Spread (bid–ask)
Updated November 10, 2026
The spread is the gap between the highest bid (best buy offer) and lowest ask (best sell offer). To buy yes now, you pay the ask—often higher than the mid-price shown on charts.
Mid-price displays 55¢, but the book shows bid 53¢ / ask 57¢. You buy 20 yes at 57¢, so your implied entry probability is 57%, not 55%. Selling later hits the bid at 53¢, so round-trip spread cost matters for short-hold positions.
What the spread costs in dollars
Twenty yes at the 57¢ ask cost $11.40. Selling the same 20 straight back at the 53¢ bid returns $10.60. The $0.80 difference is the spread, 4¢ on each of 20 contracts, paid before the price has moved at all. Measured from the 55¢ mid, half of it is paid on the way in and half on the way out.
Fees come on top. Each trade carries the $0.01 per-contract exchange fee and Lumina’s 0.35% commission on trade value. On the 20-contract buy that’s $0.20 in exchange fees and $0.0399 in commission (0.35% of $11.40). Statements and confirmations show it rounded to the cent.
The no side mirrors the yes quote. With yes at 53¢ bid / 57¢ ask, buying no costs about 47¢ (100¢ − 53¢) and selling no returns about 43¢ (100¢ − 57¢), the same 4¢ gap from the other direction.
What makes a spread wide or narrow
The spread reflects how many orders are resting near the price. A contract with steady volume and orders on both sides tends to quote a cent or two wide. A thin or newly listed contract can show a much wider gap, such as 40¢ bid / 52¢ ask, and a quote like that says more about how little has traded than about the probability: its 46¢ midpoint isn’t a well-defined 46%. Liquidity and spread move together for that reason.
Spreads can also widen for a while around scheduled news, such as the minutes before a data release, when traders pull or reprice their orders. The spread is part of why the price you pay differs from the share price shown on a chart.
FAQ
What is a good bid-ask spread on a prediction market?
Narrower is cheaper to trade. On a $1 contract, a spread of a cent or two is narrow; a double-digit gap usually means little has traded.
Why did I pay more than the price on the chart?
Charts often show the mid or the last trade. Buying now fills at the ask, which sits above the mid by half the spread.
Is the bid-ask spread a fee?
No. It’s the gap between the best bid and best ask from other traders’ orders. Fees are separate: the $0.01 per-contract exchange fee per side plus Lumina’s 0.35% commission on trade value.