Stock markets are organised systems for buyers and sellers to exchange ownership in public companies. Understanding how they actually work — who the participants are, how prices are set, and what drives market movements — gives you a significant edge over investors who only know how to place orders without understanding the mechanism behind them.
What Is a Stock Market?
A stock market is a regulated marketplace where shares in publicly listed companies are bought and sold. It serves two distinct functions: the primary market, where companies raise capital by issuing new shares to the public for the first time (an Initial Public Offering, or IPO), and the secondary market, where investors buy and sell those shares among themselves after the IPO.
When most people refer to "the stock market," they are referring to the secondary market — the continuous, real-time marketplace where millions of transactions occur every trading day. The price at which a company's shares trade in this secondary market reflects the collective judgment of all buyers and sellers about the company's current and future value.
The three major exchanges covered by FIY are the New York Stock Exchange (NYSE) and NASDAQ in the United States, the Toronto Stock Exchange (TSX) in Canada, and the National Stock Exchange (NSE) and Bombay Stock Exchange (BSE) in India — each with its own listed companies, trading hours, regulatory framework, and market characteristics.
How Stock Prices Are Set
Stock prices are set by supply and demand — the continuous negotiation between buyers (who want to pay as little as possible) and sellers (who want to receive as much as possible). This negotiation happens through an order book maintained by the exchange, which records all pending buy and sell orders at various price levels.
When a buyer's willingness to pay (bid) matches a seller's willingness to accept (ask), a transaction occurs and the matched price becomes the new "last price" displayed for the stock. This process repeats thousands of times per second for actively traded securities during market hours.
| Market Participant | Role | Impact on Price |
|---|---|---|
| Retail Investors | Buy and sell through brokerage accounts | Small individual orders; significant in aggregate |
| Institutional Investors | Pension funds, mutual funds, hedge funds | Large block orders that can move prices significantly |
| Market Makers | Provide continuous bid/ask quotes to ensure liquidity | Maintain narrow spreads; absorb imbalanced order flow |
| Algorithmic Traders | High-frequency trading firms executing at machine speed | Provide liquidity and arbitrage; dominate short-term price formation |
| Index Funds/ETFs | Buy/sell baskets of stocks based on index changes | Predictable, rules-based flows at known times (rebalancing) |
Market Hours and Trading Sessions
Each exchange operates during defined hours, outside of which regular trading is not possible. Understanding these hours matters particularly for investors managing cross-market portfolios.
- NYSE and NASDAQ (U.S.): 9:30 AM – 4:00 PM Eastern Time, Monday–Friday. Pre-market trading 4:00–9:30 AM ET; after-hours trading 4:00–8:00 PM ET (both with reduced liquidity).
- TSX (Canada): 9:30 AM – 4:00 PM Eastern Time, Monday–Friday — matching U.S. hours for most of the year, with minor differences during daylight saving time transitions.
- NSE and BSE (India): 9:15 AM – 3:30 PM Indian Standard Time (IST), Monday–Friday. Pre-open session 9:00–9:15 AM IST. India operates in a single time zone, making market hours consistent across the country.
Stock Market Indices: The Market's Scoreboard
A stock market index is a statistical measure tracking the performance of a selected group of stocks — a representative sample or complete set of the listed companies on an exchange. Indices serve as benchmarks for investor performance and as barometers of overall market health.
The most important indices for investors operating in our three covered markets are the S&P 500 (500 large U.S. companies), the Dow Jones Industrial Average (30 large U.S. companies), and the NASDAQ Composite (all NASDAQ-listed companies, heavily weighted toward technology) in the U.S.; the S&P/TSX Composite Index in Canada; and the Nifty 50 and BSE Sensex in India.
Most major indices are market-cap weighted — meaning larger companies have proportionally greater influence on the index's movements. When someone says "the market was up 1% today," they typically mean the dominant index for their market rose 1% — which may or may not reflect the experience of smaller companies in that market.
What Moves Stock Markets
Stock markets are influenced by an enormous range of factors, operating simultaneously across different timeframes. Understanding these drivers helps investors contextualise price movements without overreacting to short-term noise.
Short-term drivers include: corporate earnings reports, economic data releases (inflation, employment, GDP), central bank interest rate decisions, geopolitical events, and sentiment shifts driven by news flow. These factors can cause significant intraday or week-to-week volatility without necessarily changing the long-term fundamental picture for a company or market.
Long-term drivers include: corporate earnings growth over time, changes in interest rates and their effect on the discount rate applied to future earnings, technological and demographic shifts that create new industries and destroy old ones, and the long-run relationship between equity returns and economic growth. Over periods of 10 years or more, short-term noise largely cancels out and long-term fundamentals dominate returns.
How Markets Are Regulated
Stock markets in all three jurisdictions we cover operate under strict regulatory frameworks designed to ensure fairness, transparency, and investor protection. In the U.S., the Securities and Exchange Commission (SEC) and FINRA oversee market participants. In Canada, the Investment Industry Regulatory Organization of Canada (IIROC, now CIRO) and provincial securities regulators govern the industry. In India, the Securities and Exchange Board of India (SEBI) regulates all market participants and exchanges.
These regulators set rules on disclosure requirements (companies must publish financial results on defined schedules), trading practices (insider trading and market manipulation are illegal and actively prosecuted), and investor protections (account insurance, dispute resolution mechanisms, and know-your-client requirements for brokerages).
Conclusion
Understanding how stock markets actually work — the mechanics of price formation, the role of different participants, the structure of exchanges, and the drivers of short and long-term movements — transforms you from a passive participant reacting to prices into an informed investor who understands why prices are doing what they are doing. This context does not guarantee better returns, but it does provide the framework needed to make rational, disciplined decisions across any market environment.
Circuit Breakers and Market Halts
All major exchanges have mechanisms to pause trading when markets move too rapidly — preventing panic-driven cascades and giving participants time to assess information. In U.S. markets, market-wide circuit breakers halt all trading for 15 minutes if the S&P 500 falls 7% or 13% from the previous close; a 20% decline triggers a full-day halt. Individual stocks also have circuit breakers when they move more than a defined percentage within a short window.
In Indian markets, SEBI-mandated circuit filters operate at both the index level (10%, 15%, and 20% market-wide halts) and the individual stock level (upper and lower price bands of 2%, 5%, 10%, or 20% depending on the stock's assigned circuit category). Understanding these mechanisms helps investors avoid placing orders that may be unexpectedly halted or that execute at unexpected prices during volatile conditions.
Pre-Market and After-Hours Trading
Trading in U.S. equity markets occurs not just during regular hours (9:30 AM–4:00 PM ET) but also in extended sessions — pre-market (typically 4:00–9:30 AM ET) and after-hours (4:00–8:00 PM ET). These sessions allow investors to react to earnings reports, economic data, or news events that occur outside regular hours.
However, extended-hours trading carries significantly higher risk than regular hours trading. Bid-ask spreads widen substantially due to lower participation, price moves can be exaggerated and then partially reversed when regular hours begin, and execution quality is generally much poorer. Retail investors are strongly advised to use limit orders exclusively during extended hours and to treat pre-market and after-hours prices as directional indicators rather than precise transaction levels.