Where shares trade — and why there's a price at all

A share only has a market price because there is a place where buyers and sellers meet continuously and agree, transaction by transaction, on what it's worth right now. In India that place is overwhelmingly two electronic exchanges: the National Stock Exchange (NSE) and the BSE. They are not shops that hold inventory and sell it to you at a sticker price. They are matchmakers — vast, fast, computerised marketplaces that pair the people who want to buy with the people who want to sell, and get out of the way.

Sitting above all of it is the regulator, the Securities and Exchange Board of India (SEBI), which writes and enforces the rules that keep the marketplace honest — disclosure norms, trading limits, penalties for manipulation. You don't deal with SEBI directly, but the reason you can trust that a printed price is a real, arm's-length transaction rather than a fiction is that there's a referee with teeth standing behind the game.

The order book: a live ledger of intentions

At the heart of every exchange is the order book — a continuously updating, two-sided list of everyone's intentions for a given stock. Every would-be buyer posts the highest price they're willing to pay, called a bid. Every would-be seller posts the lowest price they're willing to accept, called an ask (or offer). The exchange's computer stacks these up: all the bids sorted on one side, all the asks on the other.

• The best bid is the highest price anyone is currently willing to buy at.
• The best ask is the lowest price anyone is currently willing to sell at.
• The gap between them is the spread — tight for big, heavily-traded stocks; wide for thinly-traded ones.
• Behind the best prices sit depth — stacks of further orders at worse prices, waiting their turn.

The book is matched by a strict, public rule: price first, then time. The best price gets filled before any worse price, and among orders at the same price, whoever arrived first gets filled first. There is no favouritism and no human deciding who trades — it's an algorithm applying the same rule to everyone, billions of times a day. Understanding this rule alone dissolves most conspiracy theories about why an order did or didn't fill.

Market order vs limit order: the choice you make every time

Every order you place is, at heart, one of two kinds, and the difference is about what you're willing to give up.

• A market order says: 'fill me right now, at whatever the best available price is.' You get speed and certainty of execution, but you accept the current spread and whatever price the book hands you.
• A limit order says: 'fill me only at this price or better.' You control the price exactly, but you might wait — and you might never get filled if the stock walks away from your limit.

Why the price moves with no news at all

This is the part that genuinely confuses newcomers. A stock can rise 1% on a sleepy Tuesday afternoon with not a single headline anywhere. How? Because price is set by the balance of orders, not by news directly. If, at the current price, more rupees want to buy than to sell, the eager buyers must lift their bids to find willing sellers, and the price ticks up step by step. If more want out than in, sellers must lower their asks to find buyers, and it ticks down.

News matters — enormously — but only because it changes people's willingness to buy or sell. A good earnings report makes holders less willing to part with the stock and outsiders keener to own it; that shift in willingness reshapes the order book, and the price moves. But plenty of order-book shifts have nothing to do with news at all: a mutual fund deploying the month's SIP money, an index fund rebalancing, someone selling shares to pay for a wedding. The mechanism is always the order book. News is just one of many things that nudges it.

The market price is not the truth about a company. It is the temporary clearing point between everyone who currently wants in and everyone who currently wants out.

Liquidity: the quiet thing that matters most

Liquidity is how easily you can buy or sell a meaningful amount without moving the price against yourself. It is the single most underrated concept for a new investor, because it is invisible when markets are calm and brutally, expensively visible the moment you need to exit in a hurry.

A heavily-traded large company might see crores of rupees change hands every minute. You can buy ₹1 lakh of it and the price won't even notice you were there — there's a deep stack of orders to absorb you. A tiny smallcap might trade just ₹2 lakh in an entire day. Try to sell ₹50,000 of it and you've just dumped a quarter of the day's volume onto a near-empty book — the price can crater 5% against you before you're done, simply because there aren't enough buyers waiting.

Where the shares came from in the first place

Before a stock can trade on an exchange at all, it has to get listed, and this is worth understanding because it reveals a distinction that confuses a lot of beginners. When a company first sells shares to the public — an Initial Public Offering, or IPO — the money goes to the company itself (or to the early owners selling their stake). That's the primary market: shares being created and sold for the first time. Everything that happens afterwards on NSE and BSE is the secondary market: existing shareholders trading already-issued shares amongst themselves.

The practical consequence: when you buy a share of an established company on the exchange today, the company receives nothing — your rupees go to whoever sold you the share. You're trading second-hand ownership. The company only raises fresh money in the primary market, at the IPO or in later fund-raises. This is why a soaring share price doesn't directly put cash in the company's bank account; it benefits the company indirectly (cheaper future fund-raising, valuable stock to pay staff) but the daily trading is owners swapping among themselves.

Guard rails: circuit breakers and price bands

The market is not allowed to go completely haywire unchecked. To stop panics and runaway moves from feeding on themselves, exchanges impose circuit breakers and price bands — limits on how far a price can move in a single session before trading pauses or halts.

A broad market crash beyond certain thresholds can trigger a market-wide halt, freezing trading for a cooling-off period so that fear has a moment to subside and people can think. Individual stocks, especially smaller ones, have their own upper and lower price bands; hit the band and the stock is 'locked' — frozen at that limit with orders piling up on one side and nobody on the other. These rails exist to protect ordinary investors from the very stampedes that illiquidity makes possible.

Two exchanges, one price

NSE and BSE list most of the same large companies, so the same stock has a price on both. You might wonder how they stay in sync. The answer is arbitrage: if a stock were even slightly cheaper on one exchange, fast traders would instantly buy there and sell on the other, pocketing the difference — and that very act pushes the two prices back together within a whisker. For all practical purposes you'll trade on whichever exchange your broker routes your order to, and the price difference between them is usually just paise.