S&P 500 (SPX) Up or Down on September 21?

This market will resolve to "Up" if the official S&P 500 Index closing price for S&P 500 (SPX) on Monday, September 21, 2026 is higher than the official S&P 500 Index closing price for SPX on the most recent prior trading day. This market will resolve to "Down" if the official S&P 500 Index closing price for S&P 500 (SPX) on Monday, September 21, 2026 is lower than the official S&P 500 Index closing price for SPX on the most recent prior trading day. E.g., ordinarily, a market on Monday would refer to the previous Friday for its most recent closing price, unless that Friday were a market ho…