S&P 500 (SPX) Up or Down on August 31? Odds & Prediction Markets

Name: S&P 500 (SPX) Up or Down on August 31?
Start: 2026-08-28T12:00:56.000Z
End: 2026-08-31T20:00:00.000Z

Description

This market will resolve to "Up" if the official S&P 500 Index closing price for S&P 500 (SPX) on Monday, August 31, 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, August 31, 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 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. Note that all figures will be rounded to the nearest cent using standard rounding. If SPX does not trade at all during the regular session, the market will resolve 50-50. If either of the relevant days are shortened (for example, due to a market holiday schedule), the official closing price published by S&P 500 Index for that shortened session will still be used for resolution. If either of the relevant days have no official closing price (for example, due to a trading halt into the market 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 the Wall Street Journal, specifically the Close values published by the WSJ under "Historical Prices". US: https://www.wsj.com/market-data/stocks EMEA: https://www.wsj.com/market-data/stocks/emea ASIA: https://www.wsj.com/market-data/stocks/asia

Polymarket

This market will resolve to "Up" if the official S&P 500 Index closing price for S&P 500 (SPX) on Monday, August 31, 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, August 31, 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 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. Note that all figures will be rounded to the nearest cent using standard rounding. If SPX does not trade at all during the regular session, the market will resolve 50-50. If either of the relevant days are shortened (for example, due to a market holiday schedule), the official closing price published by S&P 500 Index for that shortened session will still be used for resolution. If either of the relevant days have no official closing price (for example, due to a trading halt into the market 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 the Wall Street Journal, specifically the Close values published by the WSJ under "Historical Prices". US: https://www.wsj.com/market-data/stocks EMEA: https://www.wsj.com/market-data/stocks/emea ASIA: https://www.wsj.com/market-data/stocks/asia

Frequently asked questions

On Polymarket, the dashboard for the S&P 500 direction market tracks real-time odds, price history, and 24-hour volume of $93,304. It shows how traders on Polymarket are positioning around the likelihood of the S&P 500 moving higher or lower by the close on Aug 31, 2026. The interface updates continuously, reflecting the latest betting activity and market sentiment for this specific prediction.

This market resolves around Aug 31, 2026, with the outcome confirmed once the event is verifiable from credible public reporting. By that date, the final closing value of the S&P 500 will be compared to its price at the market’s defined reference point, determining whether the index moves up or down for settlement.

Key events that could shift this market include major U.S. economic reports — such as nonfarm payrolls, inflation data, and Federal Reserve policy decisions — as well as significant earnings seasons for large-cap companies. Geopolitical developments, sudden market corrections, or surprise policy moves may also cause rapid adjustments in trader sentiment and shift odds before Aug 31, 2026.

S&P 500 (SPX) Up or Down on August 31?

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