Kalshi and Polymarket's Combined Trading Volume Jumps 75% to $45 Billion in June

Prediction market platforms just wrapped up their busiest month on record, and the World Cup deserves most of the credit. Kalshi, Polymarket, and Polymarket's US arm processed $44.8 billion in trading volume during June, a 75% increase from May's $25.66 billion, according to data compiled by The Block's market dashboard. 

Kalshi pulled ahead of its rivals by a wide margin. The platform's volume climbed 87.4% month over month, rising from $16.81 billion to $31.5 billion, making it the single largest contributor to the industry's overall growth. Polymarket's international platform also grew, taking in $10.26 billion for the month, up 45% from $7.08 billion in May. 

Polymarket's US-regulated arm showed the most consistent upward trajectory of the three. After Polymarket's non-US business slid steadily from March through May, its American platform kept climbing, bringing in $3.04 billion in June, well above the $1.77 billion it logged the prior month. 

The World Cup, which began on June 11 and runs through July 19, is widely seen as the driving force behind the surge in prediction market apps. Kalshi's market tied to the tournament's eventual champion alone has pulled in more than $832 million in wagers, with France drawing support from roughly 35% of bettors.  

Individual match contracts on Polymarket have also drawn heavy interest, with wagers on single games ranging from $500,000 to $2 million apiece. Meanwhile, more than a dozen states have filed legal action against Kalshi and Polymarket over their sports contracts, arguing the platforms are offering unlicensed gambling. 

World Cup trading turns into a record-setting stretch for Kalshi 

That question of who benefits from a market and who gets hurt by it takes on a very literal shape once the tournament in question is the World Cup. The event has turned Polymarket and Kalshi into something close to a running public ledger, with more than $5 billion traded across both platforms so far.  

That surge, layered on top of the NBA Finals happening around the same stretch, pushed Kalshi through its first three-day run of daily volume above $1 billion. 

Because these platforms operate in the open, individual bets and their outcomes are visible in a way traditional markets rarely allow. Over one recent seven-day span, 18 of Polymarket's 20 most profitable trades worldwide were tied to World Cup matches.  

A trader going by “GRIMDRIP” turned $6 million into $13.6 million across two wagers on a Czech Republic versus South Africa match, the platform's biggest World Cup win to date. Another account, “mintblade”, doubled a $7 million bet on Iran beating New Zealand, while a trader known as “endlessFate” collected $5.6 million on Saudi Arabia-Uruguay and $2.7 million on Colombia over Uzbekistan. 

The losses have been just as steep. “endlessFate” also lost $1.2 million on a mis-predicted US-Paraguay tie, and one trader dropped roughly $9 million betting against a Belgium and Egypt draw.