Last month, Garrick Wilhelm jumped into prediction market trading, but he soon began to regret it. The resident of British Columbia, Canada, signed up on the Polymarket platform and started placing bets on events related to the Middle East, including one wager on whether Israel and Hezbollah would reach a ceasefire agreement.
Wilhelm bet $567 on a loss, believing the armed group could never sign a ceasefire agreement, calling it a sure thing.
Subsequently, if Israel and the Lebanese government reach a ceasefire agreement, some traders interpret this as equivalent to a truce with Hezbollah. After carefully reviewing the platform’s rules, Wilhelm firmly disagrees with this interpretation.
The outcome of this bet involving millions of dollars was not determined by the Polymarket platform. Wilhelm only then learned that the resolution of his trade was decided by a loosely organized group of individuals holding cryptocurrency tokens.
As new users flood in and trading volume surges, dispute resolution has become an increasingly challenging issue for prediction market platforms like Polymarket. Although these platforms aim to frame betting topics as clear, binary questions, real-world events are often complex, making outcomes difficult to definitively determine.
Like most other prediction market platforms such as Kalshi, Polymarket outsources dispute resolution to a third-party service provider, UMA. When parties disagree on payout outcomes, the UMA voting mechanism is triggered, with voting power held by UMA token holders—those with larger token holdings have greater voting weight, and the vast majority of voters remain anonymous.
Polymarket explicitly states in its User Agreement that the platform assumes no responsibility for resolving disputes related to trading contracts.
Many traders and seasoned crypto industry insiders have直言 that this UMA voting system is highly susceptible to fraud. Token holders can freely vote on disputes in which they have a personal stake, with no institutional constraints.
The Wall Street Journal, combining Polymarket trading data with on-chain information, found that at least 60% of active UMA voters over the past year could be linked to Polymarket trading accounts; in all over 300 dispute cases during the same period, UMA voters held positions in the disputed betting markets.
UMA markets itself as decentralized, but on-chain data shows that voting power is highly concentrated among a few large holders. Statistics indicate that in the vast majority of dispute votes, the top ten wallet addresses account for more than half of the total votes.
Nic Carter, co-founder of venture capital firm Castle Island Ventures, bluntly stated that Polymarket should not shirk its responsibility for dispute resolution. “Resolving disputes is inherently Polymarket’s duty—it should not be outsourced to anonymous third-party token holders whose identities are unknown.”
A spokesperson for Polymarket stated that only 0.2% of betting contracts on the platform trigger UMA voting resolutions, and added that UMA decentralizes decision-making authority to the open market system rather than entrusting it to a single entity.
In March this year, Polymarket founder Shayne Coplan acknowledged at a Harvard Business School panel that the platform’s current dispute resolution mechanism has significant vulnerabilities. “Optimizations are imminent,” he said, without disclosing specific details of the changes. It is reported that Polymarket has entered into a data partnership with Dow Jones, the parent company of The Wall Street Journal.
UMA was co-founded by two former Goldman Sachs traders and is managed by the Risk Labs Foundation, registered in the Cayman Islands. A spokesperson for the foundation, James Fry, stated that no concrete evidence has been found indicating that the UMA platform manipulates trades. “Most of the external skepticism is simply traders who have lost bets looking for excuses.”
In the event of a dispute, UMA token holders engage in discussions on the Discord social platform, citing various supporting materials to substantiate their positions. Additionally, UMA has a penalty mechanism that imposes economic sanctions on users who vote with the minority opinion, a measure the platform claims is designed to encourage voters to make accurate, fact-based decisions.
According to Betmoar, Polymarket’s exclusive trading terminal, over 1,150 betting disputes have occurred on the platform since 2026, surpassing the total number for all of 2025.
Another recent hotly debated betting market centered on streamer Clavicular’s official announcement of preparing for pregnancy: although the streamer did publicly announce that their partner is pregnant, many traders argued that this announcement did not meet the contract’s definition of a “formal valid statement.” Ultimately, UMA voting determined that this announcement was compliant. Additionally, multiple ruling discrepancies have emerged in bets related to the situation in Iran.
Public regulatory filing documents show that Polymarket initially handled all disputes internally; in early 2022, the platform reached a settlement with the U.S. Commodity Futures Trading Commission over alleged violations of U.S. financial regulations, and since then has fully delegated dispute resolution to UMA.
The model of decentralized token holder governance also serves as Polymarket’s key justification for positioning itself as an offshore platform not subject to U.S. regulatory oversight.
However, Polymarket occasionally overrides UMA’s final rulings and provides additional clarifications on bet contract terms in advance to avoid potential disputes.
As mentioned earlier, novice trader Wilhelm ultimately lost his bet related to the ceasefire agreement, as 87% of UMA token voters determined that the Israel-Lebanon ceasefire applied to the Hezbollah-related wager. Despite Wilhelm and other parties presenting their arguments, the ruling could not be overturned.
A group of losing traders formed a Discord community called "Whale Hunters" to collectively denounce suspected backroom dealings by top UMA voting users.
Traders have targeted the startup project UMA.rocks, a platform that enables UMA token holders to consolidate their voting power and delegate voting rights to a specialized decision committee. In recent contentious votes, UMA.rocks accounted for 8% of the total votes and is regarded by the market as a key indicator of UMA’s overall governance direction.
Lancelot Chardonnet, founder of UMA.rocks, responded: "Many traders lose money simply because they didn't carefully read the betting rules, yet they blame UMA and our platform entirely afterward—we are the easiest target."
At the end of April, UMA.rocks officially removed Scout from the voting committee due to suspected market manipulation in their past actions.
The journalist reached out to Scout via Discord, who denied manipulating the market or deliberately influencing incorrect voting outcomes, but openly admitted to placing bets on the Polymarket dispute while simultaneously exercising his UMA dispute resolution voting rights.
Scout believes that voting participants with a vested interest in the outcome are more likely to reach a ruling that aligns with the facts. “Voters with no stake in the matter may spend just five minutes superficially reviewing the situation; as traders holding positions, we have a financial incentive to thoroughly investigate the full context and make an accurate judgment.”
He admitted that the industry is caught in a dilemma: “Either involve traders with conflicts of interest in decision-making, or let uninformed outsiders dominate the voting—there is currently no perfect solution.”