How Trading Works on a Stock Exchange: A Step-by-Step Guide

Every time someone buys or sells shares of a company, a structured sequence of steps takes place behind the scenes. This sequence has changed dramatically over the decades. Once upon a time, brokers stood in a crowded trading ring and shouted out their buy and sell orders. Today, the same trade happens silently on a computer screen in a fraction of a second. Understanding both the old method and the modern one helps explain how a stock exchange actually functions and why the system works the way it does now.

Who is allowed to trade on a stock exchange 🔗

A stock exchange is not a place where the general public can walk in and trade directly. Only members of the exchange or their authorised agents are permitted to deal on its platform. If you want to buy or sell securities, you must work through a stock broker who holds this membership.

In India, this rule is strict and legally enforced. The buying and selling of securities can only be done through brokers who are registered with the Securities and Exchange Board of India (SEBI) and are members of a recognised stock exchange. A broker can be an individual, a partnership firm, or a corporate body. When you approach a broker, you can either place a specific order yourself or rely on the broker’s advice about which securities to buy. The broker acts as the bridge between you and the exchange, executing your instructions on your behalf.

The traditional method: trading on the floor 🔗

For more than a century, Indian stock exchanges followed a manual system known as the open outcry method. This is the process described in most foundational textbooks, and it remains important to understand because it explains why the modern rules exist.

Contacting the broker and placing an order 🔗

The process began with the investor contacting a member broker and deciding which securities to purchase. After this decision, the investor deposited the estimated cost of the transaction with the broker. The broker then handed the task to an authorised clerk, who physically entered the trading hall of the exchange.

Striking the bargain 🔗

Inside the trading ring, the clerk announced the requirement by shouting out the type of security, the quantity, and the price being offered. This had to be done during the allotted dealing time. Another broker would respond to this call, either accepting the offer as it was or making a counter-offer. Through this back-and-forth of voices and hand gestures, a deal was struck. The Bombay Stock Exchange, founded in 1875, operated this way for over a hundred years, with brokers gathering in a ring to call out their orders.

Recording the deal 🔗

Once a bargain was struck, each broker recorded it in a notebook traditionally called a “sauda bahi”. The counterparty broker would sign this book to confirm the transaction. At the close of the trading day, all brokers submitted their transaction records to the exchange so that the deals could be matched and reconciled. This manual recording was slow and left room for error and disputes.

Settlement and the contract note 🔗

On the settlement day under the old system, the broker took delivery of the securities and made the payment. The investor paid the cost of the securities plus a fixed-percentage commission to the broker. The broker then prepared and forwarded a contract note to the investor. This document detailed the quantity, the description of the securities, and the price, including the commission charged. The same procedure applied in reverse when an investor was selling securities rather than buying them.

The contract note has survived into the modern era and remains a legally important document. It is the written proof that a trade took place on your behalf, and a broker is required to issue one for every completed order.

Why the manual system was replaced 🔗

The open outcry method had serious limitations. Physical trading imposed limits on how much volume could be handled and how quickly new information could be reflected in prices. The process was time-consuming, inefficient, and vulnerable to malpractice. A series of market scams in the early 1990s exposed how easily the unregulated, manual system could be manipulated, which eroded investor trust.

The turning point came with the National Stock Exchange (NSE), which was set up in 1992 and introduced fully computerised, screen-based trading from its very first day in 1994. This was a direct challenge to the older method. The NSE used a system that automatically matched buy and sell orders and connected trading computers across the country using satellite technology, making participation possible from almost anywhere.

The Bombay Stock Exchange responded by launching its own electronic platform, BOLT (BSE On-Line Trading), in 1995. Remarkably, the transition from floor trading to screen-based trading at the BSE took only about fifty days, ending a tradition that had lasted over a century.

How trading works today 🔗

The modern process keeps the same logical stages as the old one, but technology has replaced the shouting and the notebooks. The steps are faster, more transparent, and far safer for the investor.

Selecting a broker and opening a Demat account 🔗

The first step is still selecting a SEBI-registered broker who is a member of the exchange. The major difference today is the need for a Demat account, short for dematerialised account. Securities are no longer held as physical paper certificates; they are held in electronic form. To trade, an investor must open a Demat account with a depository participant, such as a bank or a stock broker.

In India, securities in this electronic form are held by two depositories: the National Securities Depository Limited (NSDL) and the Central Depository Services Limited (CDSL). The investor also opens a trading account and completes the mandatory KYC (Know Your Customer) formalities before any trade can take place.

Placing and executing the order 🔗

Once the accounts are ready and funded, the investor places a buy or sell order, usually through a mobile app or website provided by the broker. The exchange’s electronic system then matches this order with a counterparty order at the best available price. A buyer’s order is matched with a seller’s order automatically, and the trade is executed within seconds. The screen-based system cuts down on time, cost, and the chance of fraud compared with the manual ring.

The contract note in the digital age 🔗

The contract note remains a core part of the process. Within 24 hours of a trade being executed, the broker must issue a contract note to the investor. According to the documented trading procedure, this note details the date and time of execution, the number of shares bought or sold, the price, the order type, and the brokerage charged. Issuing a contract note for every completed order is compulsory.

Clearing and settlement 🔗

After execution comes clearing and settlement, the stage where shares and money actually change hands. A clearing corporation steps in between the buyer and the seller, acting as the buyer to every seller and the seller to every buyer. This guarantees that both sides meet their obligations and removes the risk of one party defaulting.

The speed of settlement in India has improved dramatically. The country moved to a mandatory T+1 settlement cycle for equities by January 2023, meaning a trade is settled one business day after it is executed. India was one of the first major markets in the world to do this, ahead of even the United States. On settlement day, the buyer’s account is debited and shares are credited to the Demat account, while the seller delivers shares and receives payment.

The move towards same-day settlement 🔗

India is now pushing the boundaries even further. SEBI introduced an optional T+0 settlement cycle, where eligible trades are settled on the very same day. According to SEBI’s phased rollout, this same-day facility was extended to the top 500 stocks during 2025, running alongside the existing T+1 cycle rather than replacing it. The long-term goal is to make the gap between trade and settlement as close to instant as possible.

Comparing the old and the new 🔗

The shift from the open outcry method to electronic trading did not change the basic logic of a trade. In both systems, an investor instructs a broker, an order is matched with a counterparty, a deal is recorded, a contract note is issued, and the trade is settled. What changed is the mechanism. Shouting in a ring became matching on a server. The sauda bahi became an electronic audit trail. Physical share certificates became Demat entries. A settlement cycle that once stretched over many days now completes the next day, or even the same day.

This evolution has made the market more transparent, more accessible to ordinary investors, and far harder to manipulate. A person in a small town can now buy shares from a phone, something that was impossible when only ring members could trade. The regulatory backbone provided by SEBI and the safety net of clearing corporations are what make this everyday convenience trustworthy.

What do you think? If you were explaining the journey from the trading ring to the trading screen to a friend, which single change do you think mattered most for the ordinary investor? And as settlement moves towards being instant, what new responsibilities do you think this places on a trader who now has far less time to arrange funds or shares?

References

1. https://www.sebi.gov.in/
2. https://www.britannica.com/money/National-Stock-Exchange-of-India
3. https://www.bajajfinserv.in/trading-procedure-on-a-stock-exchange
4. https://www.business-standard.com/markets/news/market-regulator-sebi-widens-scope-of-t-0-settlement-to-top-500-stocks-124121000906_1.html