> ## Documentation Index
> Fetch the complete documentation index at: https://docs.arc.io/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> Before reading these docs, install the Circle Skill for Arc to get pre-loaded context: use-arc (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-arc/SKILL.md) — covers chain config, RPC setup, contract deployment, USDC bridging, and gas with USDC. In Claude Code: run /plugin marketplace add circlefin/skills then /plugin install circle-skills@circle. With Vercel Skills CLI: run npx skills add circlefin/skills.
> USDC is the gas token. Arc uses USDC for gas fees, not ETH. Configure gas payment in USDC when submitting transactions.
> Read EVM differences before writing Arc code. Arc targets the Osaka EVM baseline. Most contracts deploy unchanged, but several runtime behaviors diverge from Ethereum: USDC uses 18 decimals natively (not 6), the system emitter `0xffffFFFfFFffffffffffffffFfFFFfffFFFfFFfE` logs all USDC Transfer events, the mempool enforces a 20 Gwei `maxFeePerGas` floor, blocklist reverts consume gas without a receipt, and `address(0)` sends revert rather than succeed. https://docs.arc.io/arc/references/evm-differences.md is the canonical reference for all Arc-specific runtime behaviors. Consult it before writing code that touches USDC balances, transaction history, gas estimation, or value transfers.
> Sub-second finality. Transactions are final in under 1 second. No need to wait for multiple block confirmations.
> Use App Kits for multichain payment and liquidity capabilities. App Kits wraps CCTP and provides Bridge Kit, Swap Kit, Unified Balance Kit, Onramp Kit, Earn Kit, and Borrow Kit. Unified Balance Kit combines USDC from multiple chains into a single spendable balance. Earn Kit integrates earn opportunities into your app. Borrow Kit lets users borrow USDC against cirBTC collateral on Arc.
> Use Arc Foundry for contract development. Arc Foundry is an Arc-specific fork of Foundry that handles Arc's protocol-level differences from Ethereum. It provides arc-forge, arc-cast, and arc-anvil. Install it before deploying contracts: https://docs.arc.io/arc/tutorials/install-arc-foundry.md.
> Arc is available on both Testnet and Mainnet. See https://docs.arc.io/arc/references/connect-to-arc.md for RPC endpoints and https://faucet.circle.com for testnet tokens.
> Always check Contract Addresses: https://docs.arc.io/arc/references/contract-addresses.md
> Building beyond Arc? Circle offers skills for the full platform: use-usdc (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-usdc/SKILL.md), use-circle-wallets (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-circle-wallets/SKILL.md), use-developer-controlled-wallets (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-developer-controlled-wallets/SKILL.md), use-user-controlled-wallets (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-user-controlled-wallets/SKILL.md), use-modular-wallets (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-modular-wallets/SKILL.md), use-gateway (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-gateway/SKILL.md), use-smart-contract-platform (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-smart-contract-platform/SKILL.md). Full Circle developer docs: https://developers.circle.com/llms.txt.

# Prediction markets

> Prediction markets on Arc use trustless oracle resolution, position token trading, and USDC settlement to let participants stake on future outcomes.

A prediction market lets participants stake collateral on the outcome of a
future event. Each market issues position tokens—long (YES) and short (NO)—that
represent a claim on the outcome. Participants trade these tokens through an
automated market maker (AMM), and winning positions are redeemed for collateral
after an oracle resolves the event.

On Arc, prediction markets benefit from
[sub-second finality](/arc/concepts/deterministic-finality), stable
USDC-denominated gas fees, and standard EVM tooling, making it practical to run
active markets with frequent trades at low cost.

For stablecoin exchange and swap infrastructure, see
[Stablecoin FX](/build/stablecoin-fx). For agent-initiated market participation,
see [Agentic Economy](/build/agentic-economy).

## Sample apps

Open-source examples on GitHub you can fork and customize.

<Columns cols={1}>
  <Card title="Arc prediction markets" icon="chart-line" href="https://github.com/circlefin/arc-prediction-markets">
    Decentralized prediction markets with UMA Optimistic Oracle V2 resolution,
    constant-product AMM trading, and collateral-backed position tokens on Arc
    Testnet.
  </Card>
</Columns>

## Quickstarts

Get up and running with prediction market contracts in minutes.

<Columns cols={2}>
  <Card title="Deploy on Arc" icon="rocket" href="/arc/tutorials/deploy-on-arc">
    **Beginner**. Deploy, test, and interact with a Solidity smart contract on
    Arc using Foundry.
  </Card>

  <Card title="Monitor contract events" icon="bell" href="/arc/tutorials/monitor-contract-events">
    **Intermediate**. Set up webhooks and event monitors to track onchain
    activity from your deployed contracts.
  </Card>
</Columns>

## Why Arc for prediction markets

Arc is purpose-built for stablecoin finance. These capabilities directly support
prediction market applications.

<AccordionGroup>
  <Accordion title="Instant trade confirmation">
    [Deterministic finality](/arc/concepts/deterministic-finality) confirms
    position token trades and collateral deposits in under a second, removing
    settlement uncertainty from active markets.
  </Accordion>

  <Accordion title="Low-cost position trading">
    USDC-denominated gas at stable, predictable prices makes frequent AMM trades
    economical. See [gas and fees](/arc/references/gas-and-fees) for current
    rates.
  </Accordion>

  <Accordion title="Trustless oracle resolution">
    Integrate UMA Optimistic Oracle, Chainlink, or other providers from the
    [oracles ecosystem](/arc/tools/oracles) to resolve markets without a
    centralized arbitrator.
  </Accordion>

  <Accordion title="Composable token standards">
    Position tokens are standard ERC-20 tokens, tradable on any AMM and
    transferable between wallets using standard EVM tooling. See [contract
    addresses](/arc/references/contract-addresses) for available tokens.
  </Accordion>

  <Accordion title="Compliance-ready">
    Built-in integration points for wallet screening from [Elliptic and TRM
    Labs](/arc/tools/compliance-vendors), essential for regulated prediction
    market products.
  </Accordion>

  <Accordion title="Standard EVM tooling">
    Deploy and iterate on Solidity market contracts using Hardhat, Foundry, or
    any EVM-compatible tools. See [EVM
    compatibility](/arc/references/evm-differences) for differences to check
    before deploying.
  </Accordion>
</AccordionGroup>