In this photo illustration, Apps for online prediction market sites are shown on an electronic device on Feb. 25, 2026 in Chicago, Illinois. <\/p>\n
Scott Olson | Getty Images<\/p>\n
The 2026 FIFA World Cup<\/a> was forecast to be the biggest gambling event<\/a> in history. For prediction market<\/a> platforms, that’s led to soaring trading volumes in June.\u00a0<\/p>\n Kalshi<\/a> saw more than $31 billion in notional volume during the month, a more than 70% increase from May’s total of $17.9 billion<\/a>, according to user collected data on Dune Analytics. The platform has consistently managed volume over $1 billion daily since the soccer tournament began on June 11.\u00a0<\/p>\n Polymarket’s<\/a> international event contract exchange set a new record high in monthly volume, with notional trading exceeding $10.8 billion in June. That reverses a downtrend in April and May, when volume fell<\/a>.\u00a0<\/p>\n Meanwhile, Polymarket’s U.S. platform did north of $3.5 billion in notional volume during the month, up from $1.77 billion in May.\u00a0<\/p>\n Team USA Monday<\/p>\n Team USA is set to play Belgium in the round of 16 on Monday night. More than $64 million on Kalshi and $122 million on Polymarket has been traded on whether the U.S. will win the tournament, though odds of that happening are just 4.3% and 3%, respectively, on each platform.<\/p>\n World Cup enthusiasm has given a jolt to prediction market platform Rothera, a joint venture between Susquehanna International Group and Robinhood<\/a>. Rothera debuted in June, when Robinhood began routing certain World Cup contracts<\/a> on its brokerage to the platform.\u00a0<\/p>\n Rothera saw $2 billion in notional trading volume during the month, and now accounts for 7% of U.S. prediction market volume, according to Bank of America.\u00a0<\/p>\n All platforms leaned into the World Cup to boost traffic. Polymarket launched a competition to reward up to $2 million<\/a> to whoever can craft a perfect World Cup knockout round bracket. On the Apple app store, Kalshi boasted that users can “Trade the World Cup” in the title of its mobile platform.\u00a0<\/p>\n Heightened open interest \u2014 the total number of active, unsettled contracts on the platforms \u2014 may also reflect World Cup excitement. Kalshi open interest is now above $1 billion. Polymarket open interest is just under $400 million \u2014 elevated, but about where its international platform has been for the last few months.<\/p>\n Sports were the focus last month for event contract exchanges, but how the platforms handled the surge in volume may be a sign of how they manage other contract topics in the future.\u00a0<\/p>\n Asaf Meir, CEO at Solidus Labs \u2014 a market integrity company that has a partnership with Kalshi \u2014 said the World Cup is a key moment for platforms as both regulators<\/a> and institutions are eying how they perform.\u00a0<\/p>\n Outside observers are asking, “Is it safe enough? Is it mature enough? Does it have enough volume?,” Meir said. “The World Cup is such a huge pressure test to see whether indeed prediction markets are able to deliver their word on maintaining a level playing field for all investors for a long period of time in a sustained high-volume environment.”<\/p>\n Disclosure: CNBC and Kalshi have a commercial relationship that includes customer acquisition and a minority investment.<\/p>\n