{"source":"polymarket","id":"941363","ticker":"spx-opens-up-or-down-on-september-1-2026","slug":"spx-opens-up-or-down-on-september-1-2026","title":"S&P 500 (SPX) Opens Up or Down on September 1?","description":"This market will resolve to \"Up\" if the official S&P 500 Index open price for S&P 500 (SPX) on September 1 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 1 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":"2026-08-31T12:01:02Z","end_date":"2026-09-01T20:00:00Z","closed_time":null,"volume":1978.285126,"volume_24hr":1978.2851259999998,"volume_24h_change":null,"normalized_vol_24hr":21.747058868408203,"normalized_volume":13.113410949707031,"liquidity":1660.547,"open_interest":1278.139746,"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":0.055,"top_outcome_prob_24h_change":-0.44,"top_outcome_volume_24h_change":1978.285126,"updated_at":"2026-09-01T09:08:50.568618Z","fetched_at":"2026-09-01T09:08:50.568618Z","added_at":"2026-08-31T12:02:13.775955Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-september-1-2026","chart_24h":[0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,187.27,244.804244,433.473865,451.655682,571.655682,576.825172,576.825172,576.825172,815.304221,845.304221,877.265004,992.506271,992.506271,1002.506271,1280.6406099999997,1280.6406099999997,1280.6406099999997,1315.6896329999997,1361.6896329999997,1513.0296329999999],"kind":"live","markets":[{"source":"polymarket","id":"4024700","event_id":"941363","slug":"spx-opens-up-or-down-on-september-1-2026","question":"S&P 500 (SPX) Opens Up or Down on September 1?","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 1 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 1 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":[0.055,0.945],"probability":0.055,"spread":0.07,"active":true,"closed":false,"start_date":"2026-08-31T12:01:02Z","end_date":"2026-09-01T20:00:00Z","closed_time":null,"volume":1978.285126,"volume_24hr":1978.2851259999998,"prob_24h_change":-0.44,"volume_24h_change":1978.285126,"normalized_vol_24hr":21.915449142456055,"normalized_volume":16.903940200805664,"liquidity":1660.6293,"categories":["Finance"],"countries":[],"updated_at":"2026-09-01T09:08:50.767091Z","fetched_at":"2026-09-01T09:08:50.767091Z","added_at":"2026-08-31T12:02:13.945410Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-september-1-2026/spx-opens-up-or-down-on-september-1-2026","event_title":"S&P 500 (SPX) Opens Up or Down on September 1?","chart_24h":[0.5,0.625,0.615,0.625,0.625,0.615,0.615,0.625,0.625,0.62,0.605,0.615,0.61,0.535,0.625,0.53,0.585,0.565,0.575,0.54,0.545,0.545,0.5,0.51,0.56,0.515,0.505,0.625,0.63,0.62,0.725,0.605,0.105]}],"_meta":{"attribution":"pdata.world — aggregated prediction-market data across 8 platforms","canonical_url":"https://pdata.world/events/polymarket/941363","as_of":"2026-09-01T09:09:14.019353Z","docs":"https://api.pdata.world/docs","cite_as":"According to pdata.world (tracking Polymarket): \"S&P 500 (SPX) Opens Up or Down on September 1?\" — top market at 6% probability across 1 outcome","source_url":null}}