A Stanford study finds traders manipulated Polymarket's five-minute Bitcoin bets, extracting $8.2 million from retail users who bore 93% of losses. By placing large orders on Binance just before settlement, 821 traders could nudge the reference price to win their wagers. The study notes the manipulation is absent in 15-minute contracts, suggesting longer settlement windows as a solution for prediction markets.
Five-minute Bitcoin contract design
- ▪The five-minute contracts settle against a Chainlink oracle that averages Bitcoin's spot price across major exchanges
- ▪On February 12, 2026, Polymarket launched a five-minute binary contract where traders bet if Bitcoin's price would be higher or lower at the end of the window
Settlement manipulation mechanics
- ▪The study's authors are David Dai and Ruizhe Jia of Stanford University and Shihao Yu of Singapore Management University
- ▪Binance's price is a close proxy for the oracle, finishing on the same side of the strike price 85% of the time
- ▪The study found traders could manipulate outcomes by placing large orders on the Binance exchange in the final seconds before settlement to move the reference price
Binance order flow evidence
- ▪The price movements typically reverted within ten seconds after settlement, a sign of manipulation rather than trading on new information
- ▪After the contract's launch, net order flow on Binance jumped about 50% in the final ten seconds before settlement
Manipulator wallet profits
- ▪Researchers identified 821 wallets, or about 1 in 300 traders, that profited from the manipulation pattern
- ▪These manipulating traders extracted $8.2 million from the pushed cycles while breaking even in non-pushed cycles
Retail trader losses
- ▪The study described the contract as a "machine for wealth transfer" from retail bettors to a small group of manipulators
- ▪Retail traders sustained 93% of the losses in the manipulated betting cycles
Fifteen-minute contract comparison
- ▪The manipulation pattern was significantly reduced or absent in Polymarket's longer, 15-minute contracts
- ▪A Polymarket spokesperson stated the platform is considering changing settlement methods to use prices over a longer period
- ▪The study's findings could have implications for traditional exchanges like Nasdaq and Cboe, which have proposed similar asset-price contracts
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