Cross-Market Arbitrage Feed
Find probability discrepancies between Polymarket, Metaculus, and other prediction platforms
Automated cross-platform market comparison using fuzzy matching to identify same-event markets across Polymarket and Metaculus. Surfaces probability spreads that represent potential arbitrage opportunities or informational asymmetries between platforms.
How customers use this
Pure cross-platform arbitrage
Buy YES at 45% on Polymarket and sell the equivalent at 55% on Kalshi for a risk-free 10% spread. This data surfaces those opportunities in real time across prediction market platforms.
Probability calibration
If Polymarket says 60% but the Metaculus community says 40%, one market is wrong. Compare probabilities across platforms to find the mispriced side and trade against it.
Informed liquidity provision
Provide liquidity on the side that's cheaper relative to other platforms. When you know the cross-market fair value, you can confidently post orders knowing the spread is in your favor.
Sample data
Example responses from the API. Each query returns structured JSON.
GET /api/v1/pm/arb/opportunities?min_spread=0.05
{
"opportunities": [
{ "question": "Will Fed cut rates in Jan 2026?", "polymarket_yes": 0.42, "kalshi_yes": 0.54, "spread": 0.12, "combined_liquidity_usd": 892000 }
],
"total_opportunities": 23,
"updated_at": "2025-12-01T14:30:00Z"
}GET /api/v1/pm/arb/abc123
{
"arb_id": "abc123",
"question": "Will Fed cut rates in Jan 2026?",
"platforms": {
"polymarket": { "yes_price": 0.42, "volume_24h": 341000 },
"kalshi": { "yes_price": 0.54, "volume_24h": 189000 }
},
"spread": 0.12,
"spread_direction": "buy_polymarket_sell_kalshi"
}GET /api/v1/pm/arb/stats
{
"markets_tracked": 4821,
"active_arb_opportunities": 23,
"avg_spread": 0.034,
"platforms_compared": ["polymarket", "kalshi", "metaculus"],
"last_updated": "2025-12-01T14:30:00Z"
}Use cases
- ✓ Identify cross-platform arbitrage opportunities
- ✓ Compare probability estimates across prediction platforms
- ✓ Detect informational advantages between markets
- ✓ Build cross-market trading strategies
- ✓ Research prediction market efficiency
Response fields
| Field | Type | Description |
|---|---|---|
| polymarket_id | string | Polymarket market/condition ID |
| polymarket_question | string | Polymarket market question text |
| polymarket_prob | number | Polymarket probability (0-1) |
| comparison_platform | string | Name of comparison platform |
| comparison_prob | number | Comparison platform probability |
| spread | number | Probability spread (Polymarket - comparison) |
| abs_spread | number | Absolute probability spread |
Example queries
Find arbitrage opportunities
GET /api/v1/pm/arb/opportunities?min_spread=0.05Markets with 5%+ probability spread across platforms
Cross-platform comparison
GET /api/v1/pm/arb/0x1234All platform comparisons for a specific Polymarket market
Free dataset stats
GET /api/v1/pm/arb/statsReturns coverage and spread statistics