Polymarket Draws Scrutiny Over Prediction-Market Manipulation Risks
Betting rapidly expanded from sports into politics, wars and news after the U.S. Supreme Court struck down the federal ban on sports betting in 2018. Americans wagered at least $160 billion on sports in 2025, while prediction markets such as Polymarket and Kalshi have turned event outcomes into financial products. The concern is that insiders may have incentives not only to predict events, but also to manipulate policy, competitions or information.
On February 28, 2026, hours before the United States bombed Iran, a Polymarket account named “Magamyman” placed unusual bets and ultimately earned $553,000. On March 10, journalist Emanuel Fabian’s reporting on a missile impact site affected $14 million in wagers, prompting bettors to pressure him to revise the story. A commentary published on March 27 renewed warnings about insider trading and regulatory gaps.
All Coverage
1 original reportsThe Backstory
The history behind this eventKalshi Launches Technology to Prevent Insider Trading in Political and Sports Markets
Kalshi is a prediction market regulated by the U.S. Commodity Futures Trading Commission, allowing users to trade on the outcomes of political and sporting events. Candidates, athletes or event personnel who wager using nonpublic information could undermine the credibility of market prices. Although the platform has long prohibited such trading, it previously relied mainly on post-trade monitoring and enforcement.
On March 23, 2026, Kalshi launched an automated pre-trade blocking tool that prevents candidates from trading in markets on their own elections. Using professional and college sports rosters, it also restricts athletes, coaches, referees and employees from trading on events involving their organizations, while adding a reporting feature. The CFTC issued market oversight guidance on March 12. Kalshi also reported two cases on February 25, including one in which a candidate wagered about $200.
Subscribe to Mark Radar Weekly
Every Friday, the week's strongest signals in your inbox. Unsubscribe anytime.
If you search news on Google, you can set Mark Radar as a preferred source—our coverage will show up more often in your results. Set as preferred source on Google →