Depth of market is a view of all the resting buy and sell orders stacked at each price level, showing how much size the book can absorb before the price has to move.
Last reviewed 17 September 2025 · Educational, not advice
Behind the single price you see on screen sits a queue of orders. Depth of market, sometimes shown as a depth chart or a depth of market ladder, lays out that queue. It shows how many contracts people are willing to buy at each price below the current level and how many they are willing to sell at each price above it. The best bid and the best ask sit closest together, with more orders resting further out.
Depth tells you how much a market can take. A deep book has large size resting across many price levels, so a sizeable order can trade without pushing the price far. A shallow or thin book has little size, so even a modest order can clear the nearest level and reach into worse prices. That is why the same order can fill cleanly in one market and move the price noticeably in another.
Reading depth helps you judge the cost of trading. If you want to buy more than the best ask can supply, the depth shows the next prices you would pay, which is the slippage you should expect from a market order. It also hints at how steady a quoted price is. A price supported by thick orders on both sides tends to hold, while a price with almost nothing behind it can jump on a single trade. Depth is only a snapshot though. Orders can be added or pulled in an instant, so what the book shows now is not a promise about the next second.
Depth of market is closely tied to liquidity. More depth usually means more liquidity, smoother fills, and a tighter spread. Less depth means wider spreads and more price impact. None of this tells you which way a price will go. It only describes the supply and demand resting in the book right now, and the money you commit is still at risk whichever way the market moves.
The screen shows yes at fifty cents. The depth ladder shows two hundred contracts offered at fifty cents, then only fifty more at fifty one and another fifty at fifty three. A market order for three hundred contracts would clear the fifty cent level, then take the fifty one and fifty three offers, ending with an average price above fifty cents. The depth told you in advance that the book was thin past the first level.
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Depth shows the orders resting now, not where a price will go, and that depth can vanish in a moment. Trading a thin book can fill you at worse prices than you expected. Stake only what you can afford to lose, never to chase a loss, and never on borrowed money. If it stops feeling like a free choice, step back. In the United States you can call or text the helpline on 1-800-GAMBLER or visit ncpgambling.org.
It is a view of the resting buy and sell orders at each price level, showing how much volume is available and how much size the market can absorb before the price moves.
Depth is the raw picture of orders at each price. Liquidity is the broader idea of how easily you can trade without moving the price. More depth usually means more liquidity.
It shows the likely cost of a larger order. A deep book fills near the quoted price, while a thin book can fill you at worse prices, which is slippage.
No. Depth only describes the orders resting now, and those orders can be pulled or added at any moment. It does not tell you which way the price will move.
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