Prediction-market companies are escalating celebrity marketing campaigns as they compete for sports-trading users and face scrutiny over whether sports-event contracts are financial products or gambling. Actress Sydney Sweeney independently contacted sports-only platform Novig while researching the sector as a potential investor, prompting the company to expand its initially modest marketing plans; she later became an equity partner, endorser and face of its campaign. Ahead of the NFL season opener, Novig released a video featuring Sweeney appearing nearly nude. The campaign followed Polymarket’s football-season commercial with LeBron James, Eli Manning, Derek Jeter, Spike Lee and Emily Ratajkowski. Kalshi and Polymarket, each valued at roughly $20 billion, have also recruited figures including Lionel Messi, Nicolás Otamendi, Rodrigo De Paul, Luka Modrić and Timothée Chalamet. The advertising push comes as prediction markets expand across the United States and confront a legal dispute over state gambling oversight. In August, the Ninth Circuit ruled Nevada could enforce its gambling laws against Kalshi’s sports-event contracts, rejecting the company’s federal-preemption argument, while differing appellate rulings could send the issue to the Supreme Court as early as next year.