The U.S. Senate just put a hard stop on senators and their staff trading on prediction-market platforms like Polymarket and Kalshi. The rule passed unanimously by voice vote and took effect immediately on April 30. The core concern is straightforward: lawmakers and their offices may have access to sensitive information before the public. The measure was designed to stop members from making bets on upcoming events when they could be privy to information that would give them an advantage. Senator Bernie Moreno put it bluntly, saying lawmakers “have no business” engaging in that activity.
The timing stands out because prediction markets are growing quickly, not shrinking. Polymarket generated $43.36 million in protocol fees in April. So this is not a crackdown on the platforms themselves. It is a Senate ethics rule aimed at who can participate. Taken together, the vote marks one of the clearest moves yet by Congress to draw an ethics line around a fast-growing form of event-based speculation.