US President Donald Trump's longtime teleprompter operator, Gabriel Perez, is under investigation by federal regulators over alleged insider trading on prediction market platform Kalshi, while the White House has placed him on unpaid leave, according to Reuters.The investigation centres on trades allegedly placed on Kalshi's "mention markets," where users bet on whether specific words or phrases will be used in public speeches. Reuters reported, citing sources familiar with the matter, that Kalshi detected the suspicious activity through its customer onboarding and market surveillance systems before referring the case to the US Commodity Futures Trading Commission (CFTC).Kalshi also froze Perez's account before profits of more than $90,000 could be withdrawn, according to Reuters. The report said Perez is cooperating with the CFTC investigation.Confirming the action taken by the White House, Press Secretary Karoline Leavitt told reporters, "The president is aware of the teleprompter operator, and the staffer is now on unpaid leave." She later added that Perez "will no longer be working at the White House."When asked whether other White House staffers had access to Kalshi or Polymarket on government devices, Leavitt said she did not know and added that, to her knowledge, no other White House or administration staffers were suspected of using privileged information to place bets.Kalshi said it had promptly alerted regulators after its internal investigation."Our surveillance team promptly flagged and referred these trades to the CFTC after an exchange investigation. We have been assisting regulators on this matter and provided evidence we collected, as we do in any referral," Robert DeNault, Kalshi's head of enforcement, told Reuters.According to Reuters, Kalshi's internal review included an interview with Perez, while market makers also reported potential irregularities in several mention-market trades through whistleblower channels.The platform's mention markets allow users to wager on whether particular words or phrases will be spoken during events such as presidential speeches, corporate earnings calls and televised broadcasts. Such contracts have drawn scrutiny from regulators over concerns they may be vulnerable to insider trading by people with advance access to prepared remarks.Kalshi announced in June that it would require employment disclosures for users trading on sensitive contracts and launch a whistleblower portal to strengthen market integrity.Prediction market platforms such as Kalshi and Polymarket have faced increasing regulatory scrutiny over concerns about market manipulation and insider trading. Earlier this year, a US Army soldier was charged over bets linked to the capture of Venezuelan President Nicolás Maduro on Polymarket, while former Congressman George Santos is also under federal investigation over alleged insider trading on Kalshi, according to Reuters.