Polymarket built a $14 billion US trading business almost entirely on sports bets

Polymarket's US prediction exchange recorded about $13.7 billion in contract-face-value trading in the 30 days through Oct. 26, with sports accounting for 98.2% of that turnover, according to DeFi Rate's data.That concentration leaves its American expansion heavily exposed to the dispute over whether sports event contracts fall under federal derivatives oversight or state gambling laws.The figures coincide with Reuters' Oct. 27 report that the Commodity Futures Trading Commission (CFTC) is again examining compliance with Polymarket's 2022 settlement restricting US access to its offshore platform.The report also examined onboarding and customer protections at the newer US exchange, citing two people familiar with the matter.Alongside these questions sits a broader fight over who regulates prediction markets, as the CFTC announced Oct. 27 that it had sued Utah, adding to proceedings against nine other states.Two measures of Polymarket's expansionIn a measurement from Sept. 27 to Oct. 26, DeFi Rate puts Polymarket US's face-value turnover up 78% from the preceding 30 days, with sports supplying about $13.5 billion of the latest total.The dataset counts each contract at its $1 face val...