A stock exchange is a regulated marketplace where shares and other securities are bought and sold. It brings buyers and sellers together, sets rules for fair trading, and publishes prices so everyone can see them. India's main stock exchanges are the NSE and the BSE.
What a stock exchange is
Companies need money to grow, and investors want places to put their savings. A stock exchange connects the two. When a company first sells shares in an IPO, that is the primary market. After listing, investors trade those shares among themselves on the exchange, which is the secondary market. The exchange does not own the shares or set prices; it provides the system and rules that let trading happen efficiently and fairly.
How it works in India
Investors place orders through SEBI-registered brokers. The exchange's electronic system matches buy and sell orders by price and time. A clearing corporation then ensures that the buyer receives the shares and the seller receives the money, and guarantees settlement even if one side defaults. Shares move into and out of investors' demat accounts held with the depositories. Most equity trades in India settle one working day after the trade.
Exchanges also set listing rules that companies must meet, monitor trading for manipulation, and require listed companies to disclose important information. All Indian exchanges are regulated by SEBI.
Exchanges in India and around the world
In India, the NSE and BSE handle almost all equity trading, while other exchanges focus on areas such as commodities. Major exchanges worldwide include the New York Stock Exchange and Nasdaq in the US, the London Stock Exchange, the Tokyo Stock Exchange, and the Shanghai and Hong Kong exchanges.
A simple example
A company lists its shares on the NSE and BSE after an IPO. A year later, you buy 50 of its shares through your broker. You are not buying from the company; you are buying from another investor who chose to sell. The exchange matches your orders, the clearing corporation settles the trade, and the shares appear in your demat account the next working day.
Why it matters for investors
Exchanges provide liquidity (the ability to buy and sell easily), transparent prices, settlement guarantees and disclosure rules that protect investors. Without them, buying and selling shares would be slow, risky and opaque.
A short history
Organised share trading began centuries ago in Europe, and Asia's oldest stock exchange, today's BSE, started in Mumbai in 1875. For most of history, trading happened face to face on trading floors. From the 1990s, exchanges moved to electronic systems, which made trading faster, cheaper and accessible to investors anywhere. In India, this change, along with the creation of the NSE and dematerialised shares, transformed the market and opened it to millions of new investors.
Example on PositoAI: companies by exchange, worldwide
As on 19 Oct 2026, PositoAI covers about 6,500 companies from 38 countries, listed on many different exchanges. The largest groups, by the exchange each company is tracked on:
NSE (India): 2,038 · Nasdaq (US): about 2,380 · NYSE (US): about 1,520 · London Stock Exchange (UK): about 100 · Hong Kong: 94 · BSE (India, companies tracked only on BSE): 88 · Xetra (Germany): 39 · Euronext Paris (France): 39
Smaller numbers come from Amsterdam, Milan, Madrid, Tokyo, Helsinki and others. Many companies listed in the US are based elsewhere, such as Ireland, Bermuda or Switzerland, which shows how an exchange can attract companies from around the world. Most Indian companies listed on the NSE are also listed on the BSE.
Common misconceptions
"When I buy a share, the company gets my money." In the secondary market, your money goes to the seller, not the company.
"Exchanges decide prices." Prices come from buyers' and sellers' orders.
"Listed means safe." Listing rules set minimum standards; they do not guarantee returns.
Frequently asked questions
What are India's main stock exchanges?
The NSE and the BSE.
What is the difference between primary and secondary markets?
Primary: new shares sold by the company. Secondary: existing shares traded between investors.
Who regulates exchanges in India?
SEBI.
Can I trade without a broker?
No, you need a registered broker.
How to use this on PositoAI
PositoAI tracks companies listed on the NSE and BSE using official exchange closing prices, and also covers companies on exchanges in the US and other markets. Read our guides to the NSE and the BSE. PosiStep 2 of PosiCourse, PositoAI's free stock market course, explains stock exchanges.
Summary
A stock exchange is a regulated marketplace that matches buyers and sellers of securities. IPOs happen in the primary market; everyday trading is the secondary market. In India, the NSE and BSE dominate equity trading, with clearing corporations guaranteeing settlement and SEBI regulating everything. Exchanges provide liquidity and transparency, but listing is not a guarantee of returns.