Polymarket reforms Bitcoin contracts, Binance trading pattern subsides

The mechanism for calculating outcomes on Polymarket’s five-minute Bitcoin contracts, which utilized averaged opening and closing benchmarks, is a direct result of an August reform that altered how the settlement price is determined. This updated design necessitates a different approach to risk assessment compared to the single-snapshot methodology examined in prior research.

A more recent investigation by Guangzhe Wang, which references findings from Dai and collaborators, indicates that the trading activity observed on Binance in the initial weeks following the adoption of averaging has diminished. This provides an empirical test for the reform, while simultaneously leaving open the questions regarding whether the settlement-time pattern has lessened and precisely how much traders incur under the current framework.

The October 27 Bitcoin market, which spanned from 12:20 to 12:25 p.m. ET, used Chainlink’s BTC/USD 60-second time-weighted average price (TWAP) as its source for resolution. A bet wins "Up" if the concluding benchmark is equal to or higher than the starting benchmark, whereas a "Down" bet prevails otherwise.

The initial work by Dai, Jia, and Yu, presented as a working paper on arXiv on June 30, detailed spikes in spot-flow and subsequent reversals occurring at settlement times after the five-minute contract was introduced. This broader observation pertained to the incentive to influence the underlying market reference.

Wang’s newer paper analyzed Binance's one-second data spanning from July 1, 2025, until September 4, 2026, focusing on 82,752 Bitcoin intervals where only the five-minute contract settled. For every sampled five-minute period, he quantified the portion of Binance volume exchanged during its final ten seconds. In the initial three weeks of the 60-second system, Wang observed no systematic shift toward earlier time bins and no repetition of the earlier pattern of reversal near the strike price. This limited observation aligns with the reform proving effective against the specific pattern measured.

It is important to note that this study does not constitute a current audit of wallet profits, nor does it confirm that every conceivable method of manipulation has been eliminated. The research evaluates a reaction to the reform, and its conclusion pertains to a trading pattern.

According to Polymarket’s official changelog, crypto up/down markets transitioned from using single snapshots to Chainlink-computed averages on August 7. Both the opening price that needed to be beaten and the final settled value were moved to the relevant TWAP feed. Furthermore, on August 14 at 00:00 UTC, the platform extended its five-minute crypto markets to a 60-second duration.

The contract from October reflects an operational rule implemented over two months prior, and its five-minute duration should not be mistaken for its one-minute benchmark window. Under the former snapshot rule, a very brief movement could hold significance if it impacted the chosen reference price. In contrast, under an averaging system, its impact depends on the extent to which it influences the measurement period. The core economic inquiry revolves around whether the advantage gained from the prediction-market position outweighs the expense of altering that average and executing the corresponding strategy.

Without evidence that the previous behavior and economics remain applicable, a historical dollar gain cannot be directly transferred into this altered calculation.

Polymarket’s documentation clarifies that it utilizes the applicable average for the closing value, just as it does for the closing value. To properly assess a disputed outcome, the reference values present at both boundaries, alongside the pertinent reporting time, must be examined. Chainlink’s timestamp documentation explains that the time displayed on an exchange chart is insufficient for complete analysis. Each underlying report possesses a start validity and an observation timestamp, but the report durations can vary, including instances where a subsequent report incorporates a gap.

The TWAP weights prices according to the length of time they cover. Moreover, the average adjusts with the most recent observation rather than rigidly snapping to a precise minute mark. Consequently, a 60-second TWAP is not equivalent to the average price across the entire five-minute wager, nor is it necessarily sixty ticks given equal weight.

A profit on a prediction-market position is a different metric than the net return generated from a strategy involving the actual underlying asset. If manipulating Bitcoin’s reference price demands trading Bitcoin, that transaction and its associated execution costs must be factored into the profitability assessment.

The Polymarket Institute differentiates between the decentralized international exchange and Polymarket US, maintaining separate APIs and independently managed data. Talos’s quarterly review for October 27 highlights its integration with Kalshi and references earlier analyses concerning potential manipulation of Polymarket settlements. The remaining assessment is multifaceted, involving both financial and behavioral aspects: gains and losses under the averaged rule, with the relevant trades in the underlying market and their execution costs taken into account.

Liam Wright, who serves as a reporter, podcast producer, and Editor-in-Chief at CryptoSlate, is also known as "Akiba," and he believes that decentralized technology holds the potential to make… Gino Matos, a journalist with six years of industry experience and a law school background, focuses his expertise primarily on the Brazilian blockchain sector.

Why it matters

This shows the empirical effect of Polymarket's contract changes on market behavior, moving away from single-snapshot rules. Readers should watch how these new averaged rules affect profitability calculations compared to historical gains.