Overround

The amount by which the prices of all outcomes in a market sum above 100 percent. In a one-winner event, if buying yes on every outcome costs more than 100 cents, the excess is the overround, the market's built-in margin.

Overround is the prediction-market version of the vig. A tighter overround means better value for traders, because you are paying less above fair odds. Our value scanner ranks one-winner events by overround so you can find the least expensive places to trade.