Prediction markets used to be mostly politics. Now Polymarket and Kalshi list a lot of games. If you come from sportsbooks, a few things work differently.
How a sports contract works
"Will the Lakers beat the Celtics?" Yes trades at 58¢. If you buy Yes and the Lakers win, each share pays $1. If not, $0. The price is the market's probability: 58¢ ≈ 58%.
What's different from a sportsbook
- No American odds. Convert in your head: 58¢ is about -138, 40¢ is +150.
- You can sell anytime. Up at halftime? Lock it in.
- Prices move with people, not a bookmaker. That means overreactions, and opportunities.
- Rules matter. Check how the market handles overtime, postponements and cancellations. It's all in the rules.
- Liquidity varies. Big games are deep. Smaller games can have wide spreads.
Where the edge is
- Compare with the sportsbooks. If the books say 52% and the market says 58%, someone's wrong.
- Late news. Markets sometimes react slower than books to lineup changes, sometimes faster.
- Emotional pricing. Popular teams can trade above their real chances.
Key takeaways
- Price = probability, payout = $1 per share
- You can sell before the game ends
- Read the rules on overtime and postponements
- Compare prices with sportsbooks to find value
The bottom line
Sports on prediction markets is the same game with different rules. Learn the format, compare prices and you'll find spots sportsbook-only bettors never see.