A betting exchange matches you against other bettors instead of a sportsbook. Because nobody is building a big cut into the price, exchange odds are often the best number on the board.
Compare exchange and sportsbook prices ›At a sportsbook, the book sets the price and takes the other side of your bet. On an exchange like ProphetX or Novig, other users post the prices. When you bet the over at +105, someone else is betting the under against you, and the exchange just holds the money and settles the result.
Exchanges make money from a small fee or commission instead of a wide spread, and how that works differs from one exchange to the next. Check the fee before you bet, because it comes out of your edge.
A sportsbook usually prices both sides of a prop at around -110, which adds up to about 104.8%. The extra 4.8% is its cut. On an exchange, bettors compete to offer the best price, so the two sides tend to sit much closer to a fair 100%.
We show ProphetX, Novig, Kalshi, Polymarket US and Underdog's prediction market next to the sportsbooks. Exchanges show up on one side of a lot of our arbs and middles: in our first two days (October 28 and 29, 2026), ProphetX was on one side of about 1 in 3 of the middles on the middles page.
Our +EV list leaves exchanges out, because the fee changes the math. Arbs and middles include them, so add the exchanges you use in My books on the arbs page.
A site where bettors bet against each other instead of against a sportsbook. The exchange matches the two sides, holds the money and charges a fee or commission.
Often, yes. Without a sportsbook's built-in cut, the two sides of an exchange market usually add up closer to 100%, so one side is frequently the best price available.
No. ProphetX is a peer-to-peer exchange: other users take the other side of your bet, and ProphetX settles it.
Yes. Exchanges are often one side of an arb or middle because their prices move differently from the sportsbooks'. Just include the fee in your math.