Massachusetts sues Kalshi over alleged illegal sports wagering
12 September 2025 | By Pat Evans
Summary
The Massachusetts Attorney General, Andrea Campbell, has sued Kalshi in Suffolk County Superior Court, alleging the prediction-market operator is functioning as an illegal sports betting platform.
The complaint claims Kalshi accepted more than $1 billion in sports wagers in the first half of 2025 without appropriate licensing and that over 75% of the platform’s volume is on sports markets. The suit argues Kalshi creates “a digital gambling experience”, uses behavioural design mechanics from gambling psychology, and recently added a parlay product while marketing itself as sports betting.
The action adds to mounting regulatory pressure: several states issued cease-and-desist letters this spring, and Kalshi is already litigating with regulators and facing separate suits from tribes and state authorities. The case sits alongside wider debate over prediction markets and the Commodity Futures Trading Commission’s approach to oversight.
Key Points
- Massachusetts AG Andrea Campbell filed suit alleging Kalshi operates illegal sports wagering and seeks a court block.
- The complaint says Kalshi took over $1bn in sports wagers in H1 2025, with more than 75% of volume on sports markets.
- The suit accuses Kalshi of mirroring a digital gambling experience and using behavioural design techniques.
- Kalshi has faced cease-and-desist letters from multiple states and legal challenges from regulators and tribal groups.
- Kalshi has countered with lawsuits in several states and won some preliminary injunctions while appeals and other cases continue.
Context and relevance
This case is a high-profile test of how prediction markets that trade on sports events will be treated by state regulators and courts. With major volumes reportedly tied to sports and the company advertising sports-style products, regulators argue Kalshi is functionally indistinguishable from conventional sportsbooks.
The outcome could affect a range of players: prediction-market operators, licensed sportsbook firms exploring event markets, state gaming regulators concerned about licencing and consumer protection, and tribal gaming interests asserting statutory rights. It also sits against a backdrop of federal debate over the CFTC’s role and the adequacy of oversight for these markets.
Why should I read this?
Short version — this could change the rules of the game. If you follow sports betting, prediction markets or regulatory risk, this is worth five minutes of your time. The suit targets big volumes, questions how these products are designed and marketed, and could force big shifts in where and how event contracts are offered. Basically: it matters for licences, compliance and who wins or loses access to these markets.
