What Is an Order Book? Prediction Market Trading Explained | HiYesN…

Updated: 2026-06-28 · Author: HiYesNo Editorial Team · Type: Glossary

An order book is a real-time list of all outstanding buy and sell orders on a prediction market like HiYesNo. It shows exactly how many shares people want to buy (bids) and sell (asks) at each price level. Because prices are set entirely by user activity, the order book is the clearest signal of where the market consensus stands.

On HiYesNo, every prediction event uses the order book model. You can place a limit order to wait for your target price, or hit an existing order to trade instantly. A deeper order book means better liquidity and less slippage when you trade.

Key concepts

• Bid: the highest price a buyer is currently willing to pay for a share.
• Ask: the lowest price a seller is currently willing to accept.
• Bid-ask spread: the gap between the best bid and best ask; a tighter spread means better liquidity.
• Depth: the total volume of orders at various price levels; greater depth means you can trade larger sizes without moving the price.
• Limit order: an order placed at a specific price that rests in the book until a counterparty matches it.
• Market order: an order that executes immediately against the best available opposing order, prioritizing speed over price.

Frequently asked questions

• What is the difference between an order book and an AMM?
  An order book matches real user bids and asks; an automated market maker (AMM) prices shares algorithmically from a liquidity pool. Order books give you more control over your entry price.
• Why is the spread sometimes very wide?
  A wide spread usually means low liquidity. You can wait with a limit order, or accept a less favorable price to trade immediately.
• Does the order book price equal the true probability?
  A price of $0.65 implies roughly 65% market-implied probability, but thin liquidity or information asymmetry can distort this.
• How do I read the order book on HiYesNo?
  Open any event detail page and switch to the order book view to see live bids and asks for YES and NO shares.