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John Oliver examines prediction markets on Last Week Tonight

tvApr 20, 202629621

On Last Week Tonight Season 13 Episode 8, aired April 19, 2026, John Oliver examined prediction market platforms Polymarket and Kalshi and detailed insider-trading risks. Oliver highlighted investor ties to those platforms that include Donald Trump Jr. He showed that Polymarket lists contracts on U.S. elections and other political outcomes where traders with nonpublic information could profit. Oliver urged regulators and exchanges to strengthen oversight to prevent market manipulation and insider trading.

Key Highlights

John Oliver named Polymarket and Kalshi and warned of insider-trading risks.
Oliver highlighted investor ties that include Donald Trump Jr.
He warned that private information can let traders profit before public announcements.
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