Liquidity
Updated November 10, 2026
Liquidity is how easily you can buy or sell a contract without moving the price. Deeper order books mean tighter bid–ask spreads and less slippage when you enter or exit a position.
A headline macro contract shows 68¢ bid / 70¢ ask with size at both levels: you can buy 500 yes near 70¢ without pushing the price. A niche contract shows 41¢ / 58¢ with thin size: a 100-contract buy might lift the ask to 62¢, raising your effective entry cost.
How to read liquidity on a contract
Three things on a contract's screen tell you how liquid it is. The spread is the gap between the best bid and the best ask. Depth is how many contracts are resting at those prices and the levels just behind them. Recent volume tells you whether the quote reflects trades from the last few minutes or from days ago.
A narrow spread with little size behind it is only liquid for small orders. In the headline contract above, 500 contracts can trade near 70¢ because that size is resting on the book. In the niche contract, the 58¢ ask holds fewer than 100 contracts, so a 100-contract order runs past it to 62¢.
Liquidity also changes what the price means as a probability. The mid of the deep book is 69¢, and both sides sit a cent away from it. The mid of the thin book is 49.5¢, with the ask 8.5¢ above it and the bid 8.5¢ below. That quote places the market's estimate somewhere between 41% and 58%, a much weaker reading than 69% give or take a cent. Market efficiency covers the conditions under which a price is a strong estimate.
What thin liquidity costs you
The spread is a cost you pay to get in and out. Buy at the ask and sell straight back at the bid, with nothing else changing, and you lose the width of the spread on every contract.
- Round trip in the deep book
- 4.357¢
- Buy at 70¢, sell at 68¢: 2¢ spread plus 2.357¢ in fees
- Round trip in the thin book
- 19.4095¢
- Buy at 58¢, sell at 41¢: 17¢ spread plus 2.4095¢ in fees
Fees apply to each trade on top of the spread. On Lumina that is a $0.01 per-contract exchange fee plus a 0.35% commission on trade value, so getting in and out of a position means paying them twice. A sale buys the other side, so its commission is on that side's price: 32¢ when you sell at 68¢, 59¢ when you sell at 41¢.
Liquidity varies by contract and over time. A contract listed the same day has had little time to attract orders on either side, and a question that draws wide attention tends to collect more of them than a niche one.
FAQ
What does liquidity mean in a prediction market?
How easily you can buy or sell a contract close to the quoted price. The practical signs are a narrow bid–ask spread and enough size resting on both sides for the order you want to place.
Is a liquid market more accurate?
Liquidity is one of the conditions behind reading a price as a good estimate, along with time on the board and clear settlement terms. A liquid market can still be wrong, and the contract still settles at $1 or $0.
What is slippage?
The difference between the price you expected and the average price you actually fill at. It grows when your order is larger than the size resting at the best price, as when a 100-contract buy in the thin example lifts the ask from 58¢ to 62¢.