S&P 500 (SPX) Opens Up or Down on April 28?

This market will resolve to "Up" if the official S&P 500 Index open price for S&P 500 (SPX) on April 28 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 open price for S&P 500 (SPX) on April 28 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