Understanding Liquidity in Prediction Markets
Key takeaway: Liquidity is the single most important factor for prediction market traders. Deep liquidity means tight spreads, fast fills, and accurate prices. Polymarket leads with $1.5B+ in cumulative volume; most competitors offer a fraction of that depth.
Prediction market liquidity determines everything about your trading experience — from the price you pay to how quickly you can exit a position. Yet most beginners focus on which markets are available rather than how liquid they are. This guide explains why liquidity matters more than anything else.
What is liquidity?
In financial markets, liquidity measures how easily you can buy or sell an asset without significantly moving its price. In prediction markets specifically, liquidity has three components:
- Depth: How many shares are available at each price level in the order book
- Spread: The gap between the best bid (highest buy price) and best ask (lowest sell price)
- Volume: How many shares change hands over a given period
A market with 10,000 shares on the bid at 48 cents and 10,000 on the ask at 50 cents is liquid. A market with 50 shares on each side at a 10-cent spread is illiquid.
Why liquidity matters for traders
Low liquidity costs you money in several ways:
- Wider spreads: You pay more to enter and exit positions
- Slippage: Large orders move the price against you
- Trapped positions: If nobody wants to buy your shares, you cannot exit before resolution
- Price inaccuracy: Illiquid prices do not reflect true probabilities
How to measure prediction market liquidity
Before placing a trade, check these indicators:
- Order book depth: On PolyGram, use the depth chart to visualise buy and sell walls
- 24h volume: Higher volume means more active trading — easier to get filled
- Number of unique traders: Markets with 100+ unique traders are typically liquid enough for retail sizes
- Spread percentage: Aim for markets with spreads under 3 cents (3%) for cost-efficient trading
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
Professional market makers place simultaneous buy and sell orders, profiting from the spread while providing liquidity to other traders. On Polymarket, market makers are incentivised with reduced fees and MATIC rewards. PolyGram's own liquidity engine mirrors Polymarket's order book, ensuring PolyGram users get the same depth as direct Polymarket traders.
Tips for trading illiquid markets
- Use limit orders exclusively — never market-buy in thin markets
- Split large orders across multiple price levels
- Be patient: set your price and wait for a fill rather than crossing the spread
- Consider the time horizon — illiquid markets may become liquid closer to resolution
Trade on the most liquid prediction market platform. Start trading on PolyGram →