Exchanges and prediction markets
Kalshi, Polymarket US and Novig: you bet against other people, not a bookmaker, and pay a trading fee instead of a built-in margin.
Updated September 27, 2026 · TrueEdge Academy
An exchange does not take the other side of your bet — another user does. There is no house position, so there is nothing for the venue to protect by limiting you. The venue charges a fee instead of building a margin into the price: some take commission on winnings, while Kalshi and Polymarket US charge on each trade at fill, win or lose — see how Kalshi's fees work.
What changes in practice
Prices are usually tighter, sometimes dramatically so on liquid markets. There is no house to restrict an account for winning. In exchange, liquidity is finite and visible: the price you see is only good for the size actually resting on the book, and taking more than that moves the price against you.
Why the Order Book screen is separate
When both legs of a play are exchange prices, there is no sportsbook anywhere in it — no sportsbook limit risk, and a trading fee instead of vig. That is a different risk profile from a book-to-book arb, so it gets its own screen rather than being mixed in.