{"source":"polymarket","id":"725131","ticker":"spx-opens-up-or-down-on-july-21-2026","slug":"spx-opens-up-or-down-on-july-21-2026","title":"S&P 500 (SPX) Opens Up or Down on July 21?","description":"This market will resolve to \"Up\" if the official S&P 500 Index open price for S&P 500 (SPX) on July 21 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 July 21 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":"2026-07-20T12:00:30Z","end_date":"2026-07-21T20:00:00Z","closed_time":null,"volume":18150.901235,"volume_24hr":18150.901235,"volume_24h_change":null,"normalized_vol_24hr":40.2829475402832,"normalized_volume":19.533498764038086,"liquidity":50448.54195,"open_interest":9323.262391,"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":0.9995,"top_outcome_prob_24h_change":0.3395,"top_outcome_volume_24h_change":18421.401235,"updated_at":"2026-07-21T14:23:27.905065Z","fetched_at":"2026-07-21T14:23:27.905065Z","added_at":"2026-07-20T12:10:20.398047Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-july-21-2026","chart_24h":[0.0,1.234563,1.234563,1.234563,1.234563,43.787753,63.787753,103.787753,659.522373,663.689038,703.689038,703.689038,703.689038,1618.689038,1876.6868140000001,1876.6868140000001,1960.7416070000002,1960.7416070000002,1960.7416070000002,2018.4283870000002,2578.8440660000006,2578.8440660000006,2608.8440660000006,2613.8440660000006,2916.8647950000004,3717.2236870000006,3762.1636870000007,5122.689987000001,5438.479447000001,5622.608367000001,6184.787462,6400.487308000001,8699.709308000001,8719.809809,8739.809809,10739.809809,10881.407951000001,12231.649234999999,13099.261235,17940.381235],"markets":[{"source":"polymarket","id":"2999983","event_id":"725131","slug":"spx-opens-up-or-down-on-july-21-2026","question":"S&P 500 (SPX) Opens Up or Down on July 21?","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 July 21 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 July 21 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":[0.9995,0.0005],"probability":0.9995,"spread":0.001,"active":true,"closed":false,"start_date":"2026-07-20T12:00:30Z","end_date":"2026-07-21T20:00:00Z","closed_time":null,"volume":18421.401235,"volume_24hr":18421.401235,"prob_24h_change":0.3395,"volume_24h_change":18421.401235,"normalized_vol_24hr":40.40510177612305,"normalized_volume":26.786334991455078,"liquidity":50448.54195,"categories":["Finance"],"countries":[],"updated_at":"2026-07-21T14:24:55.204746Z","fetched_at":"2026-07-21T14:23:28.122610Z","added_at":"2026-07-20T12:10:20.477962Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-july-21-2026/spx-opens-up-or-down-on-july-21-2026","event_title":"S&P 500 (SPX) Opens Up or Down on July 21?","chart_24h":[0.68,0.585,0.625,0.65,0.675,0.65,0.52,0.54,0.545,0.545,0.47,0.48,0.55,0.545,0.705,0.695,0.725,0.74,0.82,0.845,0.885,0.88,0.88,0.885,0.905,0.945,0.945,0.945,0.945,0.955,0.9775,0.981,0.9865,0.9925,0.992,0.9865,0.992,0.9895,0.9995,0.9995]}],"_meta":{"attribution":"pdata.world — aggregated prediction-market data across 8 platforms","canonical_url":"https://pdata.world/events/polymarket/725131","as_of":"2026-07-21T14:40:39.068575Z","docs":"https://api.pdata.world/docs","cite_as":"According to pdata.world (tracking Polymarket): \"S&P 500 (SPX) Opens Up or Down on July 21?\" — top market at 100% probability across 1 outcome","source_url":null}}