Baseball
Where MLB prices disagree.
MLB is priced two different ways at the same time: traders set it on Kalshi and Polymarket, and the sportsbooks set it themselves. When the two disagree far enough to survive the fees, it lands here.
Where MLB gets priced
- Prediction markets
- Kalshi and Polymarket
- Sportsbooks
- DraftKings, FanDuel, BetMGM, BetRivers
What we have recorded
16
Gaps found
5.4%
Median gap
136.0%
Biggest gap
- Sep 5Athletics @ Seattle MarinersPolymarket + DraftKings2.4%
- Sep 5New York Y @ San DiegoPolymarket + FanDuel27.5%
- Sep 5St. Louis @ ColoradoDraftKings + Kalshi2.7%
- Sep 4New York Y @ San DiegoPolymarket + BetRivers5.0%
- Sep 4New York Y @ San DiegoBetMGM + Kalshi4.1%
- Sep 4New York Y @ San DiegoPolymarket + Kalshi7.0%
- Sep 4New York Y @ San DiegoKalshi + FanDuel7.1%
- Sep 4Washington @ Los Angeles DKalshi + FanDuel0.8%
- Sep 4Athletics @ Seattle MarinersPolymarket + BetMGM1.5%
- Sep 4St. Louis @ ColoradoKalshi + BetRivers10.7%
- Sep 4Athletics @ Seattle MarinersPolymarket + DraftKings19.7%
- Sep 4New York Y @ San DiegoPolymarket + Kalshi3.5%
- Sep 4St. Louis @ ColoradoPolymarket + Kalshi109.1%
- Sep 4Athletics @ Seattle MarinersPolymarket + FanDuel5.8%
- Sep 4St. Louis @ ColoradoKalshi + FanDuel136.0%
- Sep 4New York Y @ San DiegoPolymarket + BetMGM2.5%
Every percentage is what the quoted prices implied at the moment we saw them, after fees and after the cost of your own order moving the book. Nobody placed these, and nothing already written is ever recalculated. The whole record across every sport is on the log.
Reading an MLB gap
A gap means backing one side on a prediction market and the other side at a sportsbook, splitting a stake between them so both outcomes pay back more than you put in. The percentage is what is left after Kalshi’s per-contract fee, Polymarket's 2%, and the price movement your own order causes, with the rounding running against the estimate.
It is an estimate from public prices at a moment in time, not a guarantee. A gap can close while you are placing the second order, and a half-filled pair is a one-sided bet rather than a hedge. The walkthrough runs the arithmetic end to end, and today’s live MLB board is on the front page.
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