Polymarket Mispricing Events
Detects and trades mispricings on Polymarket by comparing market prices against a consensus probability estimated from Kalshi and Manifold using fuzzy title matching.
Strategy
- Fetches all active Polymarket binary markets (top 500 by liquidity)
- For each market, searches Kalshi and Manifold for the same event via Jaccard title similarity
- Computes weighted consensus probability (Kalshi 55%, Manifold 45%)
- Enters if gap between consensus and Polymarket price exceeds threshold (default 15%)
- Sizes position with quarter-Kelly criterion, capped between $5 and $50
- Skips markets with flip-flop warnings, high slippage, or insufficient edge
Edge
Cross-platform prediction market arbitrage. When two independent markets disagree by 15%+ on the same event, one of them is wrong. This skill bets on the consensus.
When it works best
- Political, macro, and sports markets with active Kalshi/Manifold counterparts
- Events with clear resolution criteria
- Markets in the 15%-85% probability range (not near-resolved)
Configuration (env vars)
| Variable | Default | Description |
|---|---|---|
| SIMMER_API_KEY | required | Your Simmer API key |
| TRADING_VENUE | sim | sim for paper, live for real money |
| EVENTS_ENTRY_THRESHOLD | 0.15 | Minimum gap to enter (15%) |
| EVENTS_KELLY_FRACTION | 0.25 | Kelly multiplier (0.25 = quarter-kelly) |
| EVENTS_TRADE_SIZE_MIN | 5.0 | Minimum trade size in USD |
| EVENTS_TRADE_SIZE_MAX | 50.0 | Maximum trade size in USD |
| EVENTS_MAX_POSITIONS | 8 | Maximum open positions |
| EVENTS_MIN_LIQUIDITY | 500.0 | Minimum market liquidity |
| EVENTS_MAX_GAP_CAP | 0.35 | Reject gaps > 35% (model likely wrong) |
Risk
- Cross-platform matching via fuzzy text can produce false positives — keep position sizes conservative
- Rare markets may have no Kalshi/Manifold counterpart — these are skipped
- Kelly sizing still carries variance risk; recommend starting with sim venue