What to Know

  • Polymarket is replacing single-price settlement snapshots with time-weighted average prices for short-dated crypto markets.
  • Five-minute markets will use a 30-second average, while 15-minute and four-hour markets will use a 60-second average.
  • The new data framework will be delivered through Chainlink Data Streams.
  • Research into five-minute bitcoin contracts identified 821 accounts that made $8.2 million in settlement windows classified as likely manipulated.
  • The study found unusual large Binance orders in the final seconds before settlement, followed by fast bitcoin price reversals.
  • The researchers did not prove intent or establish that the same traders placed both the spot-market orders and the Polymarket positions.
  • Excluding market makers, 93% of losses in windows classified as manipulated fell on retail traders.
  • Polymarket said it is adding $1M in liquidity rewards across impacted markets through the month of August.
  • Kalshi uses a regulated CF Benchmarks price index and a 60-second moving average, a model that resembles the safeguards now being adopted by Polymarket.

Polymarket Changes How Short-Dated Crypto Markets Resolve

Polymarket is moving away from instant settlement snapshots for its short-dated crypto markets, introducing time-weighted average prices in an effort to reduce the impact of sudden, artificial price moves near contract expiration. The change follows months of public criticism from traders and onchain analysts, as well as academic research that identified patterns consistent with manipulation in five-minute bitcoin markets.

The platform said the update is intended to protect market integrity in its crypto up/down markets. Under the revised framework, five-minute markets will be resolved using a 30-second average, while 15-minute and four-hour markets will use a 60-second average. Polymarket said Chainlink Data Streams will provide the pricing data used in the new system.

The shift is important because short-dated prediction markets can be highly sensitive to the final reference price used for settlement. When a contract resolves based on a single price at a specific instant, even a brief move in the underlying asset can determine whether one side wins and the other loses. In markets tied to bitcoin, where deep liquidity often helps stabilize pricing but rapid bursts of trading can still create short-lived dislocations, that structure can become a focal point for aggressive traders.

Why Single-Price Snapshots Became a Concern

The core concern is structural. An asset-price contract settles on a financial price, and that financial price can sometimes be influenced by trading the underlying market itself. If a trader holds a large position on a prediction market and can move the reference market during the settlement window, even briefly, the trader may benefit from a contract outcome that would not have occurred under a broader price measure.

Researchers from Stanford University and Singapore Management University examined roughly two months of five-minute bitcoin contracts and found repeated patterns involving unusually large Binance orders in the final seconds before settlement. Those moves were often followed by rapid reversals in bitcoin, suggesting that the price pressure may have been temporary rather than driven by a lasting shift in market value.

The study did not prove that traders acted with manipulative intent. It also did not directly establish that the same people who traded on Binance were the same people holding Polymarket positions. However, the observed patterns were significant enough to intensify scrutiny of the market design. The researchers identified 821 accounts that made $8.2 million in settlement windows they classified as likely manipulated.

The retail impact was another point of concern. Excluding market makers, 93% of the losses in windows classified as manipulated fell on retail traders. For a platform built around public participation in event-based markets, that finding raised uncomfortable questions about whether the rules gave sophisticated participants an edge at the expense of smaller users.

The Five-Second Trade That Exposed the Risk

The controversy centered on the idea that a trader could accumulate a large position on Polymarket and then attempt to influence the price on Binance during the narrow settlement window. On five-minute contracts, even a few seconds could matter if the market resolved using a single snapshot. Traders and analysts described situations where a contract that appeared near-certain could flip in the final moments after a sharp move in the underlying bitcoin market.

Some chart watchers had already highlighted precise reversals in the final seconds of Polymarket’s five-minute bitcoin market before the academic study added more formal evidence. One pseudonymous onchain analyst raised detailed concerns dated May 21, while an Axis Robotics contributor using the name 郡主Christine on X noted on May 11 that the issue appeared to be becoming more severe.

Responding to those concerns at the time, Polymarket developer Josh Stevens said the team was looking more deeply into the matter. The platform’s latest rule change indicates that Polymarket now sees the settlement design itself as requiring modification, even as questions around individual trader intent remain unresolved.

How TWAP Is Meant to Reduce Manipulation Risk

A time-weighted average price, commonly shortened to TWAP, smooths the settlement value across a defined period rather than relying on a single instant. That makes it more expensive and more difficult for a trader to alter the final result with one sudden burst of spot-market activity. Instead of moving the price for a moment, a trader would need to sustain the distortion across the relevant averaging window.

For Polymarket, the chosen windows are short but still materially different from a single-price snapshot. A 30-second average for five-minute markets reduces the influence of last-second prints, while 60-second averages for 15-minute and four-hour markets add an additional layer of smoothing. The approach does not eliminate all market-impact risk, but it can make brief distortions less decisive.

