On Election Day, market prices and statistical forecasts both favored Democrats to control the U.S. House and Senate, but a Yahoo Finance analysis found the models assigned the party higher odds in both chambers.
Published at 9:43 a.m. EST Nov. 3, the analysis put Democrats’ House chances at 94% in a three-market average and 96.2% in the average of two forecasts. For the Senate, it reported 77.3% from markets and 80.2% from models, a 2.9-percentage-point spread. The percentages describe chances of controlling each chamber, not vote shares.
Yahoo’s market measure combined daily prices from Kalshi, Polymarket and PredictIt. Its comparison set averaged forecasts from statistician Nate Silver and Harvard’s ElectIt project. Yahoo reported that the Senate gap averaged about 7.3 percentage points from Sept. 1 onward, compared with 2.9 points on Tuesday. The House gap averaged less than one point in recent months, then measured 2.2 points in Tuesday’s comparison.
Kalshi’s Nov. 2 snapshot, based on prices at about 2:11 p.m. ET, gave Democrats a 94.1% chance of House control and a 75% chance in the Senate. Those figures came from one platform the day before Yahoo’s three-market average.
ElectIt offers a post-nomination forecast without polls, another that includes national generic-ballot polling, and a third that also uses district and state polls. Yahoo Finance did not specify which version it included.
Yahoo Finance also cited 2024 forecasts: markets gave then-candidate Donald Trump a 57% to 62% chance of winning the day before voting, while Silver’s Election Day model gave then-Vice President Kamala Harris a 50.015% chance.
Yahoo Finance reported that Kalshi and Polymarket argue traders who risk money have an incentive to make accurate forecasts. A Senate Banking Committee release said Sen. Elizabeth Warren and Sen. John Curtis asked the platforms about safeguards against insider trading, manipulation and bets based on material nonpublic information. They said election contracts can receive prominent coverage and be treated by some observers as signs of political momentum. The letter raised concerns but did not establish that the midterm odds in Yahoo’s comparison had been manipulated.
The Nov. 3 vote and the race calls that follow are the next indicators for the forecasts.
