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UMA

Live

A decentralized truth machine — UMA's Optimistic Oracle records any verifiable statement onto a blockchain.

Visit UMA
Best for
Real-world event outcomes — elections, sports, awards, news
Token
UMA Holders stake to vote on disputed outcomes
Track record
819K+ assertions · 99.55% undisputed
as of Jun 2026 · source
Used by
Polymarket Predict.fun

How it works

1
Propose
Anyone can submit an answer to a market's outcome question, along with a financial bond.
2
Challenge window
For a fixed period (usually 2 hours, up to 24 for sensitive markets), anyone can dispute the answer by posting their own bond.
3
If undisputed
The proposed answer stands; the market resolves; the proposer gets their bond back plus a small reward.
4
If disputed
UMA-token holders stake to vote on the truth. The honest side wins both bonds; dishonest stakers are slashed.

Why prediction markets use it

  • Only oracle that can settle arbitrary text outcomes — elections, sports, awards, news, geopolitics — anything a human can verify.
  • Economic incentives mean disputes are rare in practice: 99.55% of 819K+ assertions have gone uncontested (Dune dashboard, refreshed daily).
  • Has settled the largest prediction-market events of the era (2024 US election, IPL finals, geopolitical conflicts).

Used by

Polymarket
Decentralized prediction market on Polygon — USDC-settled, UMA/Chainlink/Pyth-resolved, ICE-partnered.
Predict.fun
Prediction market on BNB Chain, integrated directly inside the Binance app.

History

  1. 2018 UMA whitepaper published; project initiated under Risk Labs.
  2. 2020 UMA token launches; mainnet Optimistic Oracle goes live.
  3. 2021 Polymarket adopts UMA as primary resolution layer for binary outcomes.
  4. 2023 Optimistic Oracle v3 released with improved dispute economics.
  5. 2026-03 Predict.fun migrates text-outcome resolution to UMA.

Chains supported

Ethereum Polygon Optimism Arbitrum Base BNB Chain Avalanche

About

UMA (Universal Market Access) is a decentralized oracle protocol developed by Risk Labs Foundation. Resolution follows a 4-stage Optimistic Oracle flow: (1) a natural-language statement is submitted along with a bond; (2) anyone may dispute during the challenge period; (3) if disputed, UMA-token holders vote; (4) honest voters earn rewards while dishonest proposers / disputers forfeit their bonds. Because honest behaviour is economically rational, most statements settle uncontested. Risk Labs Foundation publicly lists Polymarket, Across, Sherlock, Story Protocol and Rated among the projects building on UMA.

Primary source
UMA — Official site + docs.uma.xyz · verified 2026-06-20