In this guide
Key takeaway: Liquidity stands as the paramount consideration for anyone trading prediction markets. When liquidity runs deep, you benefit from compressed spreads, instantaneous order execution, and pricing that reflects true market consensus. Polymarket dominates this space with $1.5B+ in total traded volume; alternative venues typically operate at substantially lower levels of activity.
Prediction market liquidity shapes your entire trading journey — influencing both the cost basis of your entries and the speed at which you can unwind exposure. Yet many newcomers prioritise market selection over liquidity assessment. This article unpacks why depth and spreads deserve your primary attention.
What is liquidity?
Liquidity in financial markets refers to the ease with which you can transact an asset without materially shifting its quoted price. Within prediction markets, three distinct elements comprise liquidity:
- Depth: Quantity of shares resting at successive price tiers within the order book
- Spread: Distance separating the highest bid level (buyers' best offer) from the lowest ask level (sellers' best offer)
- Volume: Aggregate share turnover across a defined timeframe
Consider a market displaying 10,000 shares offered at 48 cents and 10,000 shares sought at 50 cents — this exhibits strong liquidity. Conversely, a market with merely 50 shares on either side separated by a 10-cent gap demonstrates poor liquidity conditions.
Why liquidity matters for traders
Insufficient liquidity erodes profitability through multiple channels:
- Wider spreads: Your transaction costs increase both upon entry and exit
- Slippage: Substantial position sizing pushes execution prices unfavourably
- Trapped positions: Absence of willing counterparties prevents timely position closure before market settlement
- Price inaccuracy: Sparse trading activity produces quotes that diverge from underlying probability assessments
How to measure prediction market liquidity
Prior to committing capital, evaluate these metrics:
- Order book depth: PolyGram's depth visualisation tool displays cumulative buy and sell pressure across price levels
- 24h volume: Elevated trading activity correlates with improved fill probability and tighter execution
- Number of unique traders: Markets attracting 100+ distinct participants typically possess sufficient depth for standard retail positions
- Spread percentage: Target markets where the spread remains below 3 cents (3%) to minimise transaction friction
Which platforms have the most liquidity?
| Platform | Cumulative volume | Avg. spread |
| Polymarket | $1.5B+ | 1-3 cents |
| Kalshi | $500M+ | 2-5 cents |
| Betfair Exchange | N/A (sports-focused) | 1-2% on sports |
| Augur/Azuro | $50M+ | 5-15 cents |
How market makers create liquidity
Institutional liquidity providers simultaneously post bids and offers, capturing the spread differential whilst supplying execution availability to the broader participant base. Polymarket incentivises this activity through fee reductions and MATIC token distributions. PolyGram's proprietary order aggregation system synchronises with Polymarket's central book, guaranteeing PolyGram participants access to equivalent depth and pricing as those trading directly on Polymarket.
Tips for trading illiquid markets
- Deploy exclusively limit orders — avoid market execution in sparse conditions
- Divide substantial positions across multiple price tiers
- Exercise patience: establish your target price and await counterparty interest rather than accepting adverse crossing costs
- Account for temporal dynamics — thinly-traded markets frequently consolidate liquidity as resolution approaches
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