Approximately $200 million in trades on Polymarket in the first half of the year were flagged as potential insider trading
According to Bloomberg, as prediction markets like Polymarket and Kalshi expand, the issue of betting using non-public information or informational advantages is receiving more scrutiny. Bloomberg Businessweek analyzed approximately 34,000 potential insider trading cases flagged by Polysights between August 2025 and June 2026; these related trades exhibited characteristics such as newly created accounts, low probability entries, large bets, or high trading concentration, but it cannot be determined that traders violated rules based on this.Data shows that from January 1 to June 30 of this year, the amount of suspicious trades flagged on Polymarket was approximately $200 million, with geopolitical and war-related markets driving a significant increase in abnormal trading volume. The profits from potential insider trading are highly concentrated, with the top 1% of accounts in profit wallets earning more than half of the gains, and 57% of related wallets created less than 24 hours before the trades. Some traders are reducing the likelihood of being discovered by using multiple associated wallets and splitting orders. For example, 38 associated addresses placed bets in 90 geopolitical markets related to Iran and Venezuela, achieving a win rate of 98%, with total profits of $1.6 million, and withdrew funds using the same Coinbase deposit address.Polymarket stated that it will monitor insider trading and other illegal activities, and has so far referred nearly 100 wallets to law enforcement agencies. Kalshi has also strengthened identity and employment information checks, and restricted participation in related markets by political candidates, athletes, and others who may influence outcomes.