How the Stock Market Actually Works

What a share of stock actually is

A share of stock is a small piece of ownership in a real company — not a ticker symbol on a screen, and not a bet on a number going up. When you buy one share of a company, you own a tiny fraction of everything that company has: its buildings, its patents, its cash in the bank, and its future profits.

Say a company has 1 billion shares outstanding and you own 100 of them. You technically own one hundred-millionth of that company. That's a small slice, but it's real — you're entitled to your proportional share of profits (through dividends, if the company pays them) and you typically get to vote on major company decisions, like electing the board of directors.

Why prices move: supply, demand, and expectations

A stock's price moves for one simple reason: at any given moment, more people want to buy than sell (price goes up), or more want to sell than buy (price goes down). But what actually drives that shift in buyers and sellers is expectations about the future, not just what's happening today.

This is why a company can report record profits and still see its stock price fall. If investors expected even higher profits, the "beat" is actually a disappointment relative to expectations, and sellers outnumber buyers. Prices are constantly re-pricing the future, not just reacting to the present.

Where stocks are traded

Stocks trade on exchanges — the two biggest in the U.S. are the New York Stock Exchange (NYSE) and the Nasdaq. These exchanges are essentially giant, highly regulated marketplaces that match buyers with sellers in fractions of a second.

Every stock has a "bid" (the highest price a buyer is currently willing to pay) and an "ask" (the lowest price a seller is currently willing to accept). The gap between them is the "spread." Market makers — firms whose job is to keep trading smooth — often sit in the middle, helping ensure there's almost always someone on the other side of your trade.

Bull markets, bear markets, and corrections

These terms get thrown around constantly, and they have specific meanings. A bull market is a sustained period of rising prices, generally with optimism about the economy. A bear market is a drop of 20% or more from a recent high, usually tied to fears about the economy. A correction is a smaller, shorter drop — typically 10% to 20%.

These aren't just labels — they help investors calibrate their expectations. Corrections happen fairly often (roughly once a year on average) and are considered a normal, healthy part of markets. Bear markets are rarer and more serious, but historically, markets have always eventually recovered and gone on to new highs.

Key terms

Share

A single unit of ownership in a company.

Bid / Ask

The price buyers are willing to pay (bid) versus what sellers want (ask).

Exchange

A regulated marketplace, like the NYSE or Nasdaq, where stocks are bought and sold.

Bull market

A sustained period of generally rising stock prices.

Bear market

A drop of 20% or more in prices from a recent high.

P/E ratio

A stock's price divided by its earnings per share, used to gauge whether it's expensive or cheap.