中期选举背书、集会、退选与辩论相关押注引发内幕交易担忧

Bets on midterm endorsements, rallies, dropouts and debates raise insider trading concerns

2026-10-09T11:00:45.461Z / https://www.cnn.com/2026/10/09/politics/midterm-election-prediction-markets

What will Vice President JD Vance say while campaigning Friday in Ohio? Will the Texas Senate candidates debate by this Thursday? And who else will get an endorsement from former President Barack Obama, who has been on endorsement spree this week?

Unlike election outcomes, all of these political questions have knowable answers. Campaign staff and speechwriters are surely in the loop. And it’s now easier than ever to cash in on insider information through the massive expansion of prediction platforms like Kalshi and Polymarket, where people can bet on real-life events.

Both companies are offering markets for every Senate, House and governor’s race this year. But they’ve also listed more than markets on midterm-related topics that are much more susceptible to insider trading because the outcomes can be known in advance.

Those super-specific midterm markets have attracted more than $20 million in trading volume, according to a new analysis from the nonpartisan Anti-Corruption Data Collective that was obtained by CNN.

These “knowable markets” include potential candidate withdrawals, major endorsements, where President Donald Trump will hold campaign events, what candidates will say at rallies and debates (known as “mention markets”), whether debates will happen, and which states will redraw their House districts.

“This is legal, and that’s part of the problem,” said Michael Hornsby, who is the co-director of the nonprofit Anti-Corruption Data Collective. “All of these things are knowable by the candidates, their campaigns, and by people close to them.”

CNN has a partnership with Kalshi and uses its data to cover major events. But CNN editorial employees aren’t permitted to use prediction platforms.

The Biden administration tried to ban markets on election outcomes, but a federal appeals court struck down the effort in October 2024. The Trump administration has embraced prediction companies and is finalizingfederal regulations that would allow election markets to keep flourishing.

With support from regulators, prediction sites now offer an average of 44 granular markets tied to each individual race, beyond simply who wins and loses, according to Hornsby’s nonpartisan group. He said companies like Kalshi and Polymarket are “creating an incentive for future public servants to trade on inside information.”

These corrupt incentives came to national attention this summer when Trump’s White House teleprompter operator was caught insider-trading on Kalshi “mention markets” for Trump speeches He settled a civil probe with federal regulators by paying a $65,000 fine

The companies say they have zero tolerance for insider trading.

So far this year, Kalshi has suspended at least six 2026 candidates for betting on their own races, in violation of platform rules. They say they’re continuously screening markets for irregular activity.

“We may see different types of insiders trying to break the rules on ‘knowable information,’ but it also may be simpler to prove insider trading in some of these cases, because the material information is narrower and easier to identify,” Kalshi’s head of enforcement, Bobby DeNault, said in a statement.

Polymarket hired a former FBI official to lead its investigations team, and regularly refers cases to the Justice Department for possible prosecution. And the company has “state-of-the-art surveillance” that includes specific measures to safeguard political markets, a spokesperson told CNN in a statement.

“Actions and decisions of political actors have incredible impacts on Americans across the country every day,” the spokesperson said. “Our markets bring transparency and information about some of the most consequential decisions being made in the country – information that should not be contained to lobbyists, donors and political insiders.”

The Anti-Corruption Data Collective report flagged possible suspicious activity in a Kalshi market about whether Graham Platner would drop out of the Maine Senate race, which is one of the “knowable markets” more prone to insider trading.

Platner won the Democratic nomination in June. Just a few weeks later, an ex-girlfriend publicly accused him of rape, which he denied. His support within the party collapsed and within days, he withdrew from the race.

Researchers from the watchdog group found dozens of potentially correlated trades on Kalshi, on longshot bets predicting Platner’s withdrawal, placed one night before, and immediately before, the rape accusation became public.

These patterns don’t prove insider trading, however, and the trades could be unrelated.

But it’s easy to imagine who might learn about the rape claims before the story came out: campaign staffers, donors, opposition researchers from both parties, other reporters, family and friends of the ex-girlfriend, and others.

“It started to get out that a really bad story was coming, at least one week beforehand,” a Democratic operative told CNN. “It could have been someone going off a rumor. It became a really poorly kept secret in Maine and DC.”

In a call with reporters on Tuesday, Kalshi’s top lobbyist, John Bivona, said the company screens its customers and prevents them from participating in markets where they could influence the outcome. This applies to candidates, campaign staffers, party officials, vendors, pollsters, and election workers.

Bivona said Kalshi follows “a stricter standard than federal insider trading law” and “scans every trade for suspicious timing and coordinated activity.”

Federal law makes it a crime to trade on non-public information when there is a duty of confidentiality – like trade secrets or government intelligence. Insider trading charges can be also brought against people who trade based on a tip from someone who was obligated to keep the information secret.