Kalshi, Polymarket and the new sportsbook-brand apps let you trade on the same games a sportsbook takes bets on. So what’s actually different? The short answer: who you’re trading against, how prices are set, how you pay, who regulates it and who can use it. This guide compares prediction markets and traditional sports betting side by side, checked October 2026.
Side by side
| Sportsbook | Prediction market | |
|---|---|---|
| Who you bet against | The bookmaker | Other traders, matched by an exchange |
| Who sets the price | The bookmaker, with a margin built in | Supply and demand on an order book |
| How the platform earns | The margin (vig) in every line | A trading fee per contract, plus the spread you cross |
| Selling before the end | Cash-out at the book’s offer, if available | Sell your shares at any time at the market price |
| US regulation | State gaming regulators, state by state | The CFTC, as federal event contracts; several states dispute this for sports |
| Minimum age | Usually 21 for online sports betting | 18 on Kalshi; some apps set 21, such as Novig |
| Limits on winners | Books can limit or close winning accounts | Exchanges profit from volume, not from your losses |
Prices: margin vs spread
A sportsbook builds its profit into the odds: two sides at −110 add up to an implied 104.8%, not 100%. Our no-vig calculator strips that out. On a prediction market, the Yes and No prices add up to about $1, and your costs are the gap between the best buy and sell prices plus a separate fee. On liquid games, the exchange route is often cheaper; on thin markets the spread can cost more than a sportsbook’s margin.
Regulation and where it’s legal
Sports betting in the US is legal state by state, licensed by each state’s gaming regulator, and is still illegal in some states. Prediction markets such as Kalshi argue that their sports contracts are federal event contracts overseen by the Commodity Futures Trading Commission, which is why they’re available in many states without legal sports betting. Several states disagree and have taken prediction markets to court, with mixed results so far, so sports contracts can be unavailable in some states. See our legal guides.
Which is better for you?
- You want the best price on a big game: compare both. Convert the sportsbook line to a no-vig chance and check it against the market price.
- You want to sell early: prediction markets let you sell at any time at the market price.
- You want promos, props and same-game parlays: sportsbooks still offer more of these, though exchanges now offer combos (see Kalshi combos).
- You’re 18–20: some prediction markets are open at 18 where sportsbooks require 21. Check each platform’s rules and your state’s.
Live sports markets
Sports: most traded on Polymarket and Kalshi
Latest price for “Yes”, shown as an implied chance. Polymarket volume in USD, Kalshi in contracts. Updated 3 min ago.
FAQ
Is a prediction market the same as a sportsbook?
Are prediction markets legal where sports betting isn’t?
Do prediction markets limit winning players?
Related: What are prediction markets? · No-vig calculator · Sports markets · Best prediction market apps