Report: Polymarket may have a wider insider trading problem, with a few wallets reaping the majority of profits.

A new report from the non-profit research firm Anti-Corruption Data Collective (ACDC) suggests that the prediction market platform Polymarket may be involved in a wider range of insider trading issues than the previous "Green Berets betting on the Venezuelan attack." The study analyzed 435,000 markets settled between January 2021 and mid-March 2026, totaling $54.4 billion in trading volume. It found an unusually high success rate for low-probability bets in government decision-making markets related to military and defense. Data shows that the average success rate of such "niche bets" in political markets is approximately 14%, while some cases in military-related contracts have success rates exceeding 50%. The research argues that these markets are difficult to predict using only publicly available information and are more susceptible to information asymmetry, including insider trading or expert information advantages. The report also points out that Polymarket's profits are highly concentrated. Research from London Business School and Yale University shows that approximately 3% of traders contribute the majority of price discovery on the platform; blockchain analytics firm Solidus Labs found that less than 1% of wallets capture about half of the profits. Taking the June 2025 US airstrikes against Iran as an example, hours before the attack, 19 low-probability bets totaling $164,000 were concentrated on the "YES" contract that ultimately paid out. Eight wallets collectively profited approximately $1.8 million, with a single wallet profiting nearly $500,000. Although the Pentagon deliberately concealed its operations using decoy bombers and long-range stealth aircraft, a few traders still accurately predicted the outcome. The ACDC recommends that Polymarket strengthen identity verification, implement conditional payouts for suspicious bets, limit markets where a few people determine the outcome, and reduce overly granular contract designs. The report further calls for a broader discussion on whether the public should bet on such events. (CoinDesk)