Nearly $1.9 Billion Has Traded on the Midterms. How Close Will Kalshi and Polymarket Get?

Before the first Election Day votes were counted, traders had already put a price on who would control Congress. By late Monday, midterm contracts had generated nearly $1.9 billion in trading, according to a Washington Post analysis. Roughly $1.3 billion traded on Kalshi and $600 million on Polymarket.

By Tuesday morning, both exchanges put Democrats’ chances of taking the House at around 95%. The Senate left more room for a surprise. At 8:26 a.m. ET, MarketWatch reported 77% on Kalshi and 78% on Polymarket for Democratic control.

Texas and Michigan drew the money

Kalshi’s breakdown shows how unevenly that money was spread. Of $189.6 million traded on its individual Senate races in a pre-election snapshot, Texas accounted for $69.1 million and Michigan for $22.3 million. Between them, those two races represented about 48% of the total.

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Those dollars measure how often contracts changed hands. A trader can buy a contract on Monday and sell it on Tuesday, adding to volume both times. That makes volume a good guide to which races held traders’ attention. The price tells you which candidate they favored.

Take a Senate contract trading at 77 cents. A buyer who holds it to the result receives $1 if Democrats win control and zero if they fall short. The price implies roughly a three-in-four chance of winning. A voter survey asks people whom they plan to vote for.

One endorsement put Michigan’s odds to the test

On Sunday, Michigan Democratic Rep. Haley Stevens endorsed Republican Mike Rogers over Abdul El-Sayed, who had defeated her in the Democratic Senate primary. On PredictIt, El-Sayed’s contract briefly fell to 66 cents. By Monday morning, it had climbed back to 79 cents. Anyone who looked only at the closing price would have missed the market’s first reaction.

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What to watch as votes come in

Democrats need a net gain of four Senate seats. Texas offers a chance to pick one up. In Michigan, they’re defending a seat they already hold. That difference makes the two races worth watching together. A Democratic win in Texas would add to the party’s total, while a loss in Michigan would erase that gain.

Tonight also puts a fast-growing business in the spotlight. As Blockster reported last week, Robinhood earned $173 million from prediction markets last quarter, surpassing the $120 million it earned from crypto trading. Election contracts now sit alongside stocks and crypto in a familiar brokerage app.

“But how accurate the price is for any specific market is impossible to know.”

— Joshua Clinton, Vanderbilt University political scientist, speaking to Reuters

Keep the morning odds handy when returns start coming in. A jump from 77 cents to 90 cents after a county reports tells you what traders learned from those votes. The 77-cent price is the one to look back on if you want to know what they saw coming.