A recent scandal involving a Green Beret arrested for betting on a classified U.S. raid may be more than an isolated incident, as a new study suggests that informed traders like him play a significant role in shaping prediction market prices. The study, conducted by researchers from London Business School and Yale, analyzed over 1.72 million accounts and $13.76 billion in trading volume on Polymarket, revealing that just 3% of traders are responsible for most price discovery. These traders consistently demonstrate an ability to predict outcomes and move prices in the right direction, while the remaining 97% tend to lose money.
The researchers used a unique approach to distinguish between skill and luck, re-running each trader's bets 10,000 times with the direction of the bet reversed. The results showed that among the biggest winners, only 12% consistently outperformed the benchmark, while many apparent winners were found to be simply lucky.
The study's findings have significant implications for our understanding of prediction markets, suggesting that it is the informed minority, rather than the crowd, that drives market accuracy. The activity of skilled traders improves market accuracy, particularly in the final stages before an event's resolution, and they are often the first to react to new information.
However, the study also raises concerns about the potential for insider trading, highlighting the need for prediction markets to ensure that trading on non-public information is strictly prohibited.