Players from the NBA, NFL, and MLB call for a ban on betting ‘unders’. The unions backing professional NBA, NFL, MLB, NHL, and MLS players are calling on the Commodity Futures Trading Commission (CFTC) to ban prediction market platforms from allowing users to bet on a player's underperformance or injury, Sports Business Journal reports. In their letter, the unions cite the need for "appropriate regulations" to protect athletes and their families from "abusive and harassing behavior." The unions wrote the letter in response to the CFTC's request for comment on the regulation of prediction markets, such as those operated by Kalshi and Polymarket.