Polymarket$2.36BOIOpen interest: sum of pool liquidity across all active markets, reported by the Polymarket API.
Kalshi$352.10MOIOpen interest: total contracts outstanding across all active markets, reported by the Kalshi API.
Limitless$18.72MOIOpen interest: estimated from total volume traded (USDC). Limitless does not report a separate OI metric.Cross-platform spread detection across Polymarket, Kalshi & Limitless
Cross-platform spread detection across Polymarket, Kalshi & Limitless
When the same event has different prices on Polymarket vs Kalshi, there's a spread. E.g., "Team X wins" at 55% on Polymarket but 60% on Kalshi = 5pp spread.
Buy YES on the cheap platform ($0.55) and NO on the expensive platform ($0.40). Total cost: $0.95. Guaranteed payout: $1.00. Profit: $0.05 per share.
Kalshi charges price-dependent fees (up to 7¢/contract). Polymarket has no explicit fees but has bid/ask spread. Settlement rules may differ. Capital is locked until resolution. USDC/USD peg risk on Polymarket.
Polymarket uses an order book model with no explicit trading fees. Your real cost is the bid/ask spread, which is already reflected in the prices shown. Gas fees on Polygon are negligible (<$0.01).
Fee per contract = min(7¢, ⌈7% × price × (1−price) × 100⌉). Highest at 50/50 prices (~7¢), drops toward 0 at extreme prices. We calculate per-outcome using the actual price, not a flat rate.
Annualized return = net_profit% × (365 / days_to_resolution). Simple annualization, not compound — you can't reinvest in the same arb after it resolves. Uses earliest resolution date between platforms.
| # | Event | Outcome Breakdown | Total Cost | Gap | After Fees | APY | Volume | $100 |
|---|---|---|---|---|---|---|---|---|
| 1 | Who will be the next James Bond actor? 10 outcomes| culture | Callum Turner29¢-23¢ |
| # | Event / Outcome | Direction | Spread | Net Profit | APY | Volume | Trade |
|---|---|---|---|---|---|---|---|
| 1 | Who will be the next James Bond actor? Callum Turner|culture | YES 29¢NO 48¢Cost: 77¢ → pays $1 | 23.0pp | +25.5% |
| # | Event | Top Outcomes | Sum | Gap | After Fees | APY | Volume | Trade |
|---|---|---|---|---|---|---|---|---|
| 1 | Highest grossing movie in 2026? 14 outcomes| culture | The Super Mario Galaxy Movie38% Spider-Man: Brand New Day32% |
| Event | Polymarket | Kalshi | Status | Volume |
|---|---|---|---|---|
Best Actress at the Oscars culture | $0 | $0 | Waiting | $566.2K |
Who will be the next James Bond actor? culture | Active (15) | Active (20) | Live | $105.3K |
Theo James0¢-5¢Tom Holland0¢-3¢| 42.4¢ per $1 payout |
57.6pp |
| +136.1% |
473% 105d |
$105.3K |
| +$136.10 |
| 2 | Big Brother Brasil 26 Winner 20 outcomes| culture | Juliano Floss3¢-1¢Sol Vega0¢-1¢Leandro Rocha0¢-1¢Matheus Moreira0¢-1¢ +16 more | 96.4¢ per $1 payout | 3.6pp | +3.6% | 30% 44d | $29.4K | +$3.63 |
89% 105d |
$105.3K OI: $118.4K |
| 2 | Who will be the next James Bond actor? Jacob Elordi|culture | YES 4¢NO 83¢Cost: 87¢ → pays $1 | 13.2pp | +11.4% | 40% 105d | $105.3K OI: $118.4K |
| 3 | Big Brother Brasil 26 Winner Chaiany Andrade|culture | YES 6¢NO 91¢Cost: 97¢ → pays $1 | 3.5pp | +3.5% | 29% 44d | $29.4K OI: $33.9K |
| 4 | Eurovision Winner 2026 Denmark|culture | YES 11¢NO 87¢Cost: 98¢ → pays $1 | 2.1pp | +1.8% | 11% 60d | $89.9K OI: $188.7K |
| 5 | Who will be the next James Bond actor? Aaron Taylor-Johnson|culture | YES 4¢NO 93¢Cost: 97¢ → pays $1 | 3.5pp | +1.8% | 6% 105d | $105.3K OI: $118.4K |
| 6 | Big Brother Brasil 26 Winner Jonas Sulzbach|culture | YES 11¢NO 85¢Cost: 96¢ → pays $1 | 4.2pp | +1.2% | 10% 44d | $29.4K OI: $33.9K |
| 7 | Big Brother Brasil 26 Winner Milena Moreira|culture | YES 7¢NO 90¢Cost: 97¢ → pays $1 | 3.4pp | +1.1% | 9% 44d | $29.4K OI: $33.9K |
| 8 | Eurovision Winner 2026 Sweden|culture | YES 4¢NO 94¢Cost: 98¢ → pays $1 | 1.6pp | +0.1% | 1% 60d | $89.9K OI: $188.7K |
| 9 | Eurovision Winner 2026 Finland|culture | YES 38¢NO 60¢Cost: 98¢ → pays $1 | 1.7pp | fees > spread | - | $89.9K OI: $188.7K |
| 94.4% |
5.6pp |
| +5.9% |
7% 289d |
$15.7K OI: $488.2K |
| Trade |
Eurovision Winner 2026 culture |
| Active (35) |
| Active (35) |
| Live |
| $89.9K |
Big Brother Brasil 26 Winner culture | Active (23) | Active (22) | Live | $29.4K |
