In this guide
Every transaction on PolyGram and Polymarket is processed via a Central Limit Order Book — the identical order-matching system deployed by NASDAQ, NYSE, and all leading financial exchanges worldwide. Grasping how CLOB operates will sharpen your ability to trade prediction markets effectively. Let us walk through the mechanics.
What Is a Central Limit Order Book?
A Central Limit Order Book (CLOB) functions as a digital ledger cataloguing all active buy and sell orders for a given asset, organised by price level and temporal sequence. Upon receipt of a fresh order, the exchange's matching engine seeks to pair it with opposing orders already present in the book.
Within prediction markets, the "asset" refers to a YES or NO contract on a defined outcome. The CLOB for "Will Bitcoin exceed $100K in 2026?" displays all queued orders seeking to acquire YES shares alongside all queued orders seeking to dispose of YES shares (or equivalently, to purchase NO shares).
Reading the Order Book
- Bids (buy orders): Participants prepared to acquire YES shares at a given price threshold or less. Displayed in descending price sequence.
- Asks (sell orders): Participants prepared to dispose of YES shares at a given price threshold or more. Displayed in ascending price sequence.
- Best bid: The uppermost price at which a buyer currently stands ready to transact for YES shares
- Best ask: The lowermost price at which a seller currently stands ready to transact for YES shares
- Spread: The gap separating best ask from best bid. Narrow spread = robust liquidity conditions.
How Orders Match
Upon submission of a market order (acquiring at prevailing rates), the CLOB engine:
- Identifies the current best ask (minimum seller price)
- If your bid price ≥ best ask: execution occurs at the ask price
- Your order gets satisfied in full or in part contingent on accessible supply
- Any remaining unfilled quantity enters the book as a fresh bid
Limit orders function comparably yet trigger only when market conditions align with your predetermined threshold.
Why CLOB Matters for Traders
- Price improvement: Your order settles at the most favourable available rate, avoiding arbitrary charges
- Transparency: All pending orders remain visible to you prior to executing a transaction
- No counterparty risk: The CLOB mechanism, rather than a human intermediary, fulfils your transaction
- Better prices vs AMM: CLOB-based prediction markets typically deliver narrower spreads relative to automated market makers (AMMs)
CLOB vs AMM in Prediction Markets
Polymarket's CLOB (integrated with PolyGram) diverges from AMM-based prediction markets such as earlier iterations of Augur. CLOBs furnish granular pricing and substantial depth; AMMs provide perpetual liquidity availability yet incur wider slippage on substantial orders. For the majority of prediction market scenarios, CLOB represents the preferable architecture.
FAQ
- What is slippage in a CLOB prediction market?
- Slippage materialises when your order volume surpasses the liquidity accessible at the optimal price, forcing portions of your order to settle at less favourable rates. PolyGram calculates and communicates projected slippage prior to finalising any transaction.
- Can I place limit orders on PolyGram?
- Absolutely — you may establish an upper threshold for YES share acquisition or a lower threshold for NO share acquisition. Your order persists within the CLOB until market conditions satisfy your threshold or you elect to withdraw it.
- How often does the CLOB update?
- The Polymarket CLOB refreshes instantaneously without interruption. PolyGram synchronises these refreshes with negligible delay via its CLOB connectivity layer.