Prediction market Kalshi said Wednesday that it had fined and suspended three political candidates for trading on their own races during primary campaigns.

“Just like in traditional financial markets, bad actors will try to cheat,” Kalshi said in a statement. “These three cases are an example of how developing proactive engineering solutions can help identify illicit trading activity.”

Kalshi described the actions taken by the politicians as “political insider trading.”

The fines ranged from $539 to more than $6,200, while the suspensions from Kalshi are set to last five years.

The candidates include Matt Klein, who is running in the Democratic primary for Minnesota’s 2nd Congressional District; Ezekiel Enriquez, who ran in the Republican primary for Texas’ 21st Congressional District; and Mark Moran, who is running in the Democratic primary for a U.S. Senate seat in Virginia.

The candidates did not immediately return requests for comment.

Enriquez finished in 11th place in the March Republican primary, when Trump-endorsed Mark Teixeira ran away with the nomination. In Virginia, Moran dropped his Democratic primary campaign against Sen. Mark Warner and is instead running as an independent.

Minnesota’s primary is not until August, when Democratic voters will pick from a number of candidates vying to succeed Rep. Angie Craig, who left her seat open to run for Senate. Klein is part of a crowded field that includes several other state legislators.

Kalshi said that “two of these cases were settlements, but one was a disciplinary action.”

The disciplinary action was taken against Moran. Kalshi said the candidate “acknowledged that these trades were improper and in violation of the Kalshi exchange rules” but “repeatedly refused to resolve this matter via settlement and stopped responding to further correspondence.” Moran’s fine was $6,229.30.

“These cases violate Kalshi’s CFTC-approved exchange rules,” Kalshi added.

The Commodity Futures Trading Commission is the federal agency that has so far taken the lead in regulating prediction markets, under the theory that event contract exchanges are much like the other commodities exchanges it regulates.

This isn’t the first time Kalshi has dealt with insider trading cases.

In February, the prediction site said it opened 200 investigations and froze a number of flagged accounts specifically over insider trading concerns. In those cases, two Kalshi users were removed from the platform.

Meanwhile, Kalshi is effectively policing itself, at least for the time being.

The financial incentive behind prediction markets has raised serious concerns about insider trading and the potential for market manipulation, particularly around elections.

U.S. laws prohibit insider trading, and the CFTC conducts platform surveillance. However, while the CFTC has asserted broad federal authority over prediction markets, several states have also brought their own civil cases against events-based exchanges, alleging that they violate state gambling statutes.