{"source":"polymarket","id":"987975","ticker":"spx-opens-up-or-down-on-september-9-2026","slug":"spx-opens-up-or-down-on-september-9-2026","title":"S&P 500 (SPX) Opens Up or Down on September 9?","description":"This market will resolve to \"Up\" if the official S&P 500 Index open price for S&P 500 (SPX) on September 9 is higher than the official S&P 500 Index closing price for SPX on the most recent prior trading day.\n\nThis market will resolve to \"Down\" if the official S&P 500 Index open price for S&P 500 (SPX) on September 9 is lower than the official S&P 500 Index closing price for SPX on the most recent prior trading day.\n\nE.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.\n\nIf the two prices are exactly equal, this market will resolve 50-50. Note that all figures will be rounded to the nearest cent using standard rounding.\n\nIf SPX does not trade at all during the regular session, the market will resolve 50-50.\n\nIf either of the relevant days are shortened (for example, due to a market holiday schedule), the official open/close price published by S&P 500 Index for that shortened session will still be used for resolution.\n\nIf the previous trading day has 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.\n\nThe resolution source for this market is the Wall Street Journal, specifically the Open/Close values published by the WSJ under \"Historical Prices\".\n\nUS: https://www.wsj.com/market-data/stocks\nEMEA: https://www.wsj.com/market-data/stocks/emea\nASIA: https://www.wsj.com/market-data/stocks/asia","image":"https://polymarket-upload.s3.us-east-2.amazonaws.com/s-and-p-500-1e40af6979.png","icon":"https://polymarket-upload.s3.us-east-2.amazonaws.com/s-and-p-500-1e40af6979.png","active":true,"closed":false,"start_date":"2026-09-08T12:01:00Z","end_date":"2026-09-09T20:00:00Z","closed_time":null,"volume":2248.6188389999998,"volume_24hr":2248.618839,"volume_24h_change":null,"normalized_vol_24hr":24.03522491455078,"normalized_volume":13.554018020629883,"liquidity":472.5351,"open_interest":4090.159753,"categories":["Finance"],"tags":[{"id":"102683","slug":"spx","label":"SPX"},{"id":"102127","slug":"up-or-down","label":"Up or Down"},{"id":"102281","slug":"daily","label":"Daily"},{"id":"102682","slug":"indicies","label":"Indicies"},{"id":"120","slug":"finance","label":"Finance"},{"id":"102169","slug":"hide-from-new","label":"Hide From New"}],"synthetic":false,"is_group":false,"group_key":null,"parent_event_id":null,"probability":null,"spread":null,"top_outcome":"","top_outcome_probability":0.505,"top_outcome_prob_24h_change":0.0050000000000000044,"top_outcome_volume_24h_change":2248.618839,"updated_at":"2026-09-09T08:53:37.356527Z","fetched_at":"2026-09-09T08:53:37.356527Z","added_at":"2026-09-08T12:12:44.818305Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-september-9-2026","chart_24h":[0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,12.0,122.0,122.0,242.0,373.28,394.28,399.28,774.440164,794.4401640000001,959.440164,1046.440164,1503.500164,1723.500164,1946.200164,2019.200164,2127.20093,2225.2009299999995],"kind":"live","markets":[{"source":"polymarket","id":"4362263","event_id":"987975","slug":"spx-opens-up-or-down-on-september-9-2026","question":"S&P 500 (SPX) Opens Up or Down on September 9?","group_item_title":null,"description":"This market will resolve to \"Up\" if the official S&P 500 Index open price for S&P 500 (SPX) on September 9 is higher than the official S&P 500 Index closing price for SPX on the most recent prior trading day.\n\nThis market will resolve to \"Down\" if the official S&P 500 Index open price for S&P 500 (SPX) on September 9 is lower than the official S&P 500 Index closing price for SPX on the most recent prior trading day.\n\nE.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.\n\nIf the two prices are exactly equal, this market will resolve 50-50. Note that all figures will be rounded to the nearest cent using standard rounding.\n\nIf SPX does not trade at all during the regular session, the market will resolve 50-50.\n\nIf either of the relevant days are shortened (for example, due to a market holiday schedule), the official open/close price published by S&P 500 Index for that shortened session will still be used for resolution.\n\nIf the previous trading day has 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.\n\nThe resolution source for this market is the Wall Street Journal, specifically the Open/Close values published by the WSJ under \"Historical Prices\".\n\nUS: https://www.wsj.com/market-data/stocks\nEMEA: https://www.wsj.com/market-data/stocks/emea\nASIA: https://www.wsj.com/market-data/stocks/asia","image":"https://polymarket-upload.s3.us-east-2.amazonaws.com/s-and-p-500-1e40af6979.png","icon":"https://polymarket-upload.s3.us-east-2.amazonaws.com/s-and-p-500-1e40af6979.png","outcomes":["Up","Down"],"outcome_prices":[0.505,0.495],"probability":0.505,"spread":0.07,"active":true,"closed":false,"start_date":"2026-09-08T12:01:00Z","end_date":"2026-09-09T20:00:00Z","closed_time":null,"volume":2248.6188389999998,"volume_24hr":2248.618839,"prob_24h_change":0.0050000000000000044,"volume_24h_change":2248.618839,"normalized_vol_24hr":24.06081199645996,"normalized_volume":17.47896957397461,"liquidity":892.9869,"categories":["Finance"],"countries":[],"updated_at":"2026-09-09T08:53:37.682007Z","fetched_at":"2026-09-09T08:53:37.682007Z","added_at":"2026-09-08T12:12:44.951480Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-september-9-2026/spx-opens-up-or-down-on-september-9-2026","event_title":"S&P 500 (SPX) Opens Up or Down on September 9?","chart_24h":[0.5,0.615,0.625,0.605,0.605,0.615,0.715,0.705,0.685,0.61,0.64,0.63,0.395,0.475,0.475,0.46,0.475,0.405,0.45,0.515,0.575,0.59,0.565,0.575,0.57,0.625,0.64,0.68,0.68,0.61,0.635]}],"_meta":{"attribution":"pdata.world — aggregated prediction-market data across 8 platforms","canonical_url":"https://pdata.world/events/polymarket/987975","as_of":"2026-09-09T08:59:57.890766Z","docs":"https://api.pdata.world/docs","cite_as":"According to pdata.world (tracking Polymarket): \"S&P 500 (SPX) Opens Up or Down on September 9?\" — top market at 50% probability across 1 outcome","source_url":null}}