The Divergence Index
One number for how far Kalshi and Polymarket disagree right now: the volume-weighted average gap between YES prices on the same real-world event, measured across every matched cross-venue pair we track.
Updated 9:03 PM ET, Oct 11 · prices refresh four times daily
How to read it. A YES contract priced at 62¢ on Kalshi and 55¢ on Polymarket is a 7-point disagreement about the same future. The index averages those gaps across all 134 matched pairs, weighted by traded volume so a thin novelty market cannot move the number.
Near 0, the venues agree and prices are probably efficient. When the index climbs, one venue is being slow, one crowd is wrong, or news is landing unevenly: either way, that is where the interesting prices live. The pairs driving today's number are listed below, largest gap first.
Last 22 build days
Today's widest disagreements
| Matched event | Kalshi YES | Polymarket YES | Gap |
|---|---|---|---|
| an NL West team: Pro Baseball Championship: Winning league Kalshi vs Polymarket | 70¢ | 47¢ | 22.5pp |
| J.D. Vance: 2028 Republican presidential nominee Kalshi vs Polymarket | 42¢ | 48¢ | 5.9pp |
| Seattle Seahawks: NFC West Division Winner Kalshi vs Polymarket | 18¢ | 24¢ | 5.5pp |
| Chiang Wan-an: Taipei mayoral election winner Kalshi vs Polymarket | 62¢ | 66¢ | 4.5pp |
| Alexandria Ocasio-Cortez: 2028 Democratic presidential nominee Kalshi vs Polymarket | 13¢ | 17¢ | 4.2pp |
| François Hollande: Next French presidential election winner Kalshi vs Polymarket | 7¢ | 3¢ | 4.2pp |
| Nelly Dever: Kamloops mayoral election winner Kalshi vs Polymarket | 22¢ | 26¢ | 3.9pp |
| Monaco: Ligue 1 Champion Kalshi vs Polymarket | 8¢ | 4¢ | 3.8pp |
| Édouard Philippe: Next French presidential election winner Kalshi vs Polymarket | 20¢ | 23¢ | 3.0pp |
| Olivia Chow: Toronto mayoral election winner Kalshi vs Polymarket | 67¢ | 70¢ | 3.0pp |
| Nashville SC: MLS Eastern Conference Champion Kalshi vs Polymarket | 56¢ | 59¢ | 3.0pp |
| Los Angeles Dodgers: Pro Baseball Champion Kalshi vs Polymarket | 49¢ | 46¢ | 2.8pp |
| Marine Le Pen: Next French presidential election winner Kalshi vs Polymarket | 42¢ | 39¢ | 2.5pp |
| KT Rolster: Demacia Cup Global Invitational Champion Kalshi vs Polymarket | 48¢ | 46¢ | 2.5pp |
| Napoli: Serie A Champion Kalshi vs Polymarket | 4¢ | 1¢ | 2.1pp |
| Manchester City: English Premier League Champion Kalshi vs Polymarket | 21¢ | 19¢ | 2.0pp |
| Arsenal: English Premier League Champion Kalshi vs Polymarket | 60¢ | 62¢ | 2.0pp |
| Pittsburgh Steelers: AFC North Division Winner Kalshi vs Polymarket | 9¢ | 11¢ | 2.0pp |
| Gavin Newsom: 2028 Democratic presidential nominee Kalshi vs Polymarket | 13¢ | 15¢ | 1.9pp |
| Jonathan Kreiss-Tomkins: Alaska Governor winner Kalshi vs Polymarket | 76¢ | 78¢ | 1.9pp |
| Cleveland Guardians: Pro Baseball Champion Kalshi vs Polymarket | 10¢ | 8¢ | 1.9pp |
| Andy Beshear: 2028 Democratic presidential nominee Kalshi vs Polymarket | 5¢ | 3¢ | 1.7pp |
| Detroit Pistons: 2027 Pro Basketball Champion Kalshi vs Polymarket | 1¢ | 3¢ | 1.7pp |
| Ron DeSantis: 2028 Republican presidential nominee Kalshi vs Polymarket | 4¢ | 2¢ | 1.6pp |
| Bernie Sanders: 2028 Democratic presidential nominee Kalshi vs Polymarket | 0¢ | 1¢ | 1.5pp |
Methodology
1. A pair counts only when we can check that both exchanges are asking the same question. Polymarket has to ask whether a named person or team will win a named contest, and Kalshi has to list a who-wins event for that contest and year with exactly one open market carrying that name. Pairs with a bid and ask more than 10 cents apart, contests ending within three days, and midpoint gaps over 25 points are dropped. The full rules are on the cross-listed pairs page.
2. For each pair we take the absolute difference between the two midpoints (halfway between bid and ask), in points. Pairs that agree stay in the average, so the index reads low when the exchanges agree.
3. The index is the volume-weighted mean of those gaps, where each pair's weight is the combined traded volume of both markets. It is recomputed at every site build from the same live data that powers the markets table, and the daily closing value is archived to build the history above.
The index is a measurement, not advice. A wide gap can be a real mispricing, a difference in contract wording, or a settlement-rule mismatch; read both contracts before trading either side. See also cross-listed pairs and the biggest price moves.