Kalshi midterm trading volume exceeds $2.5 billion

Kalshi’s initial tally said market favorites won 479 of 487 races resolved by 6 a.m. ET on Nov. 4, an approximate success rate of 98.4%, rounded to 98% in its announcement. The count included House, Senate and gubernatorial contests, as well as races for attorney general, lieutenant governor and secretary of state. Several races, including Senate contests in Alaska and Mississippi, were still unresolved when the tally was published.

The company reported that favorites won 356 of 360 House races, 32 of 33 Senate contests and 33 of 34 gubernatorial elections. Kalshi also said its market for control of the House reached a 99% probability of a Democratic majority at 8:10 p.m. ET on election night; the Senate control market reached that mark at 9 p.m.

In live updates, the platform showed Democratic House control at 97.2% at 6:55 p.m. ET. By 8:06 p.m., Republican incumbent Greg Abbott was no longer favored in the Texas governor’s race. Kalshi later put James Talarico’s chance of winning the Texas Senate contest at 99% at 9:35 p.m., Annie Andrews’s chance in South Carolina at the same level at 10:10 p.m., and Texas gubernatorial challenger Gina Hinojosa at 99% at 11:35 p.m. The company described these as market projections, not official calls or contract settlements.

A separate Kalshi Research analysis found that directional accuracy for races called by 6:26 a.m. ET on Nov. 4 rose from 93.8% three months before voting to 98.2% when polls closed. Brier scores, which measure the distance between forecast probabilities and outcomes, dropped from 0.040 to 0.016; lower scores indicate better performance. The accompanying working paper by Nicole Kagan and Rubens Baiocchi cautioned that a count of winning favorites does not account for confidence: a correct forecast priced at 51% scores the same directionally as one at 95%.

Reuters reported that markets anticipated Democratic control of Congress but underestimated some candidates’ gains. BETINT, cited in that coverage, counted 14 Democratic winners who had been market underdogs a week earlier and found that markets and polls performed roughly equally well overall.