Defining insider information on predictions

Prediction markets like Polymarket and Kalshi are booming, but they’re facing questions about users betting on information that is not publicly available, from Super Bowl performances to geopolitical crises. Advocates for the platforms say they are "truth machines" but critics say they’re a new vehicle for insider trading. WSJ’s Caitlin Ostroff explains how users are making fortunes, and why regulators are starting to take notice. Ryan Knutson hosts.

Further Listening:

- How ‘The Joker’ Rigged the Texas Lottery

- How Parlays Became the Biggest Bet in Sports

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