Module 2 · Market Instruments · Lesson 5
Earnings
The single number that drives long-term stock prices.
Quick Answer
What Are Earnings in Investing?
Earnings are the profit a company has left after paying its expenses, interest and taxes. Investors use earnings to judge whether a business is genuinely making money and becoming more profitable over time. The main figures to check are earnings per share, earnings growth, operating margin, the P/E ratio and free cash flow. For the underlying maths, our valuation and ratios visual lessons take it step by step.
In the short run, stock prices move on narratives, fear, and noise. In the long run, almost nothing matters except one thing: earnings. Earnings simply means net profit the money left over after a company pays its expenses, taxes, and costs. If a company’s earnings double over a decade, its stock will almost always follow. If a company’s earnings stagnate or fall, no marketing campaign, CEO charisma, or sector hype will save its share price.
Earnings — also called net income, net profit, or “the bottom line” — represent what remains after a company pays all its costs, taxes, and interest. They are the cash the business actually generated for its owners. Revenue is impressive. Earnings are real. A business with $100 billion in revenue and zero earnings is selling more than it costs to make. A business with $5 billion in revenue and $1 billion in earnings is twenty times healthier financially.
This lesson is the practical guide to reading earnings. Five metrics. One real case study. The traps that fool beginners. By the end you will be able to glance at a company and answer the only question that matters in the long run: is this business actually making money, and is it making more of it every year?
The price wobbles. The earnings climb. Over decades, the price has no choice but to follow. Investors who track earnings rather than prices get clarity on what they actually own. Investors who track prices get noise, anxiety, and the urge to trade.
|
~7%
S&P 500 long-run real EPS growth |
5–20
Buffett’s preferred P/E range |
109×
Apple’s diluted EPS multiple, FY2005 to FY2024 |
Sources. Robert Shiller CAPE data. Apple 10-K filings. Berkshire Hathaway shareholder letters. May 2026.
Part One
The idea in plain English
Earnings show how much profit a company reports. Investors care about earnings because long term stock prices usually need long term profits to support them.
How this looks in real investing
If revenue grows 20 percent but earnings are flat, costs may be rising. If earnings grow faster than revenue, margins may be improving.
What to avoid
Looking only at the headline EPS number without checking revenue, margins, cash flow and management guidance.
Do this before moving on
For one company, compare revenue growth, operating income growth and free cash flow growth.
The five earnings metrics that matter
Hundreds of earnings-related metrics exist. Five carry 90 percent of the signal. If you understand these, you can evaluate any company in any industry.“Your goal as an investor should be to purchase, at a rational price, a part-interest in an easily understandable business whose earnings are virtually certain to be materially higher five, ten, and twenty years from now.”
— Warren Buffett
Part Two
Case study: Apple’s earnings, FY2005 to FY2024
Apple’s reported diluted earnings per share (EPS) rose from $1.56 in fiscal 2005, equivalent to about $0.0557 on the later split-adjusted share basis, to $6.08 in fiscal 2024. The 2024 figure is approximately 109 times the comparable 2005 level. This compares fiscal-year endpoints 19 years apart, rather than a 20-year annual return.
Apple diluted EPS: one comparable share basis
| Fiscal year | As reported | Later split factor | Comparable EPS |
|---|---|---|---|
| 2005 | $1.56 | 7 × 4 = 28 | $1.56 ÷ 28 ≈ $0.0557 |
| 2024 | $6.08 | 1 | $6.08 |
Calculation: $6.08 ÷ ($1.56 ÷ 28) ≈ 109.13. The 2005 filing already reflects its February 2005 split; only the 2014 seven-for-one and 2020 four-for-one splits are applied here.
Sources: Apple’s 2005 Form 10-K, 2024 fiscal-year financial statements, and official stock-split history.
These are reported annual diluted EPS figures, not adjusted non-GAAP earnings or a shareholder return calculation. The 2024 EPS includes the reported one-time tax charge. EPS is affected by profits and the diluted share count, including buybacks. Share prices also depend on valuation and expectations, so earnings growth does not guarantee a matching stock return. Our earnings calendar shows who reports and when.
“If you can follow only one bit of data, follow the earnings. Earnings make or break an investment in equities.”
— Peter Lynch
Part Three
How to read an earnings report in 15 minutes
Annual reports run hundreds of pages. You do not need to read them all. Five steps cover the signal.Step 1
Find the 10-K online
Step 2
Check EPS trend
Step 3
Compare margins
Step 4
Check cash flow vs profit
Step 5
Calculate P/E
Part Four
The earnings traps that fool beginners
Companies have decades of practice making earnings look better than they are. Watch for these five patterns. One-off gains dressed as recurring earnings. A company that sells a building or wins a lawsuit reports the proceeds as profit. EPS jumps. The headline looks great. Recurring earnings have not changed. Always check whether the latest quarter included any non-recurring items, listed clearly in the notes. Aggressive share buybacks pumping EPS. EPS can rise even with flat profits if the company buys back shares to reduce the denominator. This is not the same as real growth. Check whether net income (the top of the ratio) is actually growing or whether the company is just shrinking the share count. Accounting choices that smooth earnings. Inventory methods, depreciation schedules, and revenue recognition rules can all be adjusted within legal limits. Compare cash flow to earnings. If they diverge persistently, something is being smoothed. “Adjusted” or “pro forma” earnings. Many tech companies report “non-GAAP” or “adjusted” EPS that excludes “one-time” expenses — except many of those expenses recur every year (stock-based compensation, restructuring charges). Always check the GAAP number alongside the adjusted one.| Trap | Signal It’s Happening | Defence |
|---|---|---|
| One-off gains | Sudden EPS spike vs trend | Read footnotes to income statement |
| Buyback inflation | EPS rises, net income flat | Watch net income alongside EPS |
| Earnings smoothing | Reported earnings >> cash flow | Compare to operating cash flow |
| Adjusted EPS abuse | Big gap between GAAP and “adjusted” | Always read GAAP first |
| Peak-cycle profits | Record earnings in cyclical industry | Compare 10-year EPS average |
“If you aren’t willing to own a stock for ten years, don’t even think about owning it for ten minutes.”
