How Buying & Selling Actually Works

Placing a stock order looks simple — you open your app, type a company name, choose a quantity, and tap "buy." But behind that tap is a mini-auction happening in milliseconds. Understanding what actually occurs will make you a calmer, smarter investor and save you real money on every trade.

Bid, ask and the spread

At any moment there are two prices for every stock:

• Bid price — the highest price someone is willing to PAY right now.
• Ask price — the lowest price someone is willing to SELL at right now.

Suppose Reliance shows "Bid ₹2,499 | Ask ₹2,501." That means:

• If you want to sell immediately, the best offer waiting is ₹2,499.
• If you want to buy immediately, the cheapest seller is at ₹2,501.

The ₹2 gap between them is the spread. On liquid stocks (heavy volume) the spread is tiny, often a few paise. On illiquid stocks (thin volume) it can be several rupees, and that gap is a real cost you pay every time you trade — you buy a little high and sell a little low.

The order book

Behind those two prices sits the order book — the full queue of pending buy and sell orders:

SELL ORDERS (people wanting to sell)
₹2,505 — 500 shares
₹2,503 — 300 shares
₹2,501 — 1,000 shares   <-- best ask (lowest sell price)

BUY ORDERS (people wanting to buy)
₹2,499 — 2,000 shares   <-- best bid (highest buy price)
₹2,497 — 800 shares
₹2,495 — 600 shares

The bid and ask you see quoted are simply the top of each side of this book. As people place, cancel and fill orders, the book reshuffles constantly. A deep, tightly packed book means the stock is liquid and easy to trade; a thin, gappy one means the opposite. You can read more about that texture in What Is a Stock Exchange?.

Market order vs. limit order

When you place an order you choose one of two types.

Market order

"Buy 100 shares RIGHT NOW at whatever the market offers." It executes immediately at the best available price — the ask for a buy, the bid for a sell. You get in fast, but if the spread is wide or the price is moving, you may pay a little more than the number you glanced at.

Limit order

"Buy 100 shares, but ONLY at ₹2,500 or lower." Your order waits in the queue. If a seller appears at ₹2,500 or below, it fills; if the price never reaches there, it simply expires and you stay in cash — you are never forced into a worse price.

For unhurried long-term investing, limit orders are usually the wiser choice. You are not in a race, so you can name your price and wait. Just keep the limit realistic, close to the live price.

How a trade executes, step by step

Let us trace a real buy:

1. You place a market buy order for 100 shares of Infosys.
2. The exchange checks the order book. The best ask is ₹1,800 with 500 shares available.
3. Your order matches part of that sell order — you get 100 shares at ₹1,800 each.
4. The seller's order is reduced by 100 (they still have 400 queued).
5. The trade is recorded instantly, but the shares are credited to your demat account the next working day (T+1).
6. The money leaves your bank account on T+1 as well.

The matching happens in under a second; the ownership transfer completes at settlement the next day.

Delivery vs. intraday

There are two very different ways to trade, and the difference is central to halal investing.

Delivery (also called "cash" or "equity")

You buy shares and hold them in your demat account. They are genuinely yours: dividends come to you, voting rights are yours, and you can hold for decades. This is real investing and real ownership.

Intraday (often via "MTF" or margin)

You borrow money from the broker to buy more shares than your cash allows, and you must sell the same day before the market closes. You never actually take ownership — you are betting on the day's price wiggle. Intraday charges margin interest (a percentage fee, which is riba) and magnifies both gains and losses through leverage.

Settlement and your timeline

• Day 0 (T): You place your order and it executes. Your app shows it as executed.
• Day 1 (T+1): Settlement. Shares are credited to your demat and money is debited from your bank. Now you truly own them.
• Day 2 onward: The shares are fully yours — to hold for years, or one day pass on to an heir.

During that one-day gap the price can move. If you bought at ₹2,500 and it is ₹2,480 by T+1, you are down ₹20 per share on paper — but you still own the shares, and for a long-term holder that daily wiggle is meaningless.

Common mistakes when placing orders

Setting an unrealistic limit price

If Reliance trades at ₹2,500 and you set a buy limit at ₹2,300 hoping for a bargain, your order will likely never fill. Keep limits within a small band of the live price — usually 1% to 3% — unless you genuinely do not mind never buying.

Using a market order on an illiquid stock

On a thinly traded stock, a market order can fill several rupees away from the last price because the book is so sparse. On illiquid names, a limit order protects you from that nasty surprise.

Panicking over the T+1 paper move

Seeing red before settlement unsettles beginners. It is normal. The trade is done; a small move before the shares land in your demat changes nothing about your long-term decision. What actually matters over years is covered in What Moves Stock Prices.

Quick quiz

Check what you learned about orders

1. You want to buy but only up to a certain price. Which order type should you use?

A market orderA limit orderAn intraday orderA margin order

2. In delivery trading versus intraday trading, what do you actually own?

You own the shares in bothYou own the shares in delivery; in intraday you never take ownership and often use interest-bearing marginYou own the shares in intraday onlyYou never own shares in either

3. Why might a limit buy order never execute?

Because limit orders are illegal in IndiaBecause the price never reached the limit you set, so no matching seller appearedBecause the exchange was closed all dayBecause limit orders always fill instantly

Key takeaways

• Bid is what buyers offer, ask is what sellers want; the spread between them is a real trading cost.
• Market orders fill instantly at the best price; limit orders wait for the price you name.
• Trades match in under a second but settle the next working day (T+1).
• Delivery means you truly own the shares (halal); intraday means borrowing and betting (riba and speculation).
• Set realistic limits, avoid market orders on illiquid stocks, and ignore the T+1 paper wiggle.

Try it

Now that you know HOW to trade, learn what actually moves the prices you are trading. Discover what moves stock prices — earnings, news, macro events, and why long-term investors ignore the noise.