Polymarket vs. Sportsbook Odds Discrepancy — Sports Market Mispricing

How It Works The scanner fetches real-time sportsbook odds from ESPN (no API key required) and converts them to implied probabilities, then compares those against Polymarket's current market prices for equivalent sports outcomes. Discrepancies beyond a defined threshold (5%+) are flagged as tradeable signals.

Entry Conditions A trade signal is generated when Polymarket's implied probability diverges from the sportsbook-implied probability by 5% or more. NHL markets are specifically identified as systematically overpriced by 10–17%, suggesting a structural inefficiency potentially driven by unsophisticated retail flow.

Exit Conditions Given these are binary sports outcome markets, positions are likely held to resolution. No dynamic exit logic is described.

Verified Results The repo claims a 100% win rate on signals with 5%+ edge and a 10–17% systematic edge on NHL markets. These are strong claims but come without auditable on-chain data or sample size disclosure, significantly limiting their credibility.

Implementation Notes & Risks The primary risk is that ESPN odds represent sharp sportsbook consensus and may be more accurate than Polymarket, but sportsbook odds include vig that must be stripped before comparison. Data freshness is critical — stale ESPN data during live games could produce false signals. The 100% win rate claim without sample size is a major red flag for overfitting or cherry-picking.