Order Book and 5-Level Market Depth on NSE

What the Order Book Actually Shows on NSE

An order book is the live, electronically maintained list of every pending buy and sell order for a single instrument, sorted by price and time. On the NSE, what your broker app shows you is not the full order book. Brokers display the 5-level market depth, also called Market By Price (MBP), which reveals the best five buy prices and the best five sell prices, along with the quantity and the number of separate orders sitting at each of those ten price points.

The full depth, every single resting order, is the Market By Order (MBO) feed. Retail traders almost never see MBO. It is part of the more expensive tick-by-tick data feed that proprietary desks and algo firms subscribe to. So when this page talks about reading the order book, it means the 5-level depth window you actually get inside Zerodha Kite, Upstox, Groww, Angel One, Dhan or any NSE-registered broker terminal.

The book is continuously matched by the NSE trading engine on a strict price-time priority basis. The best-priced order wins first, and among orders at the same price, the one entered earliest gets filled first. Understanding this priority is the difference between knowing why your limit order sat unfilled all day and knowing how to place it so it actually trades.

A Real 5-Level Market-Depth Snapshot (Reliance)

Below is an illustrative but realistic 5-level depth window for Reliance Industries (RELIANCE) on NSE around a Last Traded Price (LTP) of Rs 2,950. The left side is the BID (buyers), the right side is the ASK / OFFER (sellers). Read the bid from the top down as the highest price anyone is currently willing to pay. Read the ask from the top down as the lowest price anyone is currently willing to sell at. These figures are illustrative and change tick by tick.

Here the best bid is Rs 2,949.85 (top buyer) and the best ask is Rs 2,950.10 (top seller). The bid-ask spread is Rs 0.25, which for a liquid large cap like Reliance is tight. The total bid quantity (17,950) is smaller than the total ask quantity (20,300) across the visible five levels, a mild hint that near-term selling interest slightly outweighs buying interest, though this can flip within seconds.

Notice level three on the bid side: 6,100 shares across just 14 orders. A single chunky order can dominate a level. Notice the ask side level four: 7,250 shares across 30 orders, lots of small sellers stacked together. The number of orders column tells you whether a level is one big player or a crowd of small ones, which matters because one large order can be pulled instantly, while a crowd is stickier.

Bid, Ask, Spread and Why the Gap Costs You Money

The bid-ask spread is the gap between the highest buy price and the lowest sell price. It is a hidden cost on every trade. If you buy at the ask and immediately sell at the bid, you lose the spread instantly, before brokerage and taxes even apply. In Reliance above, that spread is Rs 0.25 per share. On 100 shares, crossing the spread once costs Rs 25. On an illiquid small cap where the spread might be Rs 2 or Rs 3, the same round trip could cost hundreds of rupees per 100 shares.

This is why liquid instruments matter. Nifty 50 stocks, index futures, and at-the-money index options usually carry spreads of a few paise to a rupee. Far out-of-the-money options, illiquid mid and small caps, and stock options on thin underlyings can carry spreads of 5 to 20 percent of the price, which quietly destroys returns. The order book is where you check this before you commit.

• Best bid: the highest price a buyer will currently pay. You sell into this with a market sell order.
• Best ask (offer): the lowest price a seller will currently accept. You buy from this with a market buy order.
• Spread: best ask minus best bid. Tighter is cheaper to trade and signals higher liquidity.
• Mid price: the average of best bid and best ask, often used as the fair reference for placing limit orders.

How a Market Order Eats the Book: A Worked Slippage Example

Suppose you place a market buy order for 10,000 shares of Reliance using the ask side of the snapshot above. A market order takes whatever is available, climbing the ask levels until your full quantity is filled. It does not stop at the best price. Walking up the book, illustratively: 3,100 shares fill at Rs 2,950.10, then 5,400 at Rs 2,950.25, then the remaining 1,500 at Rs 2,950.40.

Your average fill is about Rs 2,950.23, not the Rs 2,950.10 you saw at the top of the book. That difference of roughly Rs 0.13 per share across 10,000 shares is about Rs 1,300 of slippage, purely from the order eating three levels of depth. In a thinner stock the same 10,000-share order might walk through ten levels and cost you several rupees per share. This is the single most important practical reason to read the depth window before sending a large market order: if the visible quantity is small relative to your size, switch to a limit order or split the order.

Order Book in F&O: A Bank Nifty Options Example

The order book matters even more in derivatives because option spreads can be wide and lot sizes are fixed. Take Bank Nifty, whose F&O lot size is 30. Imagine a monthly Bank Nifty 52,000 call (CE) showing a best bid of Rs 248 and a best ask of Rs 252 in its depth window. That is a Rs 4 spread, which on a 15-quantity lot is Rs 60 of cost just to cross once.

Say you buy 2 lots (30 quantity) at the ask of Rs 252, paying Rs 252 x 30 = Rs 7,560 in premium. The underlying rallies and you exit when the option depth shows a best bid of Rs 300, selling 30 at Rs 300 for Rs 9,000. Gross profit is Rs 9,000 minus Rs 7,560 = Rs 1,440 (illustrative). But your real profit is after costs. Brokerage on a discount broker is roughly Rs 20 per order, so Rs 40 for buy plus sell. STT on options is charged at 0.1 percent on the sell-side premium value, which is 0.001 x 9,000 = Rs 9. Add exchange transaction charges, SEBI fees, GST at 18 percent on brokerage and exchange charges, and stamp duty on the buy. Net profit lands a little below the Rs 1,440 gross, illustratively around Rs 1,370 to Rs 1,390.

