In this guide
Every transaction on PolyGram and Polymarket flows through a Central Limit Order Book — the identical matching system employed by NASDAQ, NYSE, and all leading financial exchanges worldwide. Grasping how CLOB operates enhances your effectiveness as a prediction market participant. This guide walks you through the fundamentals.
What Is a Central Limit Order Book?
A Central Limit Order Book (CLOB) functions as a digital ledger capturing all active purchase and sale 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 corresponding orders positioned on the opposite side of the book.
Within prediction markets, the "asset" represents a YES or NO contract stake in a particular event. The CLOB governing "Will Bitcoin exceed $100K in 2026?" displays each queued order seeking YES contracts and each queued order offering YES contracts (or equivalently, seeking NO contracts).
Reading the Order Book
- Bids (buy orders): Participants prepared to acquire YES contracts at a designated price or lower. Arranged in descending price sequence.
- Asks (sell orders): Participants prepared to dispose of YES contracts at a designated price or higher. Arranged in ascending price sequence.
- Best bid: The uppermost price at which a buyer currently stands ready to purchase YES contracts
- Best ask: The lowermost price at which a seller currently stands ready to vend YES contracts
- Spread: The gap separating best ask from best bid. Narrow spread = robust market participation.
How Orders Match
Upon submission of a market order (acquire at prevailing rate), the CLOB engine:
- Identifies the current best ask (minimum seller rate)
- If your bid rate ≥ best ask: transaction settles at the ask rate
- Your order receives full or partial execution contingent upon obtainable depth
- Remaining unexecuted portions lodge in the book as a fresh bid
Limit orders behave identically yet trigger execution solely when prices attain your chosen threshold.
Why CLOB Matters for Traders
- Price improvement: Your order settles at the most advantageous obtainable rate, not a predetermined surcharge
- Transparency: All queued orders remain visible to you before committing to any transaction
- No counterparty risk: The CLOB engine, rather than an individual market maker, processes 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 (powering PolyGram) diverges from AMM-driven prediction markets such as earlier iterations of Augur. CLOBs furnish granular pricing and substantial order depth; AMMs deliver perpetual liquidity availability yet incur broader slippage on substantial transactions. For the preponderance of prediction market scenarios, CLOB architecture prevails.
FAQ
- What is slippage in a CLOB prediction market?
- Slippage materialises when your order magnitude surpasses available depth at the optimal rate, forcing portions of your order to settle at inferior rates. PolyGram calculates projected slippage prior to transaction confirmation.
- Can I place limit orders on PolyGram?
- Absolutely — you may designate a ceiling rate for YES contracts or a floor rate for NO contracts. Your order remains lodged in the CLOB until prices attain your threshold or you withdraw it.
- How often does the CLOB update?
- The Polymarket CLOB refreshes perpetually without interruption. PolyGram synchronises these refreshes with negligible latency via its CLOB connection infrastructure.