The World Cup pushed volumes to records, and regulators want to see who keeps their footing
Kalshi handled more than US$31bn in notional volume in June, a jump of more than 70 percent from May's US$17.9bn, according to user-collected data on Dune Analytics cited by CNBC.
The surge, driven by the FIFA World Cup, pushed prediction markets toward what the Financial Times reported could become the largest market in history, more than a month before the final.
Kalshi has cleared more than US$1bn in daily volume every day since the tournament began on June 11, CNBC reported.
Rival Polymarket set a monthly record on its international event-contract exchange, where notional trading topped US$10.8bn and reversed declines recorded in April and May.
On Polymarket's US platform, volume reached more than US$3.5bn, up from US$1.77bn a month earlier.
The activity extended to newer entrants.
Rothera, a joint venture between Susquehanna International Group and Robinhood, recorded US$2bn in notional volume in its debut month and now accounts for 7 percent of US prediction-market activity, according to Bank of America.
Rothera launched in June, when Robinhood began routing certain World Cup contracts from its brokerage to the platform, as per CNBC.
How the platforms manage the surge may indicate how they handle other contract markets, CNBC reported, at a moment when regulators and institutions are assessing their performance.
The World Cup will test whether prediction markets can keep a level playing field for investors through a sustained, high-volume period, said Asaf Meir, chief executive of Solidus Labs.
He called it "a huge pressure test" in comments to CNBC, noting his market-integrity firm partners with Kalshi.
The platforms operate under US Commodity Futures Trading Commission oversight and have used a self-certification process to introduce new soccer wagers, the Financial Times reported.
Polymarket faces scrutiny over market manipulation: in April, a bettor allegedly interfered with temperature gauges at Paris-Charles de Gaulle airport to swing a wager, and US prosecutors are pursuing insider-trading cases tied to the platform.
Trading volume has not always tracked conviction.
Ahead of the tournament, Uzbekistan drew the most betting on Polymarket's winner market, with volume exceeding US$58m despite odds of roughly 0.01 percent, the FT reported, largely because the platform rewards users who provide liquidity.
Most traders had already closed their positions.
Pricing also diverges across sources.
With 16 teams remaining, a Forbes analysis found that FIFA rankings, sportsbook odds and prediction-market prices assign different probabilities to the same outcome.
Its rankings-based model gave France a 24.5 percent chance of winning, against 31.5 percent in sportsbook odds and 34.1 percent in prediction markets, while Argentina drew 25.2 percent in the model but about 16 percent across both markets.
In Canada, operators reported sharp increases in activity.
BetMGM said bets placed per match in Canada rose 71 percent and handle, the total amount wagered, climbed 73 percent this World Cup compared with the 2022 tournament in Qatar, its chief revenue officer, Matt Prevost, told CBC News.
Across all venues worldwide, Macquarie estimated World Cup betting could exceed US$50bn this year, a 43 percent increase on 2022, as reported by the FT.
Canadian regulators are weighing tighter rules.
In April, members of Parliament voted to send the National Framework on Sports Betting Advertising Act to the Standing Committee on Canadian Heritage, CBC News reported; if passed, it would require national rules on where and how often sports-betting ads appear.
Alberta will open its market to private operators on July 13 with responsible-gaming requirements, and Ontario has signalled changes to its advertising rules.
The expansion has coincided with rising harm indicators.
Ontario recorded an increase in problem-gambling helpline calls after it legalized private online gambling in 2022, according to CBC News.
"What's really lacking in Canada is an overarching or governing set of regulations from coast to coast to coast that address advertising specifically for gambling," Spencer Murch, a cognitive psychologist at the University of Calgary, told CBC News.
