[Columbia University Study: Nearly 25% of Polymarket's Trading Volume May Be Wash Trading] According to a report by Coindesk, a recent study from Columbia University suggests that nearly 25% of Polymarket's trading volume may involve wash trading, where users rapidly buy and sell contracts—often trading with themselves or colluding accounts—to inflate trading activity metrics without changing their net market position. The study found that wash trading volume peaked in December 2024, accounting for nearly 60% of weekly trading volume, and persisted until October 2025. Sports and election markets were the most affected. In some weeks, over 90% of trades in these categories appeared to be wash trades. Researchers indicated that the purpose of wash trading might be to manipulate future incentive mechanisms rather than to generate profits.