A new study suggests traders may be manipulating Polymarket’s five-minute Bitcoin bets to swing wagers their way.

Researchers at Stanford University and Singapore Management University said they examined roughly 16,000 of Polymarket’s five-minute Bitcoin contracts for two months, finding signs that traders may have been manipulating spot price on Binance.

“In the final seconds before settlement, Binance spot order flow spikes, resulting in price movements that revert shortly after settlement,” the paper reads. “Clearly, this is a transitory push to manipulate the spot price, not trading on information.”

Research faults Binance over Polymarket’s manipulation

Polymarket uses a Chainlink oracle for its five-minute contracts, which takes the average BTC price across major spot exchanges. However, the researchers said Binance was “an economically tight proxy” for the oracle pricing, considering its volume.

Binance’s mid price stays extremely close to the oracle such that “a push that drives the Binance mid a few basis points past the strike reliably carries the resolution,” the researchers said, adding that contract finishes on the same side as Binance 85% of the time.

The study suggested other trading platforms offering similar contracts could face the same vulnerability, not just Polymarket, because of how the bets resolve.

“These contracts have a structural vulnerability,” one of the paper’s authors said. “They settle on a price that traders can move by trading the underlying asset itself.”

Polymarket responds to bet manipulation concerns

Speaking on the findings, a spokesperson for Polymarket said the platform is looking to change some of its market to settlement methods that use prices over a longer period rather than a single point in time, in the coming year.

Polymarket has previously been in the news for manipulation concerns.

Last year, a Columbia University study found that 25% of Polymarket’s trading activities over the past three years were artificial and arranged through wash trading, Cryptopolitan reported.

In March 2026, Polymarket tightened its market integrity rules across its CFTC-regulated US exchange and DeFi platform. The new rules cover the firm’s market design standards, resolution criteria, and data sourcing requirements.

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