The open interest in prediction markets surged to an unprecedented $1.48 billion for the week ending June 15, marking the second consecutive week of record highs. This growth is largely attributed to an increase in sports-related contracts, which significantly boosted trading activities. Additionally, the weekly trading volume reached an impressive $10.8 billion, setting another all-time record for the industry.
According to a16z crypto, open interest—representing the value of active contracts in the market—has seen a remarkable sixfold increase over the past year. This metric indicates the capital that traders are willing to keep at risk, rather than reflecting settled contracts.
A16z commented, “The recent surge signifies a sixfold rise in the last year, showcasing how users are opting for longer-term financial positions and how prediction markets are evolving into robust market infrastructures.”
The record open interest was primarily driven by major platforms such as Kalshi and Polymarket, while smaller sites like Opinion, Limitless, and Myriad contributed a smaller portion of the overall activity.
Moreover, the growth was not limited to open interest alone. The weekly notional volume reached a staggering $12.2 billion, and fees from prediction market platforms soared to an all-time high of $76.8 million. The number of active users also peaked at 426,975 during this period.
Sports contracts emerged as the leading force in trading activity, accounting for $5.8 billion in notional volume—almost half of the total market trading. This category was the primary source of volume for both Kalshi and Polymarket.
The ongoing 2026 FIFA World Cup has played a significant role in boosting participation, drawing in new users and increasing trading activity. Reports indicate that some traders placed wagers in the seven-figure range on individual matches, with one trader reportedly earning $9.24 million in profits in a single day.
Additional market data revealed that prediction markets recorded $10.8 billion in weekly trading volume for the week ending June 15, marking yet another all-time high for the sector.
This increase represents a notable acceleration compared to the previous year, when a typical week in prediction markets generated around $500 million in trading volume, with even the busiest weeks falling short of $1 billion.
Industry analysts attribute this latest surge in activity to a mix of high-profile global events, including the SpaceX IPO, a U.S.-Iran peace agreement, the NBA Finals, the Stanley Cup Finals, and the initial stages of the FIFA World Cup.
The data indicates that prediction markets are appealing to a wider audience beyond traditional political forecasting, with traders increasingly engaging in markets linked to sports, economics, culture, and cryptocurrency events.