Baltimore Sues Kalshi, Polymarket — And Drags Coinbase, Robinhood Into It Too

The list of defendants in this lawsuit is long — surprisingly so. The plaintiffs are Baltimore Mayor Brandon Scott and the Baltimore City Council, and the defendants include not just the two most prominent prediction markets, Kalshi and Polymarket, but also the far more familiar trading apps Coinbase, Robinhood, and Webull.

The case centers on "illegal sports betting." The city isn't just taking issue with Kalshi and Polymarket, the two platforms that offer contracts on game outcomes — it's also treating the channels that let everyday users place orders on those contracts as part of the same chain of allegations. In other words, this isn't a suit against a single product, but against an entire "market-making plus distribution" setup.

For Kalshi and Polymarket, contracts on sporting event outcomes have long occupied a gray zone between betting and financial derivatives, with state regulators taking inconsistent stances. What stands out about Baltimore's approach is that it extends the battle line beyond the platforms themselves to the downstream channels that let retail users access these contracts — meaning this dispute is no longer just a problem for Kalshi and Polymarket alone.

For now, public information is limited to the filing details disclosed by The Block; the timing of the lawsuit, the court handling the case, and the specifics of the damages sought have not yet been made public.