A coalition of the largest US professional sports player unions has asked the Commodity Futures Trading Commission (CFTC) to prohibit several categories of sports event contracts at platforms like Kalshi and Polymarket, putting the unions in direct opposition to the leagues that have signed commercial deals with the same platforms.
Key Takeaways:
- Player unions for the NFL, MLB, NBA, NHL, and MLS jointly asked the CFTC to ban “negative outcome” and “mention” event contracts.
- The NHL has data partnerships with both Polymarket and Kalshi, and Polymarket is MLB’s exclusive prediction-market partner.
- The CFTC received over 1,500 public comments before its rulemaking input window closed on April 30.
Player Associations Across Five Major US Sports Leagues File Joint Comment
The joint comment, filed on April 30 (the final day of the window) by player associations representing the NFL, MLB, NBA, NHL, and MLS through the lobbying firm Elevate Government Affairs, urged the CFTC to ban contracts based on a “negative” outcome that can be manipulated by a single individual, including bets on whether an athlete is injured or penalized. The unions also asked for a ban on “mention contracts” tied to whether specific words like “concussion” are spoken during live broadcasts, calling them “just another way of betting on a negative outcome.”
The unions argued that prop bets on individual athlete performance expose players and their families to harassment from disgruntled bettors, citing a New York Times survey published in The Athletic from November 2025, which reported that 78% of professional baseball players said legalized sports betting had changed how fans treat them. “Individuals targeting our members do not distinguish between state-regulated wagers and contracts offered on prediction markets,” the unions wrote. “From their point of view, a bet is a bet regardless of where it is placed.” The Athletic piece also includes somber testimonies from players of the NHL, the NFL, and the NBA, though it is worth noting that it does not in any way mention prediction markets across the piece.
The NHL last year became the first US pro league to enter the prediction-market space, signing multi-year data partnerships with both Polymarket and Kalshi. MLB has Polymarket as its exclusive prediction-market partner under a multi-year agreement and has signed a memorandum of understanding with the CFTC on>also filed comments asking the agency to monitor susceptible markets. Spillane’s NBA letter further called for raising the minimum trading age to 21, in line with the legal sports betting age in most US states.
The CFTC closed its 45-day rulemaking input window on April 30 with over 1,500 public comments received. Chair Michael Selig defended the agency’s posture in response to a Wall Street Journal editorial in a letter to the editor published May 1, writing that the CFTC holds “exclusive authority over prediction markets” under the Commodity Exchange Act and warning that restrictive rulemaking would push activity offshore.
Selig has repeatedly framed exchanges as self-regulatory organizations responsible for policing their own markets, at the time when Toronto Raptors forward Jontay Porter was banned for life in April 2024 for sharing confidential information with bettors who had wagered he would underperform statistical “under” lines. Former Miami Heat guard Terry Rozier was arrested in October 2025 as part of a federal investigation into prop-bet manipulation, with prosecutors expected to file additional charges by mid-May.
