Atlanta Braves outfielder Ronald Acuña Jr. has entered into a partnership with Kalshi, becoming the first active Major League Baseball player reported to endorse a prediction market platform.
A Kalshi advertisement featuring Acuña aired during the Braves’ National League Division Series game against the Los Angeles Dodgers on 7 October.
The player endorsement extends Kalshi’s baseball marketing beyond its August agreements with five MLB clubs: the Braves, Boston Red Sox, Los Angeles Dodgers, San Diego Padres and San Francisco Giants. These team arrangements cover advertising and fan promotions; the Acuña partnership adds an individual athlete to the company’s campaigns.
The deal also draws attention to integrity rules. MLB and its players’ association warned players in 2025 against trading baseball event contracts.
Kalshi’s published rules for a contract involving Acuña’s game statistics likewise prohibit current league players, coaches and staff from trading it.
The deal comes after MLB named rival platform Polymarket its official prediction market exchange in March and signed an information-sharing agreement with the Commodity Futures Trading Commission.
The league said it would also seek integrity arrangements with other exchanges offering baseball contracts, while restricting markets involving potentially manipulable events such as individual pitches.
Kalshi operates under federal derivatives oversight, but whether sports event contracts are also subject to state gambling rules remains contested in litigation.
Acuña’s endorsement arrives as prediction market companies expand their sports marketing amid that unresolved dispute.
A Kalshi contract involving Acuña’s game statistics also bars players’ immediate family and household members from trading it
