Polymarket reforms Bitcoin contracts and Binance trading spikes immediately drop
Polymarket's Bitcoin contracts now use averaged opening and closing benchmarks instead of single snapshots, following an August reform that appears to have reduced trading manipulation patterns.
Polymarket's five-minute Bitcoin contract, sampled on Oct. 27, now uses averaged opening and closing benchmarks following an August reform that changed the incentive to move its settlement price. The current design requires a different risk assessment from the single-snapshot rule examined in earlier research.
Historical research estimated about $8.2 million earned by 821 wallets in earlier pushed cycles. However, Guangzhe Wang's newer study shows a subsiding Binance trading pattern in the first weeks after averaging was implemented.
Trading patterns change
The Oct. 27 Bitcoin market, covering 12:20-12:25 p.m. ET, names Chainlink's BTC/USD 60-second time-weighted average price (TWAP) as its resolution source. Up wins when the ending benchmark is at least as high as the opening benchmark, and Down wins otherwise.
Wang's paper examined Binance one-second data from July 1, 2025, through Sept. 4, 2026, with 82,752 Bitcoin boundaries where only the five-minute contract settled. For each sampled five-minute window, he measured the share of Binance volume traded in its final ten seconds.
In the first three weeks of the 60-second regime, Wang found no systematic migration into earlier bins and no recurrence of the earlier near-strike reversal pattern.
How the averages work
According to Polymarket's changelog, crypto up/down markets switched from single snapshots to Chainlink-computed averages on Aug. 7. Both the opening price to beat and the final settlement value moved to the applicable TWAP feed.
On Aug. 14 at 00:00 UTC, the platform extended five-minute crypto markets to 60 seconds. The October contract reflects an operating rule introduced more than two months earlier, and its five-minute duration should not be confused with its one-minute benchmark window.
Under a snapshot rule, an unusually brief move can be important if it affects the selected reference price. Under an average, its contribution depends on how much of the measurement window it influences.
Remaining questions
The study tests an observed response to the reform, and its outcome is a trading pattern. It is neither a current wallet-profit audit nor proof that every possible manipulation strategy has disappeared.
Polymarket's documentation says it takes the applicable average, just as it does for the closing value. Evaluating a disputed result requires the reference values used at both boundaries, along with the relevant report timing.
The remaining measurement is financial as well as behavioral: gains and losses under the averaged rule, with the relevant underlying-market trades and execution costs accounted for. Complete analysis would need to determine whether the benefit on the prediction-market position exceeds the cost of affecting that average and executing the strategy.
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