This market will resolve to "Up" if the Close price for S&P 500 (SPY) on May 18, 2026 is higher than the Close price for S&P 500 (SPY) on the most recent prior trading day. This market will resolve to "Down" if the Close price for S&P 500 (SPY) on May 18, 2026 is lower than the Close price for S&P 500 (SPY) 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 holiday, in which case it would refer to Thursday, or the next most recent trading day. If the two specified closing prices are exactly equal, this market will resolve 50-50. Closing prices will be used exactly as published by Pyth, without rounding. If S&P 500 (SPY) does not trade at all during the regular session, the market will resolve 50-50. For a standard full trading session, the closing price refers to the Pyth "Close" value of the 1-minute candle corresponding to the final minute of regular trading hours on the primary exchange. If either of the relevant days has no valid Pyth Close value for the 1-minute candle corresponding to the end of regular trading hours on the primary exchange, the market will use the last valid Pyth price achieved during the regular trading hours of the primary exchange as the effective closing price. If no valid Pyth price exists for that trading day due to a system outage, data failure, or other technical disruption, the official closing price published by the primary exchange on which the listed security trades will be used to determine the closing price for that day. Only prices achieved during the regular trading hours of the primary exchange on which the listed security trades (typically 9:30 AM – 4:00 PM ET) will be considered. In the event of a stock split, reverse stock split, or similar corporate action affecting the listed security during the listed time frame, this market will resolve based on split-adjusted prices as displayed on Pyth. The resolution source for this market will be Pyth, specifically the "Close" values for the relevant 1-minute candle available at https://pythdata.app/explore/Equity.US.SPY%2FUSD. Historical 1-minute candles may be accessed by appending a Unix timestamp (seconds) to the Pyth chart URL using the "t=" parameter. Any timestamp within the listed market time frame may be used to view the relevant candle data (e.g., https://pythdata.app/explore/Equity.US.SPY%2FUSD?t=1773432000).