As Election Day kicks into high gear, traders are heading to popular platforms to put their predictions—and money—on the line in key Senate, House, and gubernatorial races across the United States. On Kalshi, they’re leaning blue, giving Democrats a 93% chance of winning control of the House and a 73% chance of taking the Senate.
The site’s midterm forecasts are catnip for political junkies, but are also translating into big dollars: Kalshi’s midterm-related trading volume has surpassed $1.4 billion as of Tuesday, according to data supplied to Fortune. Leading the pack is a contract on whether Republicans or Democrats will control Congress, which has drawn $251 million in trading volume. A similar contract on which party will control the House has crossed the $181 million mark in trading volume. A separate market tracking all four possible combinations of House and Senate control has topped $112 million.
Closely watched races are also drawing action on these platforms, where traders can wager on everything from sports to politics. The Los Angeles mayoral race, which will decide whether Democrat Karen Bass gets a second term, has drawn just shy of $110 million in trading volume. Texas’ Senate race is also picking up steam, nearing the $100 million mark, with traders giving Democrat James Talarico a 71% chance of defeating Republican Ken Paxton. But the blue bets only go so far in Texas, where traders give incumbent Republican Greg Abbott a 65% chance of winning a gubernatorial contest that has drawn $21 million in trading volume. His challenger, Gina Hinojosa, is seeking to give Texas its first Democratic governor since 1995.
The surge in midterm trading builds on prediction markets’ breakout moment in 2024, when traders on popular platforms Kalshi and Polymarket favored Donald Trump as the winning candidate even as polls largely showed a toss-up. His victory helped turn the platforms into closely watched political barometers.
But their forecasting record has hit a few bumps, with recent misses raising questions about how much faith to put in the odds.
Last month, traders on Kalshi and Polymarket put their money on Flávio Bolsonaro, the son of former Brazilian President Jair Bolsonaro, to unseat incumbent Lula da Silva. They gave Bolsonaro roughly an 80% chance of winning the presidential runoff—before the odds swung toward Lula as the results rolled in.
Wisconsin’s Democratic gubernatorial primary delivered another curveball in August, when traders gave Francesca Hong roughly a 95% chance of winning. Instead, David Crowley edged her out by less than half a percentage point. Polymarket later deleted a celebratory post touting Hong’s odds, while Kalshi’s founders defended the forecast with a reminder: “5% is not 0%.”
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