US Election Trading on Kalshi and Polymarket Jumps 153% to $104M Ahead of the Midterms - DeFi Rate
Election trading volume reached nearly $104 million across four prediction markets in the first 20 days of October, with Texas Senate and control of the House accounting for much of the increase.
Trading volume on the 2026 midterm elections reached $103.87 million across Kalshi, Polymarket US, ForecastEx and Gemini during the first 20 days of October, up from approximately $41 million over the same period in September. The surge wasn't spread evenly across the November ballot, with the Texas Senate race and the battle for control of the House emerging as the two biggest draws.
Texas Senate emerges as October's biggest growth market
Texas Senate generated $17.94 million in October trading volume on Kalshi, compared with $5.96 million during the full month of September. The first 20 days of October have already produced three times September's entire trading volume for the race. On Polymarket US, Texas Senate reached another $3.69 million in October volume, compared with $1.11 million during September.
The race between Republican Ken Paxton and Democrat James Talarico has attracted far more activity than most other individual Senate contests.
Control of the House attracts another $27 million
The national House-control market generated $26.98 million across the four operators during the first 20 days of October, putting it ahead of any individual state election. Kalshi accounted for $22.33 million, while Polymarket US recorded $4.03 million. House-control contracts allow traders to speculate on which party will hold the chamber after all 435 districts have voted, rather than requiring positions in individual congressional contests.
Iowa's races show growth beyond top markets
Outside Texas and national congressional-control markets, Iowa stands out for growth in October trading. Polymarket US recorded $1.44 million on Iowa's gubernatorial election in the first 20 days of October, compared with $296,475 in all of September. Iowa's Senate race is drawing more attention, with Polymarket US recording $1.28 million in October volume, while Kalshi generated another $2.20 million.
Not every election market is growing
October's gains have not been uniform, even among established election products. Kalshi's Ohio Senate market generated $2.49 million in the first 20 days of October, below the $2.71 million recorded across the full month of September. Other markets showed outright declines, with Polymarket US recording $695,028 on California's gubernatorial election in October, down from $1.06 million in September.
The broader figures remain heavily weighted toward Kalshi, which generated $79 million, representing approximately 76% of the four-operator October total, while Polymarket US accounted for $23.72 million. Polymarket US, however, posted the larger percentage increase, with election trading volume up 203% from the first 20 days of September. Kalshi recorded a 142% increase.
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