The connection between professional sports and betting is becoming more complicated thanks to predictive markets. On one side, five major US leagues, including the NBA, have joined their players’ unions to protect athletes and their families from betting-related harassment. At the same time, NBA stars LeBron James and Giannis Antetokounmpo have entered the growing business.
LeBron has partnered with Polymarket, while Giannis has made a separate deal with Kalshi. These two developments are not directly linked. No one has accused LeBron or Giannis of doing anything wrong. Still, they show how sports and betting-related businesses are becoming more closely connected.
On September 15, the five major US sports leagues- the NFL, NBA, MLB, NHL, and MLS and their players’ unions sent a joint letter to gaming regulators in 35 states and Washington, D.C., as per the X post by ESPN senior NFL Insider Adam Schefter.
The X update covered how they asked regulators to take stronger action against people who threaten or harass athletes, coaches, officials, team staff, and their families because of sports bets.
The leagues said losing a bet should never give anyone the right to personally target an athlete. They want regulators to give a mandatory lifetime betting ban to anyone who is found to have seriously threatened or harassed sports personnel.
They also want sportsbooks and states to improve how they share information. If one state bans a bettor for threatening an athlete, the leagues want that ban to apply in other states too.
Meanwhile, LeBron and Giannis are entering prediction markets
At the same time, two of the NBA’s biggest stars have taken different steps into the prediction-market business.
As per the report by Mike Wilson of the NYTimes, Giannis Antetokounmpo became a shareholder in Kalshi in February 2026. This made him the first NBA player to directly invest in the company. Kalshi will also work with him on marketing and live events.
However, Giannis cannot trade on markets linked to the NBA. Kalshi does not allow insider trading or market manipulation. The same NYTimes report also says the NBA’s collective bargaining agreement allows players to promote and hold small stakes in sports betting companies under certain conditions.
The move still faced criticism online. Some people questioned whether an active NBA player should have a financial connection with a prediction-market platform.
Then came LeBron James, who has announced an exclusive partnership with Polymarket, according to Dave Grendzynski’s report on Action Network. He became the first NBA player to sign an individual deal with the prediction-market platform. The partnership will initially focus on football.
Polymarket has also grown its presence in sports. It recently became the official prediction market of the ATP.
Prediction markets are not the same as traditional sportsbooks. However, they still let people take positions on future events and results. This links athletes and these companies to a sensitive issue.
There is nothing wrong with athletes working with prediction-market companies if they follow league rules and the law. But professional sports must also avoid even the appearance of a conflict of interest.
This becomes more important when leagues are asking regulators to protect athletes from the negative side of sports betting.
The main point is not whether LeBron or Giannis are responsible for betting-related harassment. They are not. The bigger story is that sports are becoming more connected to the prediction-market business, while leagues are also trying to create stricter rules to protect athletes.
For fans, this creates a difficult balance. Betting and prediction markets can give fans another way to engage with sports. But protecting the athletes and other people who make sports possible must always come first.