Chainlink Data Streams will be used to deliver the pricing inputs, bringing an oracle infrastructure component into the new settlement process. In crypto markets, oracle design is critical because contracts often depend on external price data. If the data reference is too narrow, too delayed, or too easy to influence, settlement integrity can come under pressure.

Polymarket also said it is adding $1M in liquidity rewards across impacted markets through the month of August. That incentive appears designed to support participation during the transition, as traders adjust to the new settlement methodology and market makers reassess pricing around the updated rules.

Kalshi Comparison Highlights Industry-Wide Debate

The issue is not limited to Polymarket. Rival prediction market Kalshi has also been pulled into broader debate about how crypto-linked contracts should settle. A Kalshi developer using the name IcoBeast.eth said the problem does not exist on Kalshi, while another user responded that they had seen similar activity there.

Kalshi has emphasized differences in its structure. The platform uses a regulated CF Benchmarks price index and says all traders are identity-verified, which can make suspicious activity easier to investigate. Kalshi also uses a 60-second moving average based on regulated exchanges, a safeguard the company says makes brief attempts to move a price significantly harder and more expensive than on platforms that use instant snapshots.

Kalshi has acknowledged that offshore markets can affect prices. It has also said that arbitrageurs tend to correct artificial moves quickly. The company said it has conducted 150 to 250 material investigations per quarter and made about 40 to 50 referrals to the Commodity Futures Trading Commission so far this year. Those figures are company-wide and are not limited to short-dated crypto markets.

The comparison underscores a broader market-design challenge for prediction platforms. Crypto assets trade continuously across global venues, and price formation can be fragmented across exchanges with different rules, liquidity conditions, and participant bases. For prediction markets that settle on crypto prices, robust methodology matters as much as user interface, liquidity, or headline market variety.

Market Integrity Becomes a Competitive Issue

For Polymarket, the new TWAP system is both a technical adjustment and a reputational test. Prediction markets rely on user confidence that outcomes are resolved fairly. If traders believe the final seconds of a contract can be gamed by larger players, participation may become skewed toward those willing or able to influence settlement conditions.

The use of TWAP does not guarantee that every dispute will disappear. Market participants may still debate the proper length of averaging windows, the best data sources, and whether different contract durations require different protections. Still, moving from a single-price snapshot to an averaged settlement price directly addresses the specific vulnerability highlighted by traders and researchers.

The stakes are especially high in very short-dated crypto markets, where the difference between a fair wager and a contest of microstructure power can be narrow. As prediction markets expand, platforms are likely to face more pressure to demonstrate that their rules can withstand sophisticated trading strategies, cross-market pressure, and sudden liquidity bursts.

FXCOINZ views the Polymarket update as part of a broader maturation phase for crypto-linked prediction markets. The sector is moving beyond simple product growth and into questions of surveillance, data integrity, settlement design, and trader protection. In that environment, platforms that can make manipulation more expensive without damaging liquidity may gain an advantage.

Frequently Asked Questions (FAQs)

What did Polymarket change in its crypto markets?

Polymarket replaced single-price settlement snapshots with time-weighted average prices for short-dated crypto markets. The goal is to reduce the impact of sudden price moves that occur immediately before settlement.

What is a TWAP?

TWAP stands for time-weighted average price. Instead of using one price at one instant, it averages prices over a set window, making brief distortions less likely to decide a market outcome.

How will Polymarket settle five-minute crypto markets now?

Five-minute crypto markets on Polymarket will use a 30-second average. That means the settlement result will be based on pricing across that short window rather than a single final snapshot.

What settlement windows will apply to longer markets?

Polymarket said 15-minute and four-hour markets will use a 60-second average. This gives those markets a broader pricing window than the five-minute contracts.

Why were traders worried about manipulation?

Traders and researchers raised concerns that large orders on Binance in the final seconds before settlement could push bitcoin prices just enough to change Polymarket outcomes, especially in five-minute contracts.

Did researchers prove manipulation happened?

The research did not prove trader intent or directly establish that the same people traded on Binance and held Polymarket positions. It identified patterns consistent with likely manipulation and found significant retail losses in those windows.

How much profit was linked to likely manipulated windows?

The researchers found that 821 accounts made $8.2 million in settlement windows classified as likely manipulated. Excluding market makers, 93% of losses in those windows fell on retail traders.

Polymarket said Chainlink Data Streams will deliver the pricing data used for the new time-weighted settlement process. Reliable data delivery is important because these contracts depend on external market prices.

How does Kalshi approach similar risks?

Kalshi uses a regulated CF Benchmarks price index and a 60-second moving average. The company says this makes brief attempts to move settlement prices harder and more expensive than instant snapshot systems.

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