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 Which party will win the U.S. Senate in 2026? prediction market odds side by side across Polymarket, Kalshi. Platforms show similar odds, with an average spread of just 1.0pp. Close agreement often signals strong market consensus. With $61.7K in combined trading volume across 2 outcomes, this is one of the notable cross-platform prediction markets.
| Outcome | Polymarket | Kalshi | Spread |
|---|---|---|---|
 Democratic Party | 51%— | 50%±0 | 0.5pp spread |
 Republican Party | 50% |
51%+1.0 |
| 1.5pp spread |
