A shadow fell over Major League Baseball in late 2025, triggered by a stark warning issued directly to players. A memo, originating from Commissioner Rob Manfred’s office and co-signed by the players union, explicitly forbade participation in prediction markets like Kalshi and Polymarket – platforms where individuals wager on the outcome of specific events, including baseball games.
The directive wasn’t issued in a vacuum. It arrived amidst a burgeoning scandal involving two Cleveland Guardians pitchers, Emmanuel Clase and Luis Leandro Ortiz Ribera, facing serious federal charges. Prosecutors allege a conspiracy to manipulate pitch outcomes for illicit financial gain, a scheme reportedly involving hundreds of thousands of dollars.
The memo detailed the league’s concerns, outlining how these “prediction markets” allowed the public to gamble on baseball events. Screenshots from Kalshi, dating back to May, were included as evidence of the platforms’ existence and functionality. The league’s stance was clear: any involvement in these markets constituted a violation of existing betting rules.
Despite the memo’s circulation in August – distributed to players at both major and minor league levels, even posted in locker room areas – awareness of the league’s position spread slowly. The timing also raised eyebrows, as Kalshi had launched its MLB markets over four months prior to the memo’s release.
This move represents a significant shift in MLB’s approach to the evolving landscape of sports gambling. While actively embracing traditional online sports betting, partnering with giants like DraftKings and FanDuel, the league had remained largely silent on the rise of prediction markets.
Other leagues are grappling with similar concerns. The NHL has cautiously entered agreements with Kalshi and Polymarket, while the NFL has expressed reservations about inadequate oversight, stating these markets “mimic sports betting.” The NBA, currently navigating its own high-profile gambling scandal, faces increased scrutiny over its handling of these issues.
The NFL’s stance, articulated by Commissioner Roger Goodell in December, mirrors the growing apprehension. Goodell stated the league would remain on the sidelines until a robust regulatory framework is established and the risks to the integrity of the sport are fully understood. He emphasized the ongoing legal challenges surrounding these platforms.
The MLB’s memo and the unfolding legal case signal a turning point. The league is drawing a firm line, attempting to safeguard the game’s integrity in the face of increasingly sophisticated and potentially destabilizing betting practices. The future of prediction markets in professional sports hangs in the balance.
