How do you read a real income statement over time?

A single year's income statement is a still frame from a movie. The insight is in the trend — how the lines move across several years. One column tells you almost nothing; five columns tell you a story.

Read across, not just down

The vertical read (revenue down to net income) shows the structure for one period. The horizontal read — the same line across years — shows momentum:

• Is revenue growing, flat, or shrinking? At what pace?
• Are margins expanding or compressing as the company grows? Rising revenue with falling margins means growth is getting more expensive.
• Is net income growing faster or slower than revenue? Faster usually means improving efficiency; slower means costs are outrunning sales.

Watch the relationship, not the absolute

A number in isolation ("$5B net income") means little. The relationships mean everything:

• Net income up 10% while revenue is up 5% → profits growing faster than sales (operating leverage at work).
• Revenue up 20% while net income is flat → the company is buying growth with margin. Not automatically bad, but a fact to understand.

Net income belongs to all the shares, so the figure most quoted is per share. Earnings per share divides net income attributable to common shareholders (after minority interest and preferred dividends) by the weighted average number of shares over the period. Two versions are reported. Basic uses the shares that exist. Diluted adds the shares that options, restricted stock and convertibles would create, and it is the lower figure. Diluted is what P/E, consensus estimates and screeners use, and it is the one to quote. One trap when you check it by hand: the "shares outstanding" figure on a company profile is a count on one date, not the weighted average over the year, so dividing net income by it gives a close but not identical EPS.

A rounded, illustrative trend

Suppose a company shows over three years (illustrative): revenue $40B → $46B → $50B, and net income $4B → $4.2B → $5B. Revenue grew about 25% over the span; net income grew about 25% too. Profit kept pace with sales — the business scaled without losing efficiency. Change the final year's net income to $3.5B and the story flips to "growth without profit follow-through" — same top line, different meaning. You're describing the pattern, not forecasting the next year.

Beware seasonality

Many businesses earn wildly different amounts by quarter — a retailer books much of its profit in the holiday quarter. Comparing Q4 to Q1 can mislead. The fix: compare a quarter to the same quarter last year (year-over-year), or use full-year figures.

In the data

Financial years are labelled by the day they end, not by the calendar. Apple's year ends in September; Walmart's ends at the close of January. Here is Walmart's fiscal calendar, with the day its latest year closed and the day those figures were filed:

So lining one company's "2025" up against another's can silently compare two different twelve-month windows. And the filing date is not the period end: Apple's year to September 2025 was not public until its filing at the end of October. That gap is the difference between what was true of a period and what anyone could know during it.

Try it now

Two published growth figures, which are a start and a warning at the same time:

1. Read the quarterly revenue growth row. Notice what it actually measures: one quarter against the same quarter a year earlier. A single strong quarter can put it far above anything an annual series supports, so it is not the multi-year rate this lesson asks for.
2. Now the real horizontal read. The annual series is keyed by period-end date; here are its six newest years:

Compute revenue growth and net income growth from the oldest year in the table to the newest. Which grew faster? 3. Track net margin (net income ÷ total revenue) across those same years — trending up, down, or flat? Write one neutral sentence describing the trajectory. 4. Before you compare that trajectory to another company, read the fiscal year end for both. Apple's:

Set it beside Walmart's, in the fiscal-calendar table under "In the data" above. Count the months of overlap between the two companies' latest fiscal years. Anything less than twelve and the comparison you were about to make is between two different years wearing the same label.

Unit done. Next, the statement most free courses skip — and the one professionals trust most.