New Study Reveals Only a Small Group of Informed Traders Drive Prediction Market Accuracy

A recent scandal involving a Green Beret arrested for betting on a classified US raid may be more than an isolated incident, according to a new study. The research suggests that this individual may be an extreme example of a small group of informed traders who actually influence prices on platforms like Polymarket, while the majority of participants lose money. The study, conducted by researchers from London Business School and Yale, analyzed 1.72 million accounts and $13.76 billion in trading volume on Polymarket from 2023 to 2025. The findings indicate that just 3% of traders are responsible for most price discovery, consistently predicting outcomes and moving prices in the right direction. In contrast, the remaining 97% of traders provide liquidity and generate volume but tend to be on the losing side of trades against the informed minority. To distinguish between skill and luck, the researchers simulated each trader's bets 10,000 times, keeping everything the same except the direction. The results showed that among the biggest winners by raw profit, only 12% consistently outperformed the benchmark, and many apparent winners did not sustain their performance over time. The study also found that when skilled traders account for a larger share of trading, prices move closer to the correct outcome, especially in the final stretch before resolution. However, the same edge that makes skilled traders valuable to price discovery raises concerns when that information is not public or is not supposed to be. The researchers cited a concrete example of this risk, involving three newly created Polymarket accounts that placed unusually large bets on a contract related to the US removal of Nicolás Maduro from power in Venezuela. The accounts collectively made over $630,000, but there is no evidence of any wrongdoing. The study's findings challenge the idea that prediction markets work due to the collective knowledge of their participants, instead suggesting that they work because of the presence of informed traders.