Kalshi and the 2026 Midterms: Calibration and Accuracy

A study released earlier this year assessed over 2.2 million Kalshi markets over the history of the Exchange and found them to be both well-calibrated and accurate (Kagan and Baiocchi, 2026). In this study, we apply a similar analytical lens to markets in the 2026 U.S. Midterm elections. Using data from Kalshi’s Exchange and that sourced from alternative election model projections, we find that for races called by 6:26 a.m. ET on November 4, 2026, directional market accuracy improved from 93.8% (3 months out) to 98.2% (polls close), and Brier scores fell from 0.040 to 0.016. Further, Kalshi matched or exceeded polling averages at every horizon where they existed, and on the 9 a.m. Election Day snapshot recorded the lowest Brier score of all forecasts compared.