Kalshi CEO Tarek Mansour does not view Polymarket as his main competitor, according to comments reported by Front Office Sports. Instead, he identified derivatives giant CME Group, brokerage Robinhood, and sportsbook operators as the rivals he watches most closely. Speaking at Kalshi's headquarters in New York City, Mansour told FOS that "when I think about competition, I don't think about Polymarket, honestly, as much as some of the others." He emphasized that Kalshi maintains a 'whole suite of competitors' and is "very customer obsessed and competitor aware." This perspective recasts the competitive landscape beyond the traditional two-horse race between Kalshi and Polymarket that has dominated industry discussions.
Kalshi dominates the regulated US prediction market with approximately 91% market share, as reported by Bank of America analysts, with Polymarket in second place and Underdog third. However, raw volume data shows a closer competition, with Kalshi trading about $9.8 billion over the past 30 days against Polymarket's $9.9 billion, according to DeFi Rate. Despite this, Kalshi maintains its leadership position by holding roughly $1 billion of the $1.6 billion in industry open interest and listing about 97% of all active markets. Mansour noted that "it's not that clear who's second" in the competitive landscape, highlighting the expanding field of rivals.
The competitive field has broadened significantly with CME Group launching FanDuel Predicts with the sportsbook in December, trading event contracts on sports outcomes and economic data. Robinhood built its prediction markets hub on Kalshi's own exchange in 2025 before routing some World Cup and baseball contracts to Rothera, its venue with Susquehanna. Additionally, DraftKings, Novig, and Coinbase have also moved into prediction markets, making second place increasingly difficult to determine. Polymarket continues to rely on its offshore platform for heavy offshore trading volume from US users using VPNs.
Recent regulatory concerns have emerged around Polymarket's operations, with two indictments involving trades made on Polymarket's international platform. In April, a U.S. soldier was indicted by the Department of Justice for allegedly using inside information to make more than $400,000 betting on when the U.S. military would capture Venezuelan President Nicolás Maduro. Last month, a Google software engineer was indicted for allegedly using confidential internal information to make more than $1.2 million on Polymarket betting on markets related to who the most-searched person of 2025 would be. Both incidents involved trades made on Polymarket's international platform, which is only available to U.S. users who use a VPN. Mansour expressed hope that Polymarket would "come under the regulated umbrella" to address these concerns.
For now, Kalshi controls the compliant US market while Polymarket and the expanding field chase its lead. The 2026 World Cup lifted both platforms, with a single World Cup winner market drawing tens of millions in daily bets. The industry has seen rapid growth in the last year, with Mansour noting that increased competition is good for the market because "it grows the market and grows the pie." However, the CFTC proposed a 267-page rule on June 10 that would permit most sports contracts while barring in-game props, officiating bets, and pre-collegiate sports, with a 45-day comment window. The regulatory framework could significantly impact the competitive landscape as it would restrict bets that most regulated platforms in the U.S. don't currently offer.
