George Santos is under investigation for cashing in on insider bets about himself — bad news for the credibility of prediction markets, and on-brand for a serial liar.

• Santos publicly said he'd attend the State of the Union, then secretly bet on the site Kalshi that he wouldn't show — and pocketed tens of thousands when he didn't.
• Kalshi froze his account and opened its own insider-trading probe; Santos dodged questions and even denied knowing the co-founder he claimed was his friend.
• This is the same Santos expelled from Congress over fraud, sentenced to 7 years, then freed after four months when Trump commuted his sentence.
• The case lands as Congress struggles to regulate prediction markets, which spend heavily on political campaigns.
• A US soldier was also charged in April for betting $400,000 on the capture of Venezuela's Maduro, showing the insider-info problem is spreading.

Outlook: Expect the Santos case to test whether Washington can rein in prediction markets, but real regulation looks unlikely soon.