How to read an income statement

An income statement is one long subtraction: you start from what the company took in and keep deducting costs until you reach what's left. Five lines explain ninety percent of it, and each subtraction along the way produces a margin that says something different.

Why price reflects expectations rather than facts

Before opening any accounts, it's worth understanding what relationship they have with the price, because it isn't the obvious one. A stock's price doesn't reflect what the company has earned: it reflects what the market expects it to earn from here on.

Last quarter's profits are already spent, distributed, or reinvested. Buying a share today doesn't buy you that money: it buys a claim on everything the company generates going forward.

That's why a company can post the best quarter in its history and fall that same day, if what was expected was better still. We covered it fully in the earnings chapter and only the practical consequence is needed here.

So what are the accounts for?

Two things, and neither is predicting tomorrow's price.

Knowing what you're buying. A share is a piece of a real business, with customers, costs, and debts. The accounts are the only verified description of that business that exists.

Judging whether the expectations are reasonable. The market expects something from every company. That something is implicit in the price, and the accounts are what you check it against. If a company trades assuming it will double sales in three years, checking whether it has ever grown at that rate is a basic test.

The goal isn't prediction. It's knowing what you're betting against when you buy, which is exactly what separated investing from speculating in the course's first session.

The three documents, and why you need all three

Almost everyone stops at the income statement, which is why it's worth saying up front that there are three documents and each answers a question the other two don't.

Document	What question it answers	What period it covers
Income statement	Did it make money?	A period: a quarter, a year
Balance sheet	What does it own and owe?	An instant: the period's last day
Cash flow statement	Did money actually arrive?	A period, like the first

Why one isn't enough

A company can make money and run out of cash. It sounds impossible and it's the most common cause of small-business failure: they sold a lot, their customers take ninety days to pay, and meanwhile payroll is due.

A company can hold a lot of cash while losing money, because it just sold a building.

And it can show rising profits alongside debt that will suffocate it in two years, which the income statement doesn't show because debt lives on the balance sheet.

All three together tell the story. One alone tells a third of it, and not always the most important third.

This session covers the first. The next covers the other two, because that's where what almost nobody checks lives.

The five lines of any income statement

Sector, country, and size don't matter: every income statement is the same subtraction. Here's one with round numbers, start to finish.

Line 1: revenue

Everything the company billed during the period. In our example: €1,000 million.

One nuance surprises people: revenue isn't the same as cash collected. A company records the sale when it delivers the product, even if the customer pays in ninety days. That gap between selling and getting paid is the star of the next session.

Line 2: cost of goods sold

What it costs to produce or buy exactly what was sold. In our example: €600 million.

Cost of goods sold includes only what's directly attributable to the product. In a bakery: flour, yeast, and the oven's electricity. Not the shop rent or the accountant's salary, because those exist whether you sell a thousand loaves or none.

Revenue minus cost of goods sold = gross profit: €400 million.

Line 3: operating expenses

What it costs to keep the business running, regardless of how much you sell: administrative salaries, offices, marketing, technology, research. In our example: €250 million.

Gross profit minus operating expenses = operating income: €150 million.

This line is the most important of the five, and the next section explains why.

Line 4: interest and tax

Interest is what the company pays on its debt. Tax is what the state takes. In our example, between the two: €50 million.

Notice these are two items that don't depend on the business itself, but on how the company is financed and where it's taxed. Two identical companies with different debt will have identical operating income and different net income.

Line 5: net income

What's left for shareholders. In our example: €100 million.

It's the number that makes headlines and the one used to calculate earnings per share. It's also the easiest to move with decisions unrelated to selling more, which we'll see next session.

The annotated income statementMade-up company · millions of euros

1. Revenue1,000
2. Cost of goods sold−600
3. Gross margin400
4. Operating expenses−250
5. Operating income150
6. Interest and taxes−50
7. Net income100

Interest is what the company pays on its debt. Taxes are what the tax authority takes. Together, in our example: 50 million.

Two identical companies with different debt will have the same operating income and different net income.

What each margin measures

Each subtraction produces a margin, and each margin answers a different question. With our example:

Margin	Calculation	Result	What question it answers
Gross	400 / 1,000	40%	How much do I make per euro sold, before overheads?
Operating	150 / 1,000	15%	Does the business itself make money doing what it does?
Net	100 / 1,000	10%	What's genuinely left for shareholders?

Gross margin speaks about the product

A high gross margin means the product sells well above what it costs to make. It usually signals brand, proprietary technology, or limited direct competition.

A gross margin narrowing quarter after quarter warns of something before any other number: either costs are rising, or prices have to come down to keep selling. Both are bad news and both show up here first.

