The Senate passed a resolution Thursday to ban members and staffers from trading on prediction markets.
The resolution, which changes the rules of the Senate, passed unanimously without a roll call vote. It goes into effect immediately.
“Engaging in any way in a prediction market or trying to place bets where we might have inside information deteriorates our confidence that our constituents have in us,” Sen. Bernie Moreno, R-Ohio, who introduced the resolution, said on the Senate floor.
“So it’s extremely important that the public know that from this day forward, there is no chance that any member of Congress, member of the Senate, in this case, in this resolution I’m going to propose, be involved in any prediction market whatsoever,” he said.
The resolution applies only to the Senate. Rep. Ashley Hinson, R-Iowa, said on X that she would introduce a similar resolution in the House.
“It sets a standard,” Moreno said after the resolution passed. “And I think the last thing anybody here who’s serving wants to do is be referred to Ethics for an investigation that would be the end of their political career.”
Polymarket praised the move on X. “We’re in full support of this. Our Rulebook & Terms of Service already prohibit such conduct, but codifying this into law is a step forward for the industry,” it said.
Kalshi co-founder Tarek Mansour also celebrated the resolution on X.
"Kalshi already proactively blocks members of congress and enforces against insider trading. This is a great step to increase trust in our markets by making it an industry standard," he said. "Now, let’s pass this in the House!"
The move comes amid scrutiny of apparent insider trading on the sites, including a flurry of bets made before major announcements about the Iran war. In January, a Polymarket user earned made $400,000 betting that then-Venezuelan President Nicolás Maduro would soon be out of office. A U.S. special forces soldier was charged last week with having placed that bet after he accessed classified information.
Last week, Kalshi announced that it had fined and suspended three political candidates for trading on their own races. Mark Moran, a Senate candidate in Virginia who was among those penalized, told NBC News that he placed the bet "to call attention to the fact that an entire election can be bought."
Minority Leader Chuck Schumer, D-N.Y., said Thursday on the Senate floor that the rule change was "a great thing," and urged House Speaker Mike Johnson, R-La., to follow suit.
"Speaker Johnson should immediately do the same thing in the House and prohibit House members from playing around in prediction markets, as well," Schumer said. "We must never allow Congress to turn into a casino where members representing the public can gamble on wars or economic crises or elections that would destroy the very principle of representative government."
"Just the possibility that members could have their votes influenced because of betting is a reason enough to prohibit members from meddling in the prediction markets. Of all the issues we debate in Washington, this falls clearly in the category of a no-brainer," he added.
The new restrictions are unlikely to assuage lawmakers like Sen. Chris Murphy, D-Conn., who has proposed legislation to “ban wagering on government actions, terrorism, war, assassination, and events where an individual knows or controls the outcome” completely.
“I think it’d be an endless wild goose chase to try to find everyone who might have inside information, right?" Murphy told NBC News last week. “Because staff has inside information, White House staff has more inside information, their friends then have the inside information. Their friends’ friends then have the inside information. So you can’t fix this problem by banning people from trading. You can only fix this problem by banning the markets to begin with.”
A separate Senate bill introduced last month would ban prediction markets like Kalshi and Polymarket from accepting or listing transactions related to sports events and casino-style games.
