Prediction Markets Hit Record Volume as May Trading Reaches $28.4 Billion

Prediction markets reached a trading record in May as total volume rose to $28.4 billion, according to Artemis data

ContentsKalshi Takes a Larger ShareRegulation Shapes the MarketFour-Month Streak Signals GrowthThe figure surpassed January’s previous peak of $27.1 billion and extended the sector’s growth streak to four straight months

The increase came without a major election-style catalyst, which suggests that prediction market activity is moving from event-driven bursts toward steadier daily participation.

The May total showed that users are returning to these platforms for more than occasional political content. Trading depth has improved across sports, crypto, macro, and news-linked outcomes.

Kalshi Takes a Larger Share

Kalshi recorded $17.3 billion in May volume, setting its own monthly high. The figure marked a 29% increase from April and gave the platform about 61% of total sector volume.

Polymarket followed with $8.4 billion in monthly trading. Together, Kalshi and Polymarket accounted for close to 90% of all prediction market activity in May, which shows that the sector remains heavily concentrated around two leading venues.

The current split also reflects a major change from the previous year. Polymarket led the category through 2024 and maintained a clear lead until Kalshi overtook it in September 2025. Since then, Kalshi has continued to widen its share, especially in contracts tied to sports and crypto-related outcomes.

Regulation Shapes the Market

Kalshi’s growth has been helped by its regulated United States status. That position has supported its sports markets, which now drive most of its trading volume and give it a wider base of domestic users.

Polymarket has faced more regulatory pressure in recent months, and that has slowed its expansion. Its volume has not collapsed, but its growth has lost momentum while Kalshi has continued to climb.

The regulatory picture remains important for the next stage of the market. The CFTC has indicated that clearer prediction market guidance is ahead, and that could support licensed platforms. Polymarket has also moved to re-enter the United States market by buying a CFTC-licensed venue.

Four-Month Streak Signals Growth

The record itself matters, but the four-month rise may be more important. A single strong month can come from one election, one viral contract, or one sports cycle. A steady streak shows that more users are treating prediction markets as regular trading venues.

The sector is also gaining attention beyond retail users. Newsrooms now cite market odds, hedge funds monitor them, and market makers such as Wintermute quote prices across leading venues.

New builders may add another layer. Hyperliquid launched HIP 4 outcome contracts on mainnet on May 2, allowing developers to deploy markets on chain. Its early volume was around $87.7 million, but the model points to broader market creation ahead.