Revenue, costs, margins, and earnings — how to tell if a company actually makes money.
Every public company files three financial statements every quarter:
You'll learn all three. Start here.
Read the income statement top to bottom. Each line subtracts something from the line above:
Revenue $100
- Cost of Goods Sold (COGS) -$40
─────────────────────────────────
Gross Profit $60
- Operating Expenses -$30 (R&D, marketing, salaries)
─────────────────────────────────
Operating Income $30
- Interest & Taxes -$10
─────────────────────────────────
Net Income $20
In one glance: this company turns every $100 of sales into $20 of profit. That's a 20% net margin — quite strong.
Margins compare profit to revenue at each stage. Higher = more efficient.
| Margin | Formula | What It Tells You |
|---|---|---|
| Gross Margin | Gross Profit / Revenue | How profitable each sale is before overhead |
| Operating Margin | Operating Income / Revenue | Profitability of the core business |
| Net Margin | Net Income / Revenue | What's left for shareholders |
Software companies often have 70%+ gross margins. Grocery stores might have 25%. Compare a company to its industry, not to other industries.
Two companies can both grow revenue 20% — but one might be buying that growth at a loss while the other is earning it. Always check:
Net Income ÷ Shares Outstanding = EPS.
If a company earns $1 billion but issues so many new shares that EPS shrinks, individual shareholders lost ground. Watch for share dilution — it's a hidden cost of growth.
A great income statement tells a story: "We sold more, kept more of what we sold, and turned that into real profit per share — without giving away the company through dilution."
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