Prediction market open interest climbed to a record $1.48 billion in the week ending June 15, roughly a sixfold increase over the past year.
Open interest was not the only milestone. Notional volume, weekly fees, and active users all hit new highs as the FIFA World Cup pushed sports betting sharply higher.
Prediction Markets Notch All-Time High With Sixfold Open Interest Surge
According to a16z crypto, it was the second consecutive weekly peak. Kalshi and Polymarket account for most of the figure. Smaller venues such as Opinion, Limitless, and Myriad trail well behind.
The post explained that, unlike trading volume, which measures daily churn, open interest tracks the capital that participants keep deployed and at risk. The sustained climb shows traders holding longer-term positions across politics, economics, culture, and crypto.
“The recent surge represents a roughly sixfold increase over the past year, highlighting how users are maintaining longer-term financial positions and how prediction markets are maturing into durable market infrastructure,” a16z wrote.
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Sports Event Contracts Fuel the Climb
The growth extended beyond open interest. Dune data showed weekly fees reached a record $76.8 million, while active users climbed to an all-time high of 426,975.
Sports became the dominant force behind the latest surge. Total notional volume across prediction markets hit a record $12.2 billion during the week.
Notably, sports-related markets account for $5.8 billion, nearly half of the total. The segment was the largest volume driver on both Polymarket and Kalshi.
The ongoing 2026 FIFA World Cup has played a key role in attracting new participants to these platforms. Betting activity has intensified significantly, with some users placing seven-figure wagers on individual matches. In one notable case, a trader reportedly generated $9.24 million in profits in a single day.
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