The lesson from the order book here is that the quoted bid and ask, not the LTP, decide your fill. If you had panicked and sold at market into a thin bid of Rs 290, your exit would have been worse. Always read the depth on the option itself, weekly contracts expire on their scheduled weekly expiry and thin out fast near expiry, widening spreads exactly when you most want to exit.

Reading Buying Versus Selling Pressure (And Its Limits)

Traders often look at the total bid quantity versus total ask quantity at the bottom of the depth window to gauge short-term pressure. If total bids massively outweigh total asks, it can suggest more buyers are queued up, and vice versa. In the Reliance snapshot, asks (20,300) edge out bids (17,950), hinting at slightly more visible supply near current price.

However, treat this as a weak, fleeting signal, not gospel. The 5-level window shows only a sliver of true intent. Large players deliberately hide size, slicing big orders into small clips using iceberg or disclosed-quantity orders so the book understates real demand. Resting orders can be cancelled in milliseconds. And market orders that never appear in the book can sweep through levels instantly. So a book that looks heavily bid can still drop on a single large market sell that was never visible.

• Heavier total bid quantity can hint at near-term support, but it is easily faked or pulled.
• Heavier total ask quantity can hint at near-term resistance or overhead supply.
• Watch how levels refill after they get hit, persistent refilling on the bid is a stronger signal than a one-time big number.
• Combine depth with price action, volume and the day's range. The order book alone is not a trading system.

Order Types and How They Sit in the Book

Different order types behave differently in the order book. A limit order rests visibly in the book at your chosen price until matched or cancelled, adding liquidity. A market order never rests, it immediately consumes the opposite side and removes liquidity. Understanding which side of this you are on, adding or removing liquidity, explains both your fill quality and the cost you pay.

A common and costly mistake on NSE is using a plain SL-Market order in an illiquid contract. When triggered, it becomes a market order and walks the book. If the book is thin, like a far OTM option near expiry, your stop can fill several rupees away from the trigger. Reading the depth tells you whether an SL-Market is safe or whether an SL-Limit (with a buffer) is the better choice.

Spoofing, Layering and SEBI Oversight

Because the order book is visible, some participants try to deceive it. Spoofing is placing large orders with no intention to execute, purely to create a false impression of demand or supply, then cancelling them before they fill. Layering stacks multiple deceptive orders across levels to push price in a desired direction. Both are forms of market manipulation and are illegal.

In India, the Securities and Exchange Board of India (SEBI) and the exchanges run surveillance systems that flag suspicious order-and-cancel patterns, and SEBI has penalised entities for manipulative order placement. For a retail trader, the practical defence is humility: do not over-trust a single giant order on the book. If a 50,000-share wall appears at one ask and keeps reappearing whenever it is nibbled, it might be genuine supply, or it might be designed to scare you. Watch whether it actually absorbs trades or simply vanishes when price approaches.

Order Book Versus Trade History (Time and Sales)

Beginners confuse the order book with the trade history. The order book shows intentions, what people say they want to do at various prices right now. The trade history, or time and sales, shows reality, the actual executed trades with price, quantity and timestamp. The order book is the future and the trade history is the past.

Pros read both together. If the ask side is loaded but the trade tape shows aggressive buying repeatedly lifting the offer, the resting supply is being absorbed and price may push up despite the heavy ask. Conversely, a thin-looking book with heavy selling on the tape warns of weakness. Neither window alone tells the full story, and on NSE both update in real time inside your broker terminal.

• Order book (market depth): pending, unexecuted intentions sorted by price.
• Trade history (time and sales): completed trades, the ground truth of what actually transacted.
• Use them together: compare what the book promises against what the tape delivers.

Practical Checklist Before You Hit Buy or Sell

Make reading the depth window a habit, not an afterthought. The few seconds it takes to glance at the order book before sending a trade routinely saves more in slippage and bad fills than any indicator on your chart. This is especially true around the open, around major news, and near option expiry when books thin out and spreads blow open.

• Check the spread: a wide spread means a costly entry and exit, demand a tighter price or trade something more liquid.
• Add up visible quantity on the side you are crossing, if your order is bigger than that, expect slippage.
• Prefer a limit order when the book is thin, and an SL-Limit over SL-Market in illiquid contracts.
• Watch whether levels refill or vanish after being hit, behaviour matters more than the static number.
• Factor in real costs: brokerage, STT, exchange charges, GST and stamp duty all apply to the fill the book gives you.
• Remember the tax treatment: delivery STCG 20 percent, LTCG 12.5 percent above Rs 1.25 lakh, F&O as business income at slab.

Sources and Further Reading

For authoritative data and contract specifications, refer to NSE India, SEBI and Zerodha Varsity. All prices, quantities, premiums and profit figures on this page are illustrative examples, not live quotes or advice, and never a promise of returns. Always confirm current lot sizes, tax rates, STT and transaction charges on the official source before you trade.

Sources and Further Reading

For authoritative data and further reading on this topic, refer to NSE India, SEBI (Securities and Exchange Board of India) and Zerodha Varsity. Always confirm current rules, rates and contract specifications on the official source before you trade.