Operating margin speaks about the business

It's the most informative of the three, and the one that gets the fewest headlines.

It measures whether the company's activity — what it does every day — generates money, without the answer depending on how much debt it carries or where it pays tax. That's why it's the best one for comparing two companies in the same sector.

Net margin speaks about the final outcome

It's the one in headlines and the noisiest, because decisions unrelated to the business affect it: refinancing debt, an asset sale, a tax adjustment.

A net margin rising while the operating margin falls is a combination worth a second look: the business is doing worse and the final figure still improves, which means the improvement is coming from somewhere else.

The reference bar. Per figures from the Corporate Finance Institute (CFI), an educational institution specialising in corporate finance, a net margin around 10% is considered average; above 20%, high; below 5%, low. They help you get oriented, and only that: the next section explains why.

Why two companies with the same revenue earn different amounts

Because billing isn't earning. Two companies can take in exactly the same and keep completely different amounts, and that doesn't mean one does it better: it can mean they're in different businesses.

A supermarket sells huge volume on razor-thin margins. Out of every €100 purchase it might keep two or three. Its model runs on moving enormous quantities of product with tightly controlled operating costs.

A software company has its cost concentrated in building the product once. Selling licence number one thousand costs practically the same as licence one thousand and one: nothing. Its gross margins can exceed 80%.

Neither is doing badly. They're different models, and comparing one's margin against the other's tells you nothing.

What a margin gets compared against to mean something

Here's the rule that makes everything above useful. A margin in isolation says nothing. It only says something against two references:

Against direct competitors. How does this company's operating margin compare with the three or four companies doing the same thing? That's where signal lives: if everyone in the sector is at 12% and this one is at 18%, it has something the others don't.

Against its own history. What was this margin one, three, and five years ago? A 15% margin doesn't mean the same thing coming down from 22% as coming up from 9%. The direction of travel usually matters more than the level.

That second comparison is the most skipped and the most revealing. A margin narrowing steadily while revenue grows is one of the most reliable patterns that something has got harder: more competition, rising costs, or growth bought by cutting prices.

And a third comparison almost everyone gets wrong

When comparing a quarter, compare it against the same quarter last year, never against the quarter immediately before. The reason is seasonality, and it's stronger than it looks.

A retail chain does an enormous share of its year in the Christmas quarter. Compare that quarter with the next one — January to March — and you'll see a brutal drop in revenue that means absolutely nothing: it means there's no Christmas in February.

The same applies in reverse: comparing the first quarter against the previous fourth would show an invented collapse in any business with a high season.

That's why companies always publish year-over-year comparisons, and why when you see "revenue fell 30% from the previous quarter" in a headline, the first thing to ask is whether that business has a season. Hospitality, retail, tourism, and toys have enormous ones; a utility or a subscription business, much less.

The practical rule: quarter against the same quarter last year to see real growth, and quarter against previous quarter only to see the trend within the year, knowing seasonality is baked into it.

Where to find the accounts, free

All of the above is useless if you don't know where it lives. The good news is it's public and free, and the bad news is almost nobody opens it.

For US companies

The EDGAR database, run by the SEC (Securities and Exchange Commission) — the US securities regulator — is public, free, and requires no registration. You search by ticker.

It holds the three filings that matter: the 10-K is the full annual report, the 10-Q the quarterly one, and the 8-K the material events filing, earnings included.

For Spanish companies

The official registers of the CNMV (Comisión Nacional del Mercado de Valores), Spain's securities regulator, hold annual and half-year financial reports for every listed company, with balance sheet and income statement. They're also public and free.

And there's always the investor relations section of the company's own website, which usually has the same documents in a friendlier format.

How to read a forty-page report without reading it all

Nobody reads a full annual report, and you don't need to. Three sections concentrate most of the value:

The business description. What exactly the company sells and how it makes money. It sounds obvious and it's surprising how many people buy shares unable to answer this.

Management's discussion. In US filings it's the section where the leadership team explains, in their own words, why the numbers came out as they did. It's the closest thing to having it told to you.

The risk factors. The company is required to list everything that could go wrong. It's the least-read section and one of the most honest you'll find, precisely because it's mandatory.

What to remember

• Price reflects what's expected of the future; accounts tell you what you're buying and whether that expectation is reasonable.
• There are three documents and you need all three: a company can make money and run out of cash.
• Five lines explain an entire income statement, and operating margin is the most informative of the three.
• A margin only means something compared against its sector and against its own history.

Related: what expectation a company is really competing against · how to read a full event · the dividend, start to finish