What You Own When You Buy a Stock

Stocks are the part of most long-term portfolios expected to do the heavy lifting, and also the part that can fall by a third in a few months. Both facts come from the same source: a share of stock is a share of a business, with all of that business's upside and none of its guarantees. This chapter explains what you actually own, what moves the price, what the long record shows, and the risks that matter for an ordinary investor.

What a share actually is

A company that issues stock divides its ownership into shares. If a company has ten million shares and you own one thousand of them, you own one ten-thousandth of the business: its buildings, its products, its cash, its debts and, most importantly, its future profits.

That ownership comes with four things.

• A claim on profits. Profits can be paid out as dividends or kept and reinvested to grow the business. Either way, they belong to the owners.
• A vote. Common shareholders usually vote on the board of directors and major decisions such as mergers, typically one vote per share.
• Limited liability. If the company fails, you can lose what you paid for the shares, but creditors cannot come after your other assets.
• Last place in line. If the company is wound up, lenders and bondholders are paid before shareholders. Owners get what is left, which can be nothing.

Most shares are common stock. Preferred stock pays a fixed dividend that must be paid before common dividends, usually carries no vote, and has limited room to rise in price. It behaves more like a bond than a stock, and most individual investors never need it.

What moves the price

A stock's price is set every moment by buyers and sellers agreeing on a trade. Over long periods, prices follow the company's profits: a business that earns more each year tends to be worth more. Over short periods, prices also respond to things that have little to do with any one company.

• Expectations about profits. Prices move on news that changes what investors expect a company to earn, which is why a company can report a record year and still see its price fall if the record was smaller than expected.
• Interest rates. When safe investments such as Treasury bonds pay more, investors demand more from stocks, and prices tend to fall. When rates fall, the reverse.
• The economy and the industry. Recessions, new technology, regulation and commodity prices can lift or sink whole sectors at once.
• Mood. Fear and enthusiasm push prices further than the news alone would justify, in both directions.

The practical point is that day-to-day moves tell you very little about a business. The longer you hold, the more the result depends on profits and the less on mood.

What the long record shows

From 1928 to 2025, US large-company stocks with dividends reinvested returned an average of 10.02% a year, compounded. Over the same years a 10-year Treasury bond returned 4.53%, 3-month Treasury bills 3.37%, and inflation averaged 3.04%. After inflation, stocks grew buying power by about 6.78% a year.

Those averages turn into very different outcomes over a working life. The examples below take one sum and grow it for thirty years at each asset's historical average return after inflation, so every result is in today's dollars.

In today's buying power, the stock path ends near $71,564, the bond path near $15,401 and the bill path near $11,039. That gap is the reward investors have historically received for owning businesses and accepting their ups and downs. It is an average over a long and specific stretch of American history, not a promise, and it was never delivered smoothly: stocks lost money in 26 of the 98 calendar years, and in their worst year, 1931, returned -43.84%.

The risks that matter

Market risk. The whole market can fall at once, and diversification within stocks does not prevent it. In 2008 US large-company stocks returned -36.55%, and in 2022 -18.04%.

Single-company risk. One company can fail completely, and well-known names have gone to zero. This risk can be almost entirely removed by owning many companies at once, usually through an index fund that holds hundreds or thousands of them. The risk of one company is the one risk you are not paid extra to carry, because it is so easy to avoid. It deserves special attention when the company is your employer: your job and your savings would then depend on the same business.

Volatility. Even in good decades, yearly swings of 20% or more happen. Money you will need within a few years can be forced into a sale at a bad moment.

Behaviour. The largest risk for many investors is their own reaction: buying after prices have soared and selling after they have collapsed. Chapter 5 is about setting a stock share you can actually hold through a bad year.

Reading the main valuation numbers

You do not need to value companies to invest in an index fund, but these terms appear everywhere, and knowing them helps you read financial news calmly.

• Price-to-earnings ratio (P/E). The share price divided by the profit per share over a year. A P/E of 20 means investors pay 20 times a year's profits. A high P/E usually means investors expect fast growth; a low one can mean a bargain or a business in trouble. Its inverse, earnings divided by price, is the earnings yield.
• Dividend yield. The yearly dividend divided by the share price. A very high yield can be a warning that the market expects the dividend to be cut.
• Price-to-book ratio. The share price divided by the company's accounting net worth per share. It is most useful for businesses whose value sits in tangible assets, such as banks.
• Market capitalisation. The share price times the number of shares: the market's price for the whole company. Companies are grouped as large, mid and small; the index providers set the cut-offs and revise them over time.

Investors also sort stocks into styles. Growth stocks are companies expected to raise profits quickly, often reinvesting everything and paying little or no dividend. Value stocks trade at low prices relative to profits or assets. Dividend stocks pay out a large share of their profits. Each style has had long periods of leading and lagging the others. A total market index fund holds all of them, in proportion to their size, so you do not have to guess which will lead next.