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Revenue grew. Why might profit fall?

A worked example of revenue growth and operating margin, with a separate check for cash flow.

Two things to take away
  • Read revenue growth alongside operating margin.
  • A changed ratio does not establish its cause.

Revenue growth alone is an incomplete account of performance. A larger sales base can coexist with lower profit. FirmLens places revenue, net income and operating income together, but those figures do not reveal cash movements or the cause of a change.

A worked example

This is a fictional business, not a real company’s results. Assume both years use the same currency, annual period and consolidated scope. All amounts below are in millions.

MeasurePrior yearCurrent year
Revenue100120
Operating income109
Operating margin10.0%7.5%

Revenue grew by (120 − 100) / 100 = 20%. Operating income changed by (9 − 10) / 10 = −10%. The new margin is 9 / 120 = 7.5%, a decline of 2.5 percentage points. A percentage-point change is different from a percentage change.

What the calculation cannot tell you

The example establishes that operating income is a smaller share of revenue. It does not establish whether costs, a one-time charge, expansion spending or another change caused it. Read the expense details and notes before assigning a cause. A plausible explanation is still only a hypothesis.

Check earnings and cash separately

Net income and operating income are different measures. Profit recognition and cash movements can also occur at different times. Use the cash flow statement to investigate cash movements. The SEC’s financial-statement guide explains the roles of the statements. Cash flow is not currently included in FirmLens summary cards; follow the annual filing link.

Check the denominator and missing values

A prior revenue of zero does not support the same growth formula. Missing values should never be replaced with zero to force a comparison. FirmLens leaves growth unavailable when the comparable prior annual revenue is absent or nonpositive. For a move between profit and loss, reading the amounts and direction is clearer than relying on a single percentage.

This exercise explains arithmetic and interpretation. It does not value a security or predict future investment returns.

Try it in an original filing

These links are starting points for reading practice. Open an annual source document from a company profile and apply the checks in this guide.

LG Electronics 066570 ↗Costco Wholesale COST ↗

Official references

Use these primary sources to check concepts and filing structure. Worked examples are fictional scenarios created for FirmLens.

References checked: 2026-09-16


This educational guide uses official references and AI writing assistance. It is not individualized advice from a financial professional. Examples are separate from source facts. Report errors through our corrections page.

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