Kalshi & Polymarket Dominate Prediction Markets With ~99% Share

Prediction markets are entering a rapid growth phase. Industry forecasts suggest total volume could surge ~400%, from roughly $9B in 2024 to $40B in 2025, while active users expand from ~4M to 15M.

Nearly all of that activity is being captured by two platforms. Kalshi and Polymarket together control about 99% of prediction market volume, effectively forming a duopoly in a fast-scaling sector.

Their strategies are diverging:

Kalshi has leveraged its Robinhood partnership to cement leadership in the U.S. retail market, focusing on accessibility, regulatory alignment, and high-frequency retail flow.

Polymarket is increasingly positioning itself as an institutional data and derivatives platform, emphasizing deeper analytics, market signaling, and sophisticated products.

Implications:

High barriers to entry for new competitors

Liquidity concentration benefits traders via tighter spreads and better pricing

Ecosystem development may split between retail-scale markets and institutional-grade prediction infrastructure

As volume accelerates, the Kalshi–Polymarket split is likely to shape how prediction markets evolve, with retail dominance on one side and institutional sophistication on the other.