Prediction markets spend massive on movie star campaigns at the same time as Sydney Sweeney and LeBron James adverts stir backlash

The advertisement came a day after Polymarket enlisted basketball star LeBron James for a star-packed football-season commercial featuring other prominent athletes, including Eli Manning and Derek Jeter, along with entertainment figures such as filmmaker Spike Lee and model Emily Ratajkowski.

“Selling gambling by selling sex. Society is crumbling before our eyes,” one user wrote of Novig’s promotion.

“Damn, I can’t believe LeBron is a sellout now,” another user wrote in response to Polymarket’s ad.

LeBron’s Polymarket deal knocks him out of GOAT contention. The title stays with Michael Jordan, a man untainted by the allure of sports gambling.

— Joe Wrote (@joewrote) September 9, 2026

The celebrity advertising push comes as prediction markets expand rapidly across the United States, despite a contentious legal and regulatory fight. The platforms let users buy and sell contracts on outcomes ranging from sports and politics to pop culture, often with just a few clicks. Their rapid growth has intensified scrutiny over whether sports-related contracts should be treated as federally regulated financial products or gambling under state law.

To sustain that momentum, prediction market companies are pouring money into high-profile marketing campaigns. Kalshi and Polymarket—two of the sector’s largest players, each valued at roughly $20 billion—have spent heavily to recruit celebrities to promote their platforms. Because sports-related contracts account for a large share of activity on their platforms, the companies have timed major campaigns around the start of major sports seasons. 

In the lead-up to the World Cup, soccer’s biggest international tournament, Kalshi ran ads featuring Argentina captain Lionel Messi alongside teammates Nicolás Otamendi and Rodrigo De Paul as part of a commercial partnership with the country’s national football federation. The platform also featured Luka Modrić, captain of Croatia’s national team, in a separate campaign.

Before that, Kalshi also enlisted Oscar-nominated actor Timothée Chalamet for a series of ads set in mundane places, including a dentist’s office and a music store.

The marketing push comes as prediction markets confront mounting uncertainty over their legal future. In August, the Ninth Circuit ruled that Nevada could enforce its gambling laws against Kalshi’s sports-event contracts, rejecting the company’s argument that federal commodities law preempted state oversight. 

With appellate courts now divided, the dispute over who gets to regulate the fast-growing industry could reach the Supreme Court as early as next year.