NegRisk Multi-Outcome Complete-Set Arbitrage

How It Works Polymarket's NegRisk mechanism allows multi-outcome markets where buying one share of every outcome (a 'complete set') should cost exactly $1.00. If the sum of all outcome prices deviates above or below $1.00 by more than transaction costs, an arbitrage exists. The scanner continuously monitors these deviations across all active NegRisk markets.

Entry/Exit Conditions When the sum of outcome prices exceeds $1.00 by a meaningful margin (accounting for gas and spread), the bot sells the overpriced complete set (or buys the underpriced side). When prices deviate below $1.00, the bot buys all outcomes simultaneously. The position resolves naturally at market settlement for a guaranteed profit, or is closed early if prices converge.

Verified Results The repository claims 60 passing automated tests and includes a live browser demo, suggesting a production-grade implementation. Paper-trading mode is available. No specific PnL or on-chain trade history is referenced, but the technical rigor (asyncio, test suite, demo) is notably higher than most repos in this report.

Implementation Notes Built in Python using asyncio for concurrent market scanning. The repo explicitly targets NegRisk markets, which are Polymarket's categorical multi-outcome structure. Production-grade framing with paper-trading mode for safe initial deployment. The test suite (60 tests) provides meaningful confidence in implementation correctness.

Risks Complete-set arbitrage requires simultaneous execution across all outcomes — partial fills leave residual directional risk. Liquidity may be insufficient to fill all legs at quoted prices. Gas costs on Polygon and Polymarket fees can compress or eliminate the spread. Market resolution disputes or delays introduce settlement risk.