In this guide
Every transaction on PolyGram and Polymarket flows through a Central Limit Order Book — the identical order-matching system deployed by NASDAQ, NYSE, and all leading financial marketplaces. Grasping how CLOB operates elevates your performance 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 temporal sequence. When an incoming order arrives, the matching engine endeavours to pair it with existing orders positioned on the opposing side of the ledger.
Within prediction markets, the "asset" represents a YES or NO share corresponding to a particular event. The CLOB for "Will Bitcoin exceed $100K in 2026?" displays each queued order seeking to acquire YES shares alongside each queued order to dispose of YES shares (or equivalently, to acquire NO shares).
Reading the Order Book
- Bids (buy orders): Participants prepared to purchase YES shares at a designated price or lower. Displayed in descending price sequence.
- Asks (sell orders): Participants prepared to dispose of YES shares at a designated price or higher. Displayed in ascending price sequence.
- Best bid: The uppermost price presently offered by a purchaser for YES shares
- Best ask: The lowermost price presently requested by a seller for YES shares
- Spread: The gap between best ask and best bid. Narrow spread = highly liquid market.
How Orders Match
Upon submitting a market order (acquire at prevailing rate), the CLOB matching engine:
- Identifies the current best ask (minimum seller rate)
- If your bid rate ≥ best ask: execution occurs at the ask rate
- Your order satisfies in full or in part contingent upon obtainable liquidity
- Unsatisfied portions persist in the ledger as a fresh bid
Limit orders function analogously but trigger only when the market arrives at your designated rate.
Why CLOB Matters for Traders
- Price improvement: Your order executes at the most competitive obtainable rate, absent any fixed surcharge
- Transparency: You observe all queued orders before committing to any transaction
- No counterparty risk: The CLOB matching engine, rather than a human liquidity provider, fulfils your transaction
- Better prices vs AMM: CLOB-based markets typically deliver narrower spreads relative to automated market makers (AMMs)
CLOB vs AMM in Prediction Markets
Polymarket's CLOB (deployed through PolyGram) diverges from AMM-based prediction markets such as earlier iterations of Augur. CLOBs furnish granular pricing and order-book depth; AMMs furnish perpetual liquidity availability yet incur broader slippage on substantial transactions. Across most prediction market scenarios, CLOB architecture proves advantageous.
FAQ
- What is slippage in a CLOB prediction market?
- Slippage materialises when your order surpasses the obtainable liquidity at the optimal rate, compelling portions of your order to settle at less favourable rates. PolyGram calculates projected slippage prior to your confirmation of any transaction.
- Can I place limit orders on PolyGram?
- Absolutely — you may designate a ceiling rate for YES shares or a floor rate for NO shares. Your order persists in the CLOB until the market attains your rate or you revoke it.
- How often does the CLOB update?
- The Polymarket CLOB refreshes instantaneously without interruption. PolyGram mirrors these refreshes with negligible delay via its CLOB connectivity.