Midterm prediction markets near $1bn as CFTC pushes swaps rule
Trading on the 2026 US midterms is surging on Kalshi and Polymarket, while the NBA tightens prop betting rules and the CFTC advances a contested swaps proposal.
Notional volume traded on 2026 US midterm contracts had passed $750 million by 15 October, according to figures cited by CNN and reported by iGaming Business, a near eightfold jump on the roughly $92.4 million wagered on congressional and state races during the 2024 cycle.
The Anti-Corruption Data Collective counts more than 21,000 separate midterm offerings now live across Kalshi and Polymarket, and the nonprofit research group has estimated that total trading on the races could reach $1.6 billion once voting concludes.
The growth follows what Polymarket chief executive Shayne Coplan has described as a turning point for the sector: the platform's pricing of Donald Trump at around 58% as polls closed in 2024, against networks including NBC News that called the race a dead heat. Coplan told the Netflix documentary Instadoc: The Prediction Games that the episode gave prediction markets a new level of credibility, while author James Surowiecki said on the same programme that the midterms represent one of the industry's biggest tests to date.
Separately, the NBA and its official sportsbook partners agreed on Friday to restrict a category of player prop bets, a move the league framed as protecting market integrity ahead of next week's season opener, when the New York Knicks raise a championship banner. The sport has been contending with prop-manipulation allegations involving several former players due to stand trial in coming months.
Under the new rules, sportsbook partners will not offer individual-stat props on reserve players expected to play fewer than 12 minutes, and customers will no longer be able to combine multiple 'under' bets on a single player's statistics in one wager, a restriction aimed at parlays such as a combined under on points, rebounds and assists.
Those limits do not extend to Polymarket, where a three-leg combination betting under on LeBron James's points, rebounds and assists for his debut with the Philadelphia 76ers was still available, carrying a $14.19 payout on a $10 stake as of Friday night. Kalshi had not listed under-combination markets for NBA games by the same point. NBA executive vice president Scott Kaufman-Ross told ESPN that enforcing such prop restrictions remains difficult in the absence of a formal agreement with the US Commodity Futures Trading Commission.
On the regulatory front, the CFTC issued a Notice of Proposed Rulemaking on 9 October that would broaden the definition of financial swaps to encompass sports and political event contracts, reinforcing the agency's position that it holds exclusive federal jurisdiction over the products. That stance is contested by a majority of state attorneys general, and several appellate courts have already declined to find that sports derivatives preempt state gambling law, setting up a possible Supreme Court fight.
CFTC Chair Michael Selig, in his first interview since the proposal's release, told Fox Business on 15 October that the Commission's priority is curbing manipulation on commodity markets, including insider trading, wash trading and fraud. 'We regulate these in our derivatives markets every day, whether it's oil or any type of commodity,' he said, adding, 'My concern is that you can't offer an order book in a casino.'
The comments came in the same week Bloomberg reported that the CFTC and the Justice Department had opened a probe into $2.6 billion in suspiciously timed oil trades placed around the start of the US-Iran conflict, and after the Wall Street Journal reported last month that the agency had examined roughly $5 billion in Kalshi trading tied to bitcoin perpetual futures. Kalshi has denied any wash-trading allegations on its platform.