— Warren Buffett
Investor Wisdom
What the great investors said about earnings
Ten quotes on profit, patience, and the long arithmetic of compounding.
“Your goal as an investor should be to purchase, at a rational price, a part-interest in an easily understandable business whose earnings are virtually certain to be materially higher five, ten, and twenty years from now.”
— Warren Buffett
Means. Future earnings are the only thing that justifies a stock price. Focus there.
Apply. Before buying, write down your estimate of EPS in 5 and 10 years. If you can’t, you don’t understand the business.
“If you can follow only one bit of data, follow the earnings.”
— Peter Lynch
Means. Of all the data points, earnings are the most predictive of long-term returns.
Apply. Open the earnings page before the price page every time you check a stock.
“Everyone has the idea of owning good companies. The problem is that they have high prices in relation to assets and earnings.”
— Charlie Munger
Means. A great business at a stupid price is a bad investment. Always check what you’re paying per dollar of earnings.
Apply. Use P/E as your price sanity check.
“In the short run, the market is a voting machine. In the long run, it is a weighing machine.”
— Benjamin Graham
Means. Sentiment drives daily prices. Earnings drive decade prices.
Apply. Hold five years before judging a buy. Earnings need time to play out.
“Cash is a fact. Profit is an opinion.”
— Alfred Rappaport
Means. Reported profit can be shaped by accounting. Cash flow cannot lie as easily.
Apply. Whenever earnings rise sharply, check cash flow alongside.
“The function of economic forecasting is to make astrology look respectable.”
— John Kenneth Galbraith
Means. Macro forecasts are mostly noise. Company-level earnings analysis is the real edge.
Apply. Spend your research time on company filings, not on market predictions.
“The biggest secret in investing is that there is no secret. You just have to find businesses with growing earnings and pay reasonable prices.”
— Peter Lynch (paraphrased)
Means. Investing isn’t mysterious. Growing earnings + reasonable price = good return over time.
Apply. If a stock fails either test, skip it. Both must be present.
“The investor of today does not profit from yesterday’s growth.”
— Warren Buffett
Means. Past earnings tell you what was. Future earnings tell you what you’ll get.
Apply. Use history to inform forecasts, but pay only for future cash flows.
“Behind every stock is a company. Find out what it’s doing.”
— Peter Lynch
Means. The ticker is shorthand for an operating business. Look through the symbol.
Apply. Read the 10-K before buying. The chart is not the company.
“Time is the friend of the wonderful company, the enemy of the mediocre.”
— Warren Buffett
Means. Quality businesses get better with time; weak ones decay. Hold the right ones longer.
Apply. If earnings are reliably growing, give the position more rope, not less.
Key Takeaways
Six things to take from this lesson
| 01 | Earnings — net profit — are the long-run engine of stock prices. Track earnings before tracking prices. |
| 02 | Five metrics dominate: EPS, P/E ratio, earnings growth rate, operating margin, and free cash flow. |
| 03 | A P/E ratio shows years of profit you’re paying for. Compare across companies and time periods. |
| 04 | Free cash flow exposes accounting tricks. If reported earnings rise but cash flow doesn’t, look closer. |
| 05 | Apple’s share price tracked Apple’s earnings over 20 years. The pattern holds for almost every quality company. |
| 06 | Beware traps: one-off gains, buyback-inflated EPS, smoothed earnings, “adjusted” non-GAAP figures, peak-cycle profits. |
Five Commitments
What you commit to before moving on
Read each one. If you cannot honestly commit to it, the lesson is not finished.
| I. | Before buying any stock, I will look at five years of EPS, not just the latest quarter. |
| II. | I will calculate the P/E ratio and compare it to both the company’s own history and the industry average. |
| III. | I will always check free cash flow against reported earnings, especially when earnings look exceptionally good. |
| IV. | I will read GAAP earnings before “adjusted” or “pro forma” headline numbers. |
| V. | I will not buy any company whose earnings I cannot project at least roughly five years out. |
End of Lesson
Module 2 . Lesson 5 of 21 . Continue to Lesson 6 . Debt.
Primary sources and further reading
Use these references to check the definitions, methods and risks discussed in this guide. Examples are for learning and do not predict investment results.- SEC: Beginners’ Guide to Financial Statements
- SEC Investor.gov: How to Read a 10-K
- SEC Investor.gov: How to Read a 10-K or 10-Q
- FINRA: Evaluating Stocks
Education only. This guide provides general information, not personal investment, financial or tax advice. Check current rules and official filings before making a decision. To keep up without reading every headline, the stock news summarizer condenses the coverage of any ticker.
