{"source":"polymarket","id":"870363","ticker":"spx-opens-up-or-down-on-august-19-2026","slug":"spx-opens-up-or-down-on-august-19-2026","title":"S&P 500 (SPX) Opens Up or Down on August 19?","description":"This market will resolve to \"Up\" if the official S&P 500 Index open price for S&P 500 (SPX) on August 19 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 August 19 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":"2026-08-18T12:00:12Z","end_date":"2026-08-19T20:00:00Z","closed_time":null,"volume":3868.217006,"volume_24hr":3868.2170060000003,"volume_24h_change":null,"normalized_vol_24hr":29.115299224853516,"normalized_volume":15.53888988494873,"liquidity":167.6848,"open_interest":2808.317854,"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":0.595,"top_outcome_prob_24h_change":0.09499999999999997,"top_outcome_volume_24h_change":3868.2170060000003,"updated_at":"2026-08-19T10:33:25.657307Z","fetched_at":"2026-08-19T10:33:25.657307Z","added_at":"2026-08-18T12:25:35.081151Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-august-19-2026","chart_24h":[0.0,0.0,2.24,2.24,7.24,7.24,7.24,101.11999999999999,141.11999999999998,141.11999999999998,1494.257033,1632.407975,1898.245431,1928.245431,2274.407387,2312.648765,2569.538592,2830.313508,3509.1205440000003,3800.8140220000005,3858.2170060000008,3868.2170060000003],"markets":[{"source":"polymarket","id":"3695167","event_id":"870363","slug":"spx-opens-up-or-down-on-august-19-2026","question":"S&P 500 (SPX) Opens Up or Down on August 19?","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 August 19 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 August 19 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":[0.595,0.405],"probability":0.595,"spread":0.09,"active":true,"closed":false,"start_date":"2026-08-18T12:00:12Z","end_date":"2026-08-19T20:00:00Z","closed_time":null,"volume":3868.217006,"volume_24hr":3868.2170060000003,"prob_24h_change":0.09499999999999997,"volume_24h_change":3868.2170060000003,"normalized_vol_24hr":30.07438850402832,"normalized_volume":20.021343231201172,"liquidity":167.6848,"categories":["Finance"],"countries":[],"updated_at":"2026-08-19T10:33:25.869204Z","fetched_at":"2026-08-19T10:33:25.869204Z","added_at":"2026-08-18T12:25:35.206815Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-august-19-2026/spx-opens-up-or-down-on-august-19-2026","event_title":"S&P 500 (SPX) Opens Up or Down on August 19?","chart_24h":[0.5,0.535,0.535,0.535,0.515,0.51,0.495,0.52,0.5,0.58,0.54,0.47,0.55,0.39,0.33,0.525,0.585,0.69,0.635,0.595]}],"_meta":{"attribution":"pdata.world — aggregated prediction-market data across 8 platforms","canonical_url":"https://pdata.world/events/polymarket/870363","as_of":"2026-08-19T10:45:17.985087Z","docs":"https://api.pdata.world/docs","cite_as":"According to pdata.world (tracking Polymarket): \"S&P 500 (SPX) Opens Up or Down on August 19?\" — top market at 60% probability across 1 outcome","source_url":null}}