What prediction markets told us about the midterm election
Both Kalshi and Polymarket were quick to celebrate big wins on midterm election night, touting what they say was accurate forecasting.
With billions waged on these prediction markets, which allowed traders to bet on candidate victories and control of the Senate and House, their accuracy was pushed into the spotlight. Media companies such as CNN and MSNBC shared prediction-market odds in their midterm coverage, while rappers such as YG and actors such as Heidi Montag weighed in on their midterm bets on election night.
According to Kalshi’s midterm election recap, $2.5 billion US was traded on midterm markets, nearly double the $1.3 billion US reported during the 2024 election cycle. Polymarket recorded nearly $700 million US in wagers during this election cycle across its U.S. and international platforms, according to Reuters.
Polymarket said on X that the prediction-market platform was “right” and claimed that “98.4 per cent of resolved midterm races went to the Polymarket favorite the day before Election Day.”
Kalshi made a similar claim, saying candidates favoured on its platform won or lead 98 per cent of races before polls closed on election day.
Valerie Cross, head of emerging verticals at NEXTPredict.io, which monitored Kalshi and Polymarket on election night, said that while those figures aren’t necessarily wrong, “it’s easy to overread.”
She added that the figures reflect how prediction markets were able to incorporate “early returns, exit polls and county counts quickly, and mostly moved in the right direction.”
“They were also early to flag upsets, because raw vote counts can make a race look closer than the odds imply,” she said.
Kalshi and Polymarket election prediction markets are seeing record trades ahead of the 2026 U.S. midterms. For The National, CBC’s Ashley Fraser explores how betting odds can influence American voters and if the platforms risk distorting public perception.
Predicting a blue tsunami
But while the platforms might have been mostly accurate about who would win, they didn’t predict some of the most surprising races of the night.
An analysis by Betting Intelligence of more than 400 races identified 14 upsets, all won by Democrats.
One was the South Carolina Senate race, where prediction markets had favoured Republican candidate Darline Graham to win, giving her about a 70 per cent chance before Democrat Annie Andrews unexpectedly won.
Other upsets included Democrat Gina Hinojosa’s victory over incumbent Republican Gov. Greg Abbott in Texas. Markets had put Hinojosa’s chances at 40.1 per cent the day before the election.
The firm concluded that both polls and markets “identified the eventual winner equally often, and both underestimated Democratic candidates.”
David Szakyoni, co-founder of the Anti-Corruption Data Collective, which analyzes…
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