Major League Baseball (MLB) has issued a memo prohibiting players from engaging in baseball-related event contracts on prediction market platforms, including Kalshi and Polymarket. The memo, sent from the office of commissioner Rob Manfred towards the end of the 2025 season, aims to reinforce the league’s longstanding regulations regarding betting activities.
The memo, titled “Re: Baseball Related Prediction Markets,” highlights the growing concern surrounding sports betting and its implications for the integrity of the game. It comes at a time when two pitchers from the Cleveland Guardians, Emmanuel Clase de la Cruz and Luis Leandro Ortiz Ribera, are facing serious charges linked to wire fraud and bribery for allegedly aiding in the manipulation of betting outcomes in MLB games. Prosecutors claim that the scheme involved hundreds of thousands of dollars.
According to multiple reports, the memo advises players against participating in any prediction markets or wagering on events related to baseball. Specifically, it describes these actions as violations of the league’s established betting rules. Dated August 26, 2025, the memo states, “Several companies (including Kalshi, Robinhood, and Crypto.com) are now offering what they call ‘prediction markets,’ which allow members of the public to risk money on the outcome of specific events, including baseball and other sporting events.”
The memo was disseminated to players across both major and minor league levels, with copies posted prominently near locker rooms. Despite this, news of the league’s stance on prediction markets has only gradually reached players. The document notes that the presence of baseball prediction markets had “recently come to our attention,” even though Kalshi launched its MLB markets on April 16, 2025, several months before the memo’s release.
MLB’s Cautious Approach to Prediction Markets
While MLB has embraced online sports betting in recent years, collaborating with the NBA and the PGA Tour to advocate for legalization and forming partnerships with operators like DraftKings and FanDuel, the league has maintained a cautious approach toward the emerging trend of prediction markets. Platforms such as Kalshi and Polymarket have gained traction, with the NHL already establishing agreements with both.
In contrast, the NFL has expressed apprehension about the oversight of prediction markets, suggesting that their products closely resemble traditional sports betting. NFL Commissioner Roger Goodell acknowledged this concern during a recent discussion on predictive markets, stating that the league is not prepared to enter this realm without a comprehensive regulatory framework. “For us, that’s not something we’re about to enter into,” he said. “We are going to see how things play out, both from a regulatory standpoint.”
The NBA is currently grappling with its own challenges related to sports betting, as it deals with a high-profile gambling scandal involving a current player, a coach, and a former player and coach. This incident has intensified scrutiny on how professional sports leagues manage issues surrounding betting and integrity.
As the landscape of sports betting continues to evolve, the MLB’s decision to ban players from participating in prediction markets underscores the league’s commitment to maintaining the integrity of the game. The full impact of these regulations remains to be seen, particularly as the sports betting environment becomes increasingly complex.
The MLB and the MLB Players Association (MLBPA) have been approached for further comment on this matter.
