{"source":"polymarket","id":"1108316","ticker":"spx-opens-up-or-down-on-october-1-2026","slug":"spx-opens-up-or-down-on-october-1-2026","title":"S&P 500 (SPX) Opens Up or Down on October 1?","description":"This market will resolve to \"Up\" if the official S&P 500 Index open price for S&P 500 (SPX) on October 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 October 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":"2026-09-30T12:00:58Z","end_date":"2026-10-01T20:00:00Z","closed_time":null,"volume":3473.988324000006,"volume_24hr":3473.988324,"volume_24h_change":null,"normalized_vol_24hr":29.3358211517334,"normalized_volume":15.109750747680664,"liquidity":819.0687,"open_interest":2158.841085,"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":0.805,"top_outcome_prob_24h_change":0.19000000000000006,"top_outcome_volume_24h_change":3473.988324,"updated_at":"2026-10-01T11:30:13.205242Z","fetched_at":"2026-10-01T11:30:13.205242Z","added_at":"2026-09-30T12:19:45.041707Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-october-1-2026","chart_24h":[0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,285.222223,491.697543,491.697543,531.697543,531.697543,531.697543,531.697543,531.697543,670.697543,691.860328,724.860328,752.360328,780.931758,885.931758,902.931758,1892.454916,2271.2650639999997,2738.245064,2982.9130669999986,3092.913066999999,3092.9130669999995],"kind":"live","markets":[{"source":"polymarket","id":"5153630","event_id":"1108316","slug":"spx-opens-up-or-down-on-october-1-2026","question":"S&P 500 (SPX) Opens Up or Down on October 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 October 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 October 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":[0.805,0.195],"probability":0.805,"spread":0.11,"active":true,"closed":false,"start_date":"2026-09-30T12:00:58Z","end_date":"2026-10-01T20:00:00Z","closed_time":null,"volume":3473.988324000006,"volume_24hr":3473.988324,"prob_24h_change":0.19000000000000006,"volume_24h_change":3473.988324,"normalized_vol_24hr":29.929462432861328,"normalized_volume":19.503833770751953,"liquidity":839.1988,"categories":["Finance"],"countries":[],"updated_at":"2026-10-01T11:30:13.368080Z","fetched_at":"2026-10-01T11:30:13.368080Z","added_at":"2026-09-30T12:19:45.170991Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-october-1-2026/spx-opens-up-or-down-on-october-1-2026","event_title":"S&P 500 (SPX) Opens Up or Down on October 1?","chart_24h":[0.615,0.615,0.625,0.625,0.605,0.625,0.615,0.51,0.53,0.57,0.58,0.525,0.565,0.82,0.715,0.72,0.825,0.935,0.94,0.945,0.91,0.595,0.585,0.71,0.835,0.835,0.92]}],"_meta":{"attribution":"pdata.world — aggregated prediction-market data across 8 platforms","canonical_url":"https://pdata.world/events/polymarket/1108316","as_of":"2026-10-01T11:33:50.856068Z","docs":"https://api.pdata.world/docs","cite_as":"According to pdata.world (tracking Polymarket): \"S&P 500 (SPX) Opens Up or Down on October 1?\" — top market at 80% probability across 1 outcome","source_url":null}}