Polymarket Captures 44% of Kalshi's Football Trading Volume in Rapid Growth

Polymarket has made impressive strides in the US sports prediction market, capturing approximately 43.8% of Kalshi's football trading volume shortly after launching its US operations in late 2025. This rapid growth is particularly notable given that Kalshi had a substantial head start in the market.

In a recent 30-day period, the combined sports trading volume across Polymarket and Kalshi reached around $9.33 billion, with Kalshi accounting for about $6.03 billion and Polymarket handling roughly $3.30 billion. However, the dynamics of football trading reveal a more complex picture. During the first week of the 2026 NFL season, Kalshi processed over $983 million in NFL contracts, while Polymarket reported around $27.6 million for the same timeframe.

How Kalshi Built Its Lead

Kalshi entered the sports event contracts space in early 2025, quickly establishing itself as the go-to platform for regulated prediction market activities in the US. It introduced combo products that allowed traders to bundle multiple outcomes and integrated more effectively with traditional financial systems. Kalshi achieved a record single-day volume of $2.29 billion in early September 2026, primarily driven by sports markets.

Polymarket's Strategy

Polymarket's international platform, built on cryptocurrency infrastructure, has been a significant liquidity venue before entering the US market. The launch of its US arm in late 2025 allowed it to leverage the momentum gained from international trading. The 2026 World Cup served as a catalyst for Polymarket, generating billions in trading activity and helping to establish a user base that continued into the NFL and college football seasons.

Recent Volume Surge

In the week of September 7-13, 2026, Polymarket experienced a staggering 4,399% increase in NFL contract trading on its Global platform, reaching $27.62 million. The US arm saw a 1,760% week-over-week gain, totaling $23.20 million. Overall, Polymarket's sports trading volume surged by approximately 104.7%, reaching around $499 million in a single week.

Challenges Ahead

Despite Polymarket's rapid growth, it faces challenges, including temporary outages during peak trading periods that could hinder its competitive edge. As the combined weekly volume of $14.1 billion demonstrates, the liquidity of prediction markets is becoming increasingly significant, but Kalshi's established regulatory relationships and infrastructure present ongoing challenges for Polymarket's expansion.