As Patrick Mahomes prepared for his 2026-2027 NFL regular-season debut, U.S. prediction markets reached a historic milestone during the opening week. Kalshi and Polymarket together exceeded $1 billion in NFL trading activity within the first six days of Week 1, marking a significant achievement in the industry. Specifically, Kalshi recorded an impressive NFL volume of $983.4 million, as reported by DeFi Rate, leading the market by a considerable margin. The Kansas City Chiefs, led by Mahomes, delivered an overwhelming 31-10 victory against the Denver Broncos on Monday Night Football, culminating in the most significant week ever for prediction markets.
Prior to the highly anticipated matchup in Kansas City, it became evident that the industry was on track to surpass previous weekly activity records. The AFC West clash only enhanced the impressive totals. Overall, trading volume for the week reached a record $15.9 billion, a 16% increase compared to the previous week, according to data from Bank of America.
Kalshi and Polymarket emerged as the dominant players in the prediction market sphere through Week 1. While Kalshi's market share slipped to 82% for the week ending September 13, down from 86% the week before, the newcomer still maintained a substantial lead over Polymarket, which was its nearest competitor. Polymarket stood out with 762,000 app downloads, surpassing Kalshi as well as DraftKings and FanDuel in that department. This influx represented a staggering 13,509% weekly growth, accounting for 25% of total category downloads, according to a statement from Polymarket.
Across the prediction market landscape, operators registered impressive gains in comparison to Labor Day weekend, which was dominated by college football but lacked any NFL contests. DraftKings and Underdog experienced remarkable growth, with weekly increases of 125% and 119%, respectively. Other operators, including Polymarket, Crypto.com, and Novig, recorded gains of at least 30%, leading with a 46% weekly increase from Polymarket.
An intriguing insight emerged regarding activity on Sundays at Kalshi, which only exceeded previous daily activity by $34 million, according to Bank of America data. Typically, NFL Sundays witness much higher volume than College Football Saturdays due to the strong demand for NFL offerings. BofA analyst Shaun Kelley suggested that Kalshi might be leaning too heavily on college sports for its volume. He also pointed out that enhancements at Robinhood could contribute to Kalshi’s decline. Robinhood recently acquired a minority stake in Crypto.com and established a deal to route NFL contracts to OG.com, its regulated prediction market platform.
Crypto.com saw a 40% weekly increase, indicating the potential impact of its partnership with Robinhood on Kalshi's downturn.
Throughout the week, beyond just football, Crypto.com reported a trading volume of $350 million; its figures showed a growth of 41%. While Kalshi and Polymarket amassed over $15 billion in weekly trading volume, four other operators achieved at least $300 million in activity. Notably, Novig, buoyed by a popular advertisement featuring Sydney Sweeney, increased its volume by nearly 34%.
Looking ahead, the prediction markets are poised for a boost as several prominent teams will headline primetime events in Week 2. The Buffalo Bills will make their regular-season debut at Highmark Stadium against the Detroit Lions on Thursday, generating excitement among the "Bills Mafia" for their new $2.2 billion stadium. New York ranks among the largest sports betting markets in the nation, potentially enhancing weekly totals on prediction markets. The week will conclude with a Monday Night Football clash between the New York Giants and the Los Angeles Rams, a team widely considered a Super Bowl favorite, with Kalshi indicating a 75% probability of the Rams defeating the Giants as of Wednesday afternoon.
"It’s going to be a great test for our team," stated Giants quarterback Jaxson Dart on Wednesday.
