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

A recent scandal involving a Green Beret accused of 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 the small group of informed traders who actually influence prices on platforms like Polymarket, while the majority of participants incur losses. 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 between 2023 and 2025. The findings indicate that a mere 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, using the same markets, moments, and dollar amounts but with the direction determined by a coin flip. The results showed that only 12% of the biggest winners by raw profit consistently outperformed the benchmark, while many apparent winners did not sustain their performance over time. The study also found that the activity of skilled traders improves market accuracy, particularly in the final stages before resolution, and that they are the first to react to new information. However, this raises concerns when the information is not public or is not supposed to be. The researchers cite the example of the US removal of Nicolás Maduro from power in Venezuela, where three newly created Polymarket accounts placed unusually large bets on the contract before the operation, collectively making over $630,000. While there is no evidence of wrongdoing, the incident highlights the risk of insider trades, which can move prices aggressively but are rare and concentrated in a handful of events. 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 informed traders who drive price discovery.