Researchers say a few basis points of pressure on Binance is usually enough to carry the resolution, and put the cost to ordinary traders at about $1.28 million.

Polymarket's five-minute Bitcoin contracts pay traders to push the spot market around at the moment of settlement, according to a study by academics at Stanford University and Singapore Management University, letting better-informed participants take gains out of retail traders' pockets.

The contracts are simple wagers on whether Bitcoin will be trading above or below a chosen level five minutes after the bet is placed.

The incentive comes from how the wagers resolve. Polymarket's five-minute Bitcoin markets settle on a Chainlink oracle that blends quotes from leading spot venues into an average, taken as each five-minute window closes — a single number that traders have reason to nudge in the seconds just before it is read.

Looking at roughly 16,000 of these markets over two months, the authors turned up indications that some traders had possibly pushed Bitcoin's spot price on Binance to tilt how contracts resolved. Order flow on Binance surges in the closing seconds before resolution, they found, and the price moves it produces unwind soon afterwards — behaviour they read as a short-lived shove rather than trading on fresh information. In windows where the betting was close to a coin flip, order flow climbed to about 3.9 times its usual volume.

Given its volume, the researchers say, Binance functions as a close proxy for the settlement oracle. Its mid price tracks that oracle so tightly, on their account, that shoving the quote a handful of basis points past the strike is enough to reliably carry the resolution, with outcomes landing on Binance's side of the line roughly 85% of the time. Across the sample, they size the wealth moving from everyday traders to manipulators at about $1.28 million.

Binance said the allegations concern a separate outside venue rather than the exchange itself, and that as the biggest and deepest crypto exchange it is frequently where prices are discovered.

Polymarket points to its use of multiple independent pricing oracles as part of what it says safeguards market integrity. Separately, the platform tightened its integrity rules in March 2026, covering both the US exchange it operates under CFTC oversight and its DeFi venue: how markets are built, what criteria settle them and where their data must come from.

One of the authors called the flaw structural: resolution rests on a price that traders can move themselves by trading the underlying asset. Lengthening contracts from five minutes to 15 wiped out most of the manipulation they measured, and the paper also floats different pricing approaches, among them prices averaged over time.

The study suggests the weakness is not confined to Polymarket: any venue running comparably brief contracts could face the same vulnerability, because of how the bets resolve. The authors point to established exchanges including Nasdaq and Cboe, which have put forward event contracts tied to asset prices — which, on their reading, puts growing weight on how such contracts are designed as prediction markets move into regulated finance.