Polymarket$2.32BOIOpen interest: sum of pool liquidity across all active markets, reported by the Polymarket API.
Kalshi$350.67MOIOpen interest: total contracts outstanding across all active markets, reported by the Kalshi API.
Limitless$18.48MOIOpen interest: estimated from total volume traded (USDC). Limitless does not report a separate OI metric.Compare Maine Democratic Senate Primary Winner prediction market odds side by side across Polymarket, Kalshi. Platforms show similar odds, with an average spread of just 1.5pp. Close agreement often signals strong market consensus. With $38.8K in combined trading volume across 7 outcomes, this is one of the notable cross-platform prediction markets.
Graham PlatnerPolymarketKalshiCost: 96¢ per pair → pays $1 at resolution. Gross spread 4.0pp before fees.
View all arbs| Outcome | Polymarket | Kalshi | Spread |
|---|---|---|---|
Graham Platner | 72%-1.0 | 76%±0 | 4.0pp spread |
Janet Mills | 28%+2.5 |
| 1.5pp spread |
Troy Jackson | 0%— | 1%±0 | 0.9pp spread |
Dan Kleban | 0%— | 1%±0 | 0.9pp spread |
Jordan Wood | 0%— | 1%±0 | 0.9pp spread |
Jared Golden | 0%— | 1%±0 | 0.9pp spread |
Chellie Pingree | 0%— | 1%±0 | 0.9pp spread |
