Polymarket$2.87BOIOpen interest: sum of pool liquidity across all active markets, reported by the Polymarket API.
Kalshi$354.88MOIOpen interest: total contracts outstanding across all active markets, reported by the Kalshi API.
Limitless$23.03MOIOpen interest: estimated from total volume traded (USDC). Limitless does not report a separate OI metric.
Updated Today
As of March 18, 2026, the Polymarket odds for What will S&P 500 (SPX) close at end of 2026? are: <$6,000: 30%, $6,000-$6,500: 25%, $6,500-$7,000: 19%, $7,000-$7,500: 18%, >$8,000: 18%. These probabilities are derived from real-money trading and update in real time.
What will S&P 500 (SPX) close at end of 2026? is currently available on Polymarket. Check PredictMarketCap for cross-platform availability as new markets are added regularly.
Prediction market odds reflect the aggregate opinion of traders who risk real money on outcomes. The price of a share (e.g., 65¢) represents the market's implied probability (65%). Prices move as traders buy and sell based on new information, polls, and analysis.
