Polymarket's transactions of about $200 million were marked as potential insider transactions in the first half of the year

On 21 July, according to Bloomberg, the use of non-public information or the advantage of information to bets is being further examined as the forecast markets of Polymarket and Kalshi expand. The Bloomberg Business Weekly analysed some 34,000 potential insider transactions marked by Polysights between August 2025 and June 2026; the transactions involved had the characteristics of a new account, low-probability entry, high-value bets or a high concentration of transactions, but it was not possible to determine that the dealer had violated the rules. Data show that between 1 January and 30 June of this year, the amount of suspicious transactions marked on Polymark was approximately $200 million, of which geopolitical and war-related markets contributed to a significant increase in unusual transactions. Potential insider transactions are highly profitable, with the top 1 per cent of the profit wallets receiving more than half of the proceeds and 57 per cent of the related wallets being created less than 24 hours before the transaction. Some traders are reducing the likelihood of detection through multiple related wallets and split orders. For example, 38 related addresses were betted in 90 geopolitical markets related to Iran and Venezuela, with a 98 per cent winner and a combined profit of $1.6 million, and were drawn from the same Coinbase filling address. Polymarket indicated that it would monitor insider trading and other illegal activities and had so far handed over nearly 100 wallets to law enforcement agencies. Kalshi has also strengthened the review of identity and employment information and restricted the participation of political candidates, athletes and others, who may influence the outcome, in relevant markets。