin is negative, ask where the cash went (capex, working capital).
How to read it: Growth companies may reinvest heavily — low FCF margin today can be intentional if ROIC is high.
Where the denominator matters most
Return on equity is the one to be most careful with, because its denominator is equity — and equity shrinks when a company borrows to buy back stock.
A rising ROE can therefore mean the business got better, or it can mean the balance sheet got riskier, and the ratio alone cannot tell you which. That is exactly the ambiguity the DuPont decomposition exists to resolve, by splitting ROE into margin, asset turnover and leverage so you can see which one moved.
Return on invested capital sidesteps the problem by measuring against all the capital in the business, debt included. When the two disagree sharply, the gap is the leverage story.
Check yourself
4 questions. Nothing is recorded unless you are signed in, and nothing here affects anything else.
Sources
- Novy-Marx (2013), The Other Side of Value: The Gross Profitability Premium (opens in a new tab) — Gross profitability as the cleanest accounting measure of economic productivity.
- Investopedia — Return on invested capital (ROIC) (opens in a new tab)
- Investopedia — Gross margin (opens in a new tab)
Further reading
- Return on equity explained (opens in a new tab) — Quick ROE primer — pairs with our worked examples above.
- Research Before You Invest (opens in a new tab) — SEC — using public company data to judge fundamentals.
- Operating margin (opens in a new tab) — Operating income as a share of revenue.