Prediction markets give Democrats strong odds of winning Congress

As polls closed in the US midterm elections, prediction markets showed rising expectations of Democratic gains in Congress.

Around midnight GMT on Wednesday, traders gave Democrats a 98% chance of winning the House and about an 80% chance of winning the Senate.

The odds shifted during the day, briefly putting the Democrats’ chance of taking the Senate at 88%.

More than $1.48 billion was wagered on the congressional elections across the markets cited, including Kalshi and Polymarket.

The platforms became more widely known after their 2024 forecasts pointed to Donald Trump winning the presidency, but past errors show they can get predictions wrong.

The election is a major test of the markets’ reliability and safeguards, and a result far from their forecasts could damage their reputation.