The election last night was clearly a victory for Democrats. But was it a surprise? For the most part, no, especially if you follow prediction markets. Here’s what the Senate map looked like on ElectionBettingOdds.com the night before the election:
Of course, there are still a few surprises on that map, such as Iowa, South Carolina, and maybe Mississippi. But only Mississippi was a huge surprise. Betting markets had Iowa as a toss-up, and South Carolina as 2/1. And even in Mississippi, the Democrat had 1-in-7 chances based on the average across three betting markets. 1-in-7 chances do happen sometimes! None of the states that were solid blue or red on the map (indicating >90% chances) went the other way. But even without those three races, it was clear that Democrats were the favorite (even if the extent of their domination wasn’t completely clear the day before).
And these are not just a few cherry-picked results from one election. A recent paper published in PNAS shows that across a wide variety of outcomes, prediction markets are “well calibrated” — that is, events with X% probability on prediction markets tend to happen… about X% of the time!
UPDATE: Here’s a calibration Kalshi just provided for the 2026 midterms:
