Kalshi and Polymarket Help Push Weekly Volume to $14.4B

Prediction markets have reached another weekly record. New a16z crypto data shows faster trading growth, deeper open interest and a wider mix of contracts beyond sport.

Weekly prediction-market volume reached $14.4 billion last week, according to the numbers reported by a16z crypto. It was the first time the sector crossed that level.

The pace of growth has accelerated sharply in 2026. At the beginning of the year, the volume stood at about $5-$6 billion per week. The previous record week saw the market set a new high of roughly $10 billion.

Open Interest Adds Weight to the Growth

Trading volume measures how much value moved through prediction markets during the week. The next signal comes from open interest, which tracks capital tied up in active, unresolved positions.

Open interest has also hit a new high. According to a16z, open interest in the prediction market went up to $1.6 billion last week. This is now the third consecutive weekly record for open interest.

This is significant because the growth in open interest takes place when the pace of opening new positions exceeds the pace of settling older positions. In simpler terms, traders are keeping more money exposed in their event contracts, instead of using the platforms only for short-term event trades.

Sports Contracts Still Drive Liquidity

Sports contracts remain a major liquidity driver, especially during the World Cup period. The tournament has added liquidity to short-duration markets linked to match and tournament outcomes.

That sports base gives prediction exchanges regular traffic and repeat use. It also makes the product easier to understand for casual users, even if the product is framed differently.

For market operators, affiliates, and market observers, this is where the betting comparison becomes impossible to avoid. The trading behavior may appear very similar to gambling activity.

The sharpest shift is outside sports. According to a16z, combined weekly volume on Kalshi and Polymarket in non-sport markets amounts to $3.6 billion. It includes markets tied to politics, economics, geopolitics, and current events.

A year ago, the entire prediction market segment was smaller than this number, even with sports included. The volume of non-sports markets has increased substantially since July 2025, when weekly volume in such markets was around $200 million.

On Kalshi, longer-tail markets now account for more than 20% of trading volume. It indicates an application beyond betting on a single match or election results.

Market Read

This record does not settle how prediction markets should be classified. It does make them harder for gambling, financial and media regulators to ignore. Liquidity is now large enough to draw attention from partners, trading firms, and consumer platforms.

For iGaming businesses, the signal is clear. Event-based trading is becoming a rival attention channel around sport, politics and live news. The opportunity is real, but so is the compliance pressure. The next phase will likely depend on how platforms explain risk, monitor users and defend the line between financial contracts and betting products.