Kalshi-Polymarket Divergence Arb

Cross-platform price divergence trading between Kalshi and Polymarket.

What It Does

Polls Kalshi's public API for live prices across 13 event series and compares

them to equivalent Polymarket markets found via SimmerClient. When prices diverge

beyond threshold, the cheaper side is likely underpriced.

Covered Series

Signal Logic

• BUY - Polymarket price is >8% below Kalshi equivalent (Polymarket underpriced)
• SELL - Polymarket price is >10% above Kalshi equivalent (Polymarket overpriced)
• Asymmetric thresholds account for Polymarket's typically lower liquidity

Scheduling

Runs every 5 minutes via cron (/5 *). Managed automaton (auto-executes on schedule).

Dry-run by default. Pass --live to execute real trades.

Requirements

pip dependencies: simmer-sdk, requests

Environment variables (required):

• SIMMER_API_KEY - get from simmer.markets/dashboard

Environment variables (optional, all have defaults):

• TRADING_VENUE - defaults to sim for paper trading, set to polymarket for real
• KALSHI_BUY_THRESHOLD - minimum divergence to trigger BUY, defaults to 0.08 (8%)
• KALSHI_SELL_THRESHOLD - minimum divergence to trigger SELL, defaults to 0.10 (10%)
• KALSHI_TRADE_SIZE - trade size in USD, defaults to 20.0

Usage

python kalshi_divergence.py                  # dry run (default, no trades)
python kalshi_divergence.py --live           # real trades via SimmerClient
python kalshi_divergence.py --live --quiet   # cron mode

Trade Execution Path

1. Fetches Kalshi public prices via HTTPS GET (no auth needed)
2. Finds matching Polymarket markets via SimmerClient.find_markets()
3. Compares prices, applies thresholds (BUY >8%, SELL >10%)
4. If --live: calls SimmerClient.trade() with market_id, side, amount, reasoning
5. If dry-run (default): logs the signal but does NOT execute any trade

Security

• All trades go through SimmerClient.trade() only. No direct CLOB or wallet access.
• Only required credential is SIMMER_API_KEY. No other secrets needed.
• No wallet private keys are required or read by this script.
• Dry-run is the default. The --live flag must be explicitly passed to execute trades.

> Remixable Template: Fork this skill to add new Kalshi series, adjust

> divergence thresholds, or add position sizing based on gap magnitude.