What a Stock Exchange Actually Does

How stock exchanges bring buyers and sellers together, set rules, and provide the liquidity and price information that investors rely on.

When people say they “bought shares on the stock market”, they usually mean their order was matched with a seller’s order on a stock exchange. Exchanges are marketplaces for securities, and they do more than most people realise.

Matching buyers and sellers

The core job of an exchange is to match orders. Today this is done electronically. Buyers and sellers, usually through brokers, send orders stating how many shares they want and at what price. The exchange’s system matches compatible orders in fractions of a second.

Major exchanges include the New York Stock Exchange and Nasdaq in the United States, the Shanghai and Shenzhen exchanges in China, the London Stock Exchange, and in India, the BSE, founded in 1875 and one of Asia’s oldest exchanges, and the National Stock Exchange, which became India’s largest by trading volume after it launched electronic trading in the 1990s.

Providing liquidity

Liquidity means being able to buy or sell quickly without moving the price much. By gathering many buyers and sellers in one place, exchanges make it easier to trade. Liquidity makes shares more attractive to own, which helps companies raise money.

Price discovery

Every trade reveals what buyers and sellers are willing to pay. Exchanges publish these prices, giving everyone information about what companies are worth. This is called price discovery.

Rules and listing

Exchanges set listing requirements that companies must meet to have their shares traded, including publishing financial reports. They also monitor trading for manipulation, alongside regulators such as the Securities and Exchange Board of India.

Clearing and settlement

After a trade, the shares and money must actually change hands. This process is called clearing and settlement, handled by clearing corporations and depositories. India moved to settling most trades the next business day, known as T+1, by 2023, among the fastest in the world. The United States moved to T+1 in 2024.

From order to ownership

An investor in Pune places an order through a broker's app to buy 10 shares at the current price. The order goes to the exchange, which matches it with a seller's order within milliseconds. The next business day, the clearing corporation ensures the seller's shares move to the investor's demat account and the money moves to the seller. The investor never meets the seller, and doesn't need to trust them, because the system guarantees the trade.

Thinking you buy shares directly from the company

When you buy shares on an exchange, you almost always buy them from another investor, not from the company. Companies raise money only when they issue new shares, such as in an IPO. Most daily trading is between investors.

Key takeaways

Stock exchanges electronically match buyers' and sellers' orders.
They provide liquidity and price discovery.
Listing rules require companies to publish financial information.
Clearing and settlement ensure shares and money change hands, now within one business day in India and the U.S.