{"source":"polymarket","id":"838245","ticker":"spx-opens-up-or-down-on-august-13-2026","slug":"spx-opens-up-or-down-on-august-13-2026","title":"S&P 500 (SPX) Opens Up or Down on August 13?","description":"This market will resolve to \"Up\" if the official S&P 500 Index open price for S&P 500 (SPX) on August 13 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 13 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":"2026-08-12T12:00:19Z","end_date":"2026-08-13T20:00:00Z","closed_time":null,"volume":15521.379895999999,"volume_24hr":15521.379896000002,"volume_24h_change":null,"normalized_vol_24hr":33.02694320678711,"normalized_volume":18.252296447753906,"liquidity":62718.58024,"open_interest":5298.734984,"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":0.396,"top_outcome_volume_24h_change":7715.502731999999,"updated_at":"2026-08-13T13:41:15.666613Z","fetched_at":"2026-08-13T13:41:15.666613Z","added_at":"2026-08-12T12:10:33.793304Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-august-13-2026","chart_24h":[0.0,0.0,0.0,0.0,0.0,50.0,50.0,190.066905,232.405612,232.405612,432.505612,448.359777,448.359777,574.021627,611.511773,739.510864,777.220864,949.8176369999999,957.5757199999998,1089.155931,1469.1359309999998,1673.913943,1783.975379,2421.635593,2621.750347,3170.199091,7715.502731999999],"markets":[{"source":"polymarket","id":"3538303","event_id":"838245","slug":"spx-opens-up-or-down-on-august-13-2026","question":"S&P 500 (SPX) Opens Up or Down on August 13?","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 13 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 13 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":"2026-08-12T12:00:19Z","end_date":"2026-08-13T20:00:00Z","closed_time":null,"volume":15521.379895999999,"volume_24hr":15521.379896000002,"prob_24h_change":0.396,"volume_24h_change":7715.502731999999,"normalized_vol_24hr":33.671749114990234,"normalized_volume":23.507293701171875,"liquidity":62718.58024,"categories":["Finance"],"countries":[],"updated_at":"2026-08-13T13:41:15.881889Z","fetched_at":"2026-08-13T13:41:15.881889Z","added_at":"2026-08-12T12:10:33.966608Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-august-13-2026/spx-opens-up-or-down-on-august-13-2026","event_title":"S&P 500 (SPX) Opens Up or Down on August 13?","chart_24h":[0.595,0.565,0.57,0.555,0.56,0.565,0.565,0.485,0.54,0.52,0.53,0.535,0.495,0.525,0.545,0.585,0.595,0.64,0.685,0.605,0.675,0.75,0.76,0.805,0.845,0.86,0.986]}],"_meta":{"attribution":"pdata.world — aggregated prediction-market data across 8 platforms","canonical_url":"https://pdata.world/events/polymarket/838245","as_of":"2026-08-13T13:43:27.241994Z","docs":"https://api.pdata.world/docs","cite_as":"According to pdata.world (tracking Polymarket): \"S&P 500 (SPX) Opens Up or Down on August 13?\" — top market at 100% probability across 1 outcome","source_url":null}}