Debate erupts over the 10,000 USD NASCAR prediction market on Polymarket

A prediction market worth 10,000 USD on Polymarket for the NASCAR Cup Series race taking place on Sunday has unexpectedly become one of the biggest controversies in UMA's history, after the platform's oracle rejected an early closing proposal, despite it being accurate.

According to a user named Domer posted on July 24, this confrontation has raised questions about how UMA's optimistic oracle ( balances speed, clarity, and fairness.

How a 10,000 USD market became a 60,000 USD battle

When the checkered flag ended the race at 6:58 PM ET ), which is equivalent to 5:58 AM Vietnam time (, Denny Hamlin crossed the finish line first and was later confirmed as the winner after NASCAR's post-race inspection.

Just a minute after the race ended, a veteran trader on Polymarket nicknamed "GeopoliticsWizard" submitted 40 settlement proposals to UMA — each proposal representing a bet contract for each racer — and deposited a collateral amount of 750 USDC for each proposal.

About 90 minutes later, other users opposed all 40 proposals, arguing that the sender did not wait for the post-race check results. According to UMA's rules, each opposition also requires a deposit equivalent to 750 USDC.

As a result, with 40 proposals and 40 oppositions, the total amount of bets has ballooned to 60,000 USD, six times the size of the initial prediction market. The distribution method has been predetermined: the winning side will receive the entire 40 deposits )40.000 USD(, while UMA retains the remaining 20,000 USD as protocol revenue.

UMA's public documentation does not require the proposer to wait for post-race verification results. Instead, UMA instructs users to use a "publicly authoritative source."

The official NASCAR ranking at that time had no notes or asterisks, but nonetheless, the on-chain voters assessed the proposals as "too early" )Too Early( and agreed with the opponents. The vote took place after NASCAR confirmed Hamlin's victory at 8:26 PM, and the objections were submitted just one minute later, at 8:27 PM.

This ruling wipes out nearly the entire net profit of 30,000 USD of the proposer, turning a previously profitable account into a loss, according to Domer's sharing.

How UMA Works

UMA uses a three-step mechanism: "proposal - opposition - voting". Anyone can submit a final answer along with a deposit. If the answer is not opposed during its short "life" period, it becomes official.

A opposing party can submit a corresponding deposit to trigger a vote from UMA token holders. The majority side will receive both deposits, while the minority side will lose their submitted deposit.

This model is designed to be fast and decentralized, but the incident related to the NASCAR race shows that costs can far exceed the nominal value of the market as disputes escalate.

Earlier in July, UMA was criticized for a contract worth 200 million USD on Polymarket betting on whether Ukrainian President Volodymyr Zelensky would wear a "suit" or not.

Initially, UMA concluded "Yes", but after being challenged on the definition of what "suit" is, they reversed the result, showing that ambiguous language can cause serious issues for the oracle.

A few days later, another prediction market for the MLB baseball game also awarded the wrong winning team. UMA stated that the reason was a technical error and no one objected, while promising to refund.

Overview

According to Domer, the incident involving NASCAR reveals a deeper issue: the UMA voting body is increasingly narrowing down to a small "inner circle" of individuals who are financially motivated and often side with the opposition rather than being objective to the truth.

When Polymarket itself maintains a neutral stance ) as in this case (, UMA relies on "insiders" to decide, and they often follow a certain direction.

Domer said additionally:

"The current voting system is more centralized than ever, with an almost inactive community... The opposing group has spammed Discord heavily, so the result must be 'Too Early', and UMA voters did exactly as they were asked."

Domer concludes that such incentives are turning legitimate traders into collateral victims.

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