Kalshi, Polymarket volumes collapse after World Cup ends
Prediction market platforms Kalshi and Polymarket are experiencing a sharp liquidity contraction as the World Cup concludes, exposing their deep reliance on major sporting events to drive trading volume.
Spain's 1-0 victory over Argentina in the World Cup final on July 19 has triggered a rapid unwind across major prediction platforms. Combined open interest on Kalshi and Polymarket has dropped 20% from a roughly $2 billion peak reached in early July.
The decline in actual trading turnover is far steeper than the open interest contraction. Kalshi’s sports volume plummeted 55% from roughly $9 billion in the week ending July 5 to about $4 billion by July 19. Polymarket suffered a 70% crash over the same period, with sports volume falling from $2.3 billion to $740 million.
On a smoothed weekly basis, total open interest climbed from $1.2 billion in late May to nearly $1.8 billion in early July before retreating to $1.5 billion. Sports betting accounted for roughly 80% of total volume on both platforms throughout the tournament. The divergence between volume and open interest drops is driven by market mechanics: daily turnover collapses immediately when matches end, while open interest unwinds only as markets resolve.
Data compiled by DeFiOasis reveals a highly concentrated profit distribution among Polymarket users. Of the 194,000 addresses that traded the World Cup winner market, approximately two-thirds lost money. While most participants saw gains or losses under $100, 54 addresses made over $100,000—including five that cleared $1 million—and 43 lost more than $100,000.
The rapid liquidity drain stems directly from the tournament's structure. The group stage in June featured 48 teams, flooding the platforms with daily betting markets that vanished as the bracket narrowed. This extreme event-dependency presents a structural challenge for prediction market operators, which struggle to maintain engagement without a constant feed of macro-catalysts.
With the World Cup concluded, prediction market activity is expected to remain subdued compared to its summer peaks. Market participants will likely look toward the US midterm election cycle in the fall as the next potential injection of trading volume.
