The 2026 FIFA World Cup was originally predicted to be the biggest betting event in history. For prediction market platforms, this directly led to a surge in trading volume in June. According to user-collected data from Dune Analytics, the Kalshi platform’s notional trading volume exceeded $31 billion that month, a significant increase of more than 70% from $17.9 billion in May. Since the start of the football championship on June 11, the platform’s daily trading volume has remained stable above $1 billion.
Polymarket’s international active contracts exchange has hit an all-time high in monthly trading volumes, with notional trading volume exceeding $10.8 billion in June. This also reverses the downward trend in transaction volume in April and May this year.
Meanwhile, Polymarket's U.S. platform's notional trading volume exceeded $3.5 billion for the month, a sharp increase from May's $1.77 billion.
The United States will face Belgium on Monday night. At present, on Kalshi and Polymarket, the contract transaction volume on "whether the United States team can win this World Cup" has exceeded US$64 million and US$122 million respectively. However, on these two platforms, the probability of the US team winning the championship is only 4.3% and 3% respectively.
The craze of the World Cup has also given a boost to the prediction market platform Rothera. Rothera, a joint venture between Susquehanna International Group and Robinhood, debuted in June. At that time, Robinhood began routing some World Cup contracts in its brokerage business to the platform.
According to Bank of America data, Rothera’s nominal trading volume reached US$2 billion that month and currently accounts for 7% of the US forecast market’s trading share.
Major platforms have taken advantage of the World Cup to drive traffic. Polymarket has launched a competition offering up to $2 million in prizes to participants who can accurately predict the perfect matchup for the World Cup knockout rounds. In the Apple App Store, Kalshi even put the slogan "Trade the World Cup" directly in the title of the mobile platform.
The significant increase in open interest (that is, the total number of active and unsettled contracts on the platform) also reflects people's enthusiasm for the World Cup. Currently, Kalshi’s open interest exceeds US$1 billion; Polymarket’s open interest is close to US$400 million. Although it has increased, it is roughly the same as the level of its international platform in the past few months.
Last month, sports events were the absolute focus of these event contract exchanges. But how platforms handle this surge in trading volume may be an indication of how they perform on other contract topics in the future.
Asaf Meir, CEO of SolidusLabs, a market integrity company that works with Kalshi, said the World Cup is a critical moment for major platforms, as regulators and related agencies are closely watching their performance.
The outside world is looking at: "Is the platform secure enough? Is it mature enough? Is the transaction volume sufficient?" Meir said, "The World Cup is a huge stress test, designed to test whether the prediction market can really fulfill its promise and maintain a fair gaming environment for all investors in the long term in a sustained high transaction volume environment."