Guide
What is market depth?
Market depth is a view of the pending buy and sell orders sitting at different price levels around the current price — commonly shown as the order book. It reveals how many shares or contracts people are willing to trade just above and below the last price, so it is a snapshot of available liquidity. Market depth shows resting demand and supply right now; it is not a prediction of where price will move.
What market depth measures
Market depth measures the queue of unexecuted orders waiting at each price. On the buy side are bids — orders to buy at or below the current price — and on the sell side are asks or offers, orders to sell at or above it. Each level shows a price and the quantity waiting there. Together they describe how much it would take to move price up or down, which is the essence of liquidity. In India, exchanges commonly display the best five bid and ask levels.
Reading the bid-ask spread
The highest bid and the lowest ask are the most important rows. The gap between them is the bid-ask spread — the immediate cost of crossing from buyer to seller. A narrow spread with large quantities on both sides signals a deep, liquid market where you can trade size with little slippage. A wide spread with thin quantities signals an illiquid instrument where even a modest order can move price sharply against you.
How to read market depth
Traders scan depth to judge liquidity before committing an order, especially in size. Stacked quantity on the bid side shows resting demand; heavy quantity on the ask side shows resting supply. Watching how orders fill and refresh can hint at short-term pressure. In liquid NSE names and index derivatives, depth is rich and dependable; in small, thinly traded stocks it can be sparse, and a single large order can dominate the entire visible book.
What market depth does not do
Market depth does not predict direction. It is a snapshot that can change in an instant as orders are placed, modified or cancelled. Resting orders are not promises — participants routinely pull or move them, and large displayed quantities can vanish before price reaches them. Depth also shows only what is openly resting in the book; it cannot reveal hidden intent or orders that will appear only later. It describes the present, not the future.
The classic market depth misuse
The frequent error is treating a large resting order as an immovable wall — assuming a big bid will hold price up, or a big ask will cap it. Because orders can be cancelled or repositioned instantly, such conclusions are fragile and easily exploited. Depth is best used to assess liquidity and execution risk, not to predict turning points. Read it as context for placing orders sensibly, never as a forecasting tool.
Common Questions
Frequently Asked Questions
What does market depth tell you?
+It tells you how many buy and sell orders are resting at prices around the current price, which reflects available liquidity. A deep book with tight spreads means you can trade size with little slippage. It describes current resting demand and supply, not future direction.
What is the bid-ask spread?
+The bid-ask spread is the gap between the highest price buyers are bidding and the lowest price sellers are asking. It represents the immediate cost of trading. A narrow spread indicates a liquid market, while a wide spread indicates an illiquid one where orders can move price sharply.
How many levels does market depth show in India?
+Indian exchanges commonly display the best five bid and five ask price levels along with the quantity resting at each. Some interfaces show more detail, but the top five levels carry the most relevance for everyday trading. The best bid and best ask are the most important rows.
Can market depth predict price movement?
+No. Market depth is a live snapshot that changes constantly as orders are placed and cancelled. Large resting orders can disappear before price reaches them, so they are not dependable predictors. Depth is best used to assess liquidity and execution risk, not to forecast direction.