Prediction market monthly trading volume hit an all-time high of $28.4 billion in May. On June 1, blockchain media outlet Cryptopolitan reported the figure topped the previous record of $27.1 billion set in January this year, extending a fourth consecutive monthly rise in volume.

The record drew attention because it came without a clear major event. The January surge was influenced by lingering effects from the election cycle and start-of-year positioning, but May had no comparable catalyst. That has prompted interpretation that prediction markets are shifting away from event-driven spikes toward a market with regular, ongoing trading.

By platform, Kalshi recorded $17.3 billion in May, setting a new monthly high for itself. That was up 29 percent from the previous month and accounted for about 61 percent of total volume. Polymarket volume was $8.4 billion, and Kalshi was nearly double that. The combined share of the two platforms was close to 90 percent, keeping the market in a two-horse race.

As recently as a year ago, Polymarket held the market lead. It stayed ahead from 2024 through September 2025, but Kalshi began to pull ahead afterward. In cryptocurrency-related contracts tallied earlier this month, Kalshi's share has also risen steeply since February.

The reversal is seen as influenced by differences in the regulatory environment. Kalshi, which is regulated in the United States, is being driven mostly by its sports business in trading volume. Polymarket, by contrast, was blocked by regulatory barriers for much of the past quarter. Polymarket volume did not plunge from the previous month, but the gap widened as its growth stalled.

The market base is also widening. Newsrooms cite prediction probabilities, and hedge funds are watching them. Market makers such as Wintermute are posting two-way quotes on major platforms.

Regulatory and developer-ecosystem changes are also continuing. The U.S. Commodity Futures Trading Commission signaled it will make guidelines related to prediction markets clearer. Polymarket acquired a CFTC-licensed exchange to re-enter the U.S. market. On May 2, Hyperliquid activated HIP-4 outcome contracts on its mainnet. Initial trading was about $87.7 million, less than 1 percent of the market, but it showed the potential of a structure in which anyone can open a market and settle on-chain.