{"_meta":{"attribution":"Data aggregated by pdata.world (https://pdata.world) from 8 prediction-market venues; CC BY 4.0; source data © each venue.","canonical_url":"https://pdata.world/events/polymarket/1265587","as_of":"2026-10-28T17:44:54.997356Z","docs":"https://api.pdata.world/docs","cite_as":"According to pdata.world (tracking Polymarket): \"S&P 500 (SPX) Opens Up or Down on October 28?\" — 100% as of 2026-10-28 UTC. https://pdata.world/events/polymarket/1265587","source_url":"https://polymarket.com/event/spx-opens-up-or-down-on-october-28-2026"},"source":"polymarket","id":"1265587","ticker":"spx-opens-up-or-down-on-october-28-2026","slug":"spx-opens-up-or-down-on-october-28-2026","title":"S&P 500 (SPX) Opens Up or Down on October 28?","description":"This market will resolve to \"Up\" if the official S&P 500 Index open price for S&P 500 (SPX) on October 28 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 28 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":"2026-10-27T12:00:58Z","end_date":"2026-10-28T20:00:00Z","closed_time":null,"volume":5671.144986,"volume_24hr":5671.144986000002,"volume_24h_change":null,"normalized_vol_24hr":26.89978790283203,"normalized_volume":16.965137481689453,"liquidity":17835.78311,"open_interest":3760.592683,"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":0.49950000000000006,"top_outcome_volume_24h_change":5671.144986000002,"updated_at":"2026-10-28T17:26:23.718174Z","fetched_at":"2026-10-28T17:26:23.718174Z","added_at":"2026-10-27T12:19:58.145878Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-october-28-2026","chart_24h":[0.0,0.0,0.0,0.0,0.0,0.0,40.0,40.0,40.0,60.0,60.0,107.54193000000001,107.54193000000001,194.41239099999999,351.41239099999996,578.1923909999999,673.5331909999999,678.543191,963.00473,1073.8226300000001,1418.797261,1965.153586,5528.534986,5664.894986000002,5664.894986000001,5671.144986000001,5671.144986000002],"kind":"live","mutually_exclusive":false,"markets_total":1,"markets":[{"source":"polymarket","id":"6296803","event_id":"1265587","slug":"spx-opens-up-or-down-on-october-28-2026","question":"S&P 500 (SPX) Opens Up or Down on October 28?","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 28 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 28 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":"2026-10-27T12:00:58Z","end_date":"2026-10-28T20:00:00Z","closed_time":null,"result":null,"volume":5671.144986000001,"volume_24hr":5671.144986000002,"prob_24h_change":0.49950000000000006,"volume_24h_change":5671.144986000002,"normalized_vol_24hr":28.71282958984375,"normalized_volume":21.918439865112305,"liquidity":17835.78311,"categories":["Finance"],"countries":[],"updated_at":"2026-10-28T17:26:24.515236Z","fetched_at":"2026-10-28T17:26:24.515236Z","added_at":"2026-10-27T12:19:58.256374Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-october-28-2026/spx-opens-up-or-down-on-october-28-2026","event_title":"S&P 500 (SPX) Opens Up or Down on October 28?","chart_24h":[0.5,0.435,0.53,0.55,0.56,0.425,0.54,0.475,0.55,0.575,0.555,0.535,0.52,0.575,0.59,0.755,0.79,0.69,0.77,0.735,0.93,0.9755,0.9995,0.9995,0.9995,0.9995,0.9995]}]}