A study from Stanford and Singapore Management University reveals that Polymarket's five-minute Bitcoin prediction markets are vulnerable to price manipulation. The research shows sophisticated traders can influence Bitcoin's spot price just before contract settlement, profiting at the expense of ordinary users.
Analysis of trading activity after Polymarket launched these contracts in July 2024 found sharp price movements followed by rapid reversals, consistent with manipulation. The study estimates this transferred about $1.28 million from retail traders to manipulators. Extending contract durations to 15 minutes largely eliminated the effect.
The findings carry implications as prediction markets expand. Platforms like Kalshi and Polymarket posted record volumes in June, fueled by the 2026 FIFA World Cup. This growth is occurring alongside legal battles over whether the CFTC or states have primary regulatory authority.