To most people, a corporate earnings report looks like a mass of spreadsheets and legal jargon. To a professional analyst, it is a detailed picture of how healthy a company's business really is.

Analysts do not read these reports for the story. They compare what a company promised with what it actually delivered, which is why an earnings release can move the share price so sharply.

Most of a report can be skimmed. A handful of numbers, from revenue and guidance to three core profitability measures and a few warning signs, tell investors most of what they need to know.

Revenue and Guidance

The first layer is revenue, the top line, and the company's guidance, its own forecast for the coming quarters. Revenue shows whether a product is selling, while guidance shows whether that demand is expected to last.

Markets react to whether results beat or miss expectations. A company can report record revenue and still see its shares fall if it lowers guidance, because share prices reflect expected future cash flows. It also helps to separate organic growth from growth bought through acquisitions, which can make revenue look stronger than the core business is.

The Three Core Metrics

Earnings per share (EPS) is the company's profit divided by its outstanding common shares, and it is the main measure of profitability. Watch for share buybacks: by reducing the number of shares, they can lift EPS without any increase in actual profit.

Operating margin is operating profit as a share of revenue, after costs such as materials, wages and overheads, so it measures efficiency. If revenue grows while margins shrink, the company may be paying too much for its growth, often because of rising raw material prices or inefficient operations.

Free cash flow (FCF) is the cash left after operating expenses and capital spending on equipment and facilities. Accounting earnings can be shaped by non-cash items, which makes FCF one of the most reliable numbers in a report. It is the money that pays for dividends, debt repayment and research.

The Consensus Gap

The reported figure matters less than the consensus gap, the difference between the result and what analysts expected. If the market expects $1.00 in EPS and the company delivers $1.01, that counts as a beat.

Traders also watch the whisper number, an unofficial expectation that circulates among investors and is often higher than the official forecast. A company can beat consensus and still see its stock drop if it misses the whisper number, especially when the share price was already so high that a standard beat could not justify it.

Red Flags in the Data

Beyond the main numbers, look for signs that results are being polished. If inventories grow much faster than sales, the company may be producing goods it cannot sell, which can lead to write-downs, cuts to the recorded value of those goods, in later quarters.

A sudden jump in accounts receivable, sales recorded but not yet paid for, can mean the company is stuffing the channel: pushing products onto distributors to meet quarterly targets.

Many companies also report adjusted, or non-GAAP, earnings that exclude one-time costs. GAAP stands for generally accepted accounting principles, the standard US accounting rules. If one-time costs appear every quarter, they are really regular operating expenses.

Baruch Lev, professor of accounting and finance at NYU Stern, argues that the spread of non-GAAP earnings is a symptom of weaknesses in standard accounting rather than a solution to them. Comparing the adjusted and standard figures side by side shows exactly what was left out.

The Long View

An earnings report covers 90 days, but analysis works best over several years. One weak quarter can be a temporary setback, while three consecutive quarters of shrinking margins point to a deeper problem.

Before the next earnings season, pick one company you follow and track its guidance, operating margin and free cash flow over the last few quarters. Reading each report as a review of management's performance makes it easier to act on data rather than headlines.