In this guide
Every transaction on PolyGram and Polymarket is routed through a Central Limit Order Book — the identical order-matching system deployed by NASDAQ, NYSE, and all leading financial exchanges worldwide. Grasping the fundamentals of CLOB mechanics will sharpen your approach as a prediction market participant. Let's explore the mechanics.
What Is a Central Limit Order Book?
A Central Limit Order Book (CLOB) functions as a digital ledger capturing all active buy and sell orders for a given asset, organised by price level and timestamp sequence. When a fresh order enters the system, the matching engine seeks to pair it with opposing orders already residing in the book.
Within prediction markets, the "asset" refers to a YES or NO contract in a particular event. The CLOB for "Will Bitcoin exceed $100K in 2026?" displays every open order seeking YES contracts and every open order offering YES contracts (or equivalently, seeking NO contracts).
Reading the Order Book
- Bids (buy orders): Participants prepared to acquire YES contracts at a stated price or less. Arranged from uppermost to lowermost.
- Asks (sell orders): Participants prepared to dispose of YES contracts at a stated price or more. Arranged from lowermost to uppermost.
- Best bid: The uppermost price at which someone presently seeks YES contracts
- Best ask: The lowermost price at which someone presently offers YES contracts
- Spread: The gap separating best ask from best bid. Narrow spread = robust market depth.
How Orders Match
Upon submitting a market order (acquire at prevailing rate), the CLOB matching system:
- Identifies the prevailing best ask (minimum seller rate)
- If your bid rate ≥ best ask: execution occurs at the ask rate
- Your order fulfils entirely or in part based on obtainable volume
- Remaining portions lodge in the book as a fresh bid
Limit orders operate on comparable principles yet trigger execution solely when the market attains your designated rate.
Why CLOB Matters for Traders
- Price improvement: Your order executes at the most advantageous obtainable rate, rather than a preset surcharge
- Transparency: All pending orders remain visible, enabling informed trading choices
- No counterparty risk: The CLOB matching system, rather than a human intermediary, fulfils your transaction
- Better prices vs AMM: CLOB-structured markets typically deliver narrower spreads relative to algorithmic market makers (AMMs)
CLOB vs AMM in Prediction Markets
Polymarket's CLOB (integrated with PolyGram) diverges from AMM-based prediction platforms such as earlier iterations of Augur. CLOBs deliver granular pricing and substantial depth; AMMs furnish perpetual liquidity availability yet incur broader slippage on substantial transactions. For the bulk of prediction market scenarios, CLOB architecture proves advantageous.
FAQ
- What is slippage in a CLOB prediction market?
- Slippage arises when your order magnitude surpasses the volume obtainable at the optimal rate, forcing portions of your order to settle at inferior rates. PolyGram furnishes projected slippage figures prior to transaction authorisation.
- Can I place limit orders on PolyGram?
- Absolutely — you may establish an upper threshold for YES contracts or lower threshold for NO contracts. Your order persists within the CLOB until market conditions satisfy your rate or you revoke the order.
- How often does the CLOB update?
- The Polymarket CLOB refreshes instantaneously throughout the trading session. PolyGram mirrors these refreshes with negligible delay via its CLOB connectivity.