On July 21, according to Bloomberg, as prediction markets like Polymarket and Kalshi expand, the issue of using non-public information or informational advantages to place bets is facing increased scrutiny. Bloomberg Businessweek analyzed approximately 34,000 potential insider trading cases flagged by Polysights between August 2025 and June 2026. These trades are characterized by newly created accounts, low-probability entries, large bets, or high trade concentration, but this alone does not confirm that traders violated rules. Data shows that from January 1 to June 30 this year, the amount of suspicious transactions flagged on Polymarket was approximately $200 million, with geopolitical and war-related markets driving a significant increase in abnormal trading volume. Profits from potential insider trading are highly concentrated, with the top 1% of profitable wallets capturing more than half of the gains. 57% of the related wallets were created less than 24 hours before trading. Some traders are reducing the likelihood of detection by using multiple linked wallets and splitting orders. For example, 38 linked addresses placed bets in 90 geopolitical markets related to Iran and Venezuela, achieving a win rate of 98% and total profits of $1.6 million. They withdrew funds through the same Coinbase deposit address. Polymarket stated that it monitors insider trading and other illegal activities and has so far handed over nearly 100 wallets to law enforcement agencies. Kalshi has also strengthened identity and employment information reviews and restricted political candidates, athletes, and other individuals who could influence outcomes from participating in related markets.