What Is a Stock Exchange? NYSE, Nasdaq and the TSX

A stock exchange is the organised marketplace where shares of public companies are bought and sold — the meeting point that connects millions of buyers and sellers.

What an exchange does

At its heart, a stock exchange matches people who want to buy a stock with people who want to sell it, and records the price they agree on. Instead of hunting down a private buyer for your shares, you place an order and the exchange finds the other side almost instantly.

A modern exchange is essentially a vast, high-speed computer system that receives orders, matches them by price, and publishes the results in real time. The floor traders in old photographs have largely been replaced by servers.

The major exchanges

New York Stock Exchange (NYSE)

The largest exchange in the world by the total value of listed companies. Based in New York, it lists many long-established firms and is known for its historic trading floor.

Nasdaq

Also U.S.-based, the Nasdaq was the first fully electronic exchange and is home to many large technology companies. When people mention the "tech-heavy Nasdaq," this is what they mean.

Toronto Stock Exchange (TSX)

Canada's primary exchange, operated by TMX Group. It's especially known for financial, energy, and mining companies. Smaller and earlier-stage Canadian companies often list on its sister venue, the TSX Venture Exchange.

Listed vs private companies

Only public companies trade on an exchange. To become listed, a company goes through an initial public offering (IPO) and must meet the exchange's requirements — things like minimum size and regular financial reporting. Private companies aren't traded this way, which is part of why public companies face far more disclosure rules.

Trading hours and the ticker

Each exchange has set hours — North American exchanges generally run 9:30 a.m. to 4:00 p.m. Eastern on weekdays. Trades placed outside those hours happen in pre-market and after-hours sessions, which are thinner and can be more volatile. Every listed company has a short ticker symbol used to identify it for trading.

Who keeps it fair?

Exchanges operate under the watch of regulators. In the United States that's largely the Securities and Exchange Commission (SEC); in Canada, securities regulation runs through provincial regulators and self-regulatory bodies such as CIRO. Their job is to promote fair, transparent trading and to police fraud and manipulation.

Indexes: measuring the exchange

You'll often hear that "the market rose today." That usually refers to a market index — a number that tracks a basket of stocks on an exchange, like the S&P/TSX Composite or the S&P 500 — used as shorthand for how the overall market is doing.

The takeaway: a stock exchange is the trusted, regulated marketplace that makes buying and selling shares fast, orderly, and transparent — the stage on which the whole market plays out.