This market will resolve according to the official closing price for S&P 500 (SPX) on the final trading day of December 2026.
If the reported value falls exactly between two brackets, then this market will resolve to the higher range bracket.
If the final trading day of the month is shortened (for example, due to a market-holiday schedule), the official closing price published for that shortened session will still be used for resolution.
If no official closing price is published for that session (for example, due to a trading halt into the close, system issue, delisting, or other disruption), the market will use the last valid on-exchange trade price of the regular session as the effective closing price.
The resolution source for this market is Yahoo Finance, specifically the S&P 500 (SPX) "Close" prices available at https://finance.yahoo.com/quote/%5EGSPC/history, published under "Historical Prices."