{"source":"polymarket","id":"964002","ticker":"spx-opens-up-or-down-on-september-8-2026","slug":"spx-opens-up-or-down-on-september-8-2026","title":"S&P 500 (SPX) Opens Up or Down on September 8?","description":"This market will resolve to \"Up\" if the official S&P 500 Index open price for S&P 500 (SPX) on September 8 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 September 8 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":"2026-09-04T12:01:01Z","end_date":"2026-09-08T20:00:00Z","closed_time":null,"volume":3529.332367,"volume_24hr":2181.6857059999998,"volume_24h_change":null,"normalized_vol_24hr":25.39817237854004,"normalized_volume":15.183235168457031,"liquidity":1279.7656,"open_interest":1902.047756,"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":0.14,"top_outcome_prob_24h_change":-0.175,"top_outcome_volume_24h_change":3224.63101,"updated_at":"2026-09-08T11:09:57.674375Z","fetched_at":"2026-09-08T11:09:57.674375Z","added_at":"2026-09-04T12:13:41.176459Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-september-8-2026","chart_24h":[150.406236,200.40623600000004,234.25238700000003,241.72238700000003,258.722387,258.722387,304.722387,304.722387,304.722387,304.722387,324.722387,324.722387,324.722387,342.534887,342.534887,342.534887,342.534887,342.534887,352.534887,414.734887,404.734887,404.734887,424.734887,496.558417,528.748417,696.0046550000001,1371.5134819999998,1484.823482,2210.473482,2210.473482,2181.6857059999998],"kind":"live","markets":[{"source":"polymarket","id":"4212394","event_id":"964002","slug":"spx-opens-up-or-down-on-september-8-2026","question":"S&P 500 (SPX) Opens Up or Down on September 8?","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 September 8 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 September 8 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":[0.14,0.86],"probability":0.14,"spread":0.1,"active":true,"closed":false,"start_date":"2026-09-04T12:01:01Z","end_date":"2026-09-08T20:00:00Z","closed_time":null,"volume":3529.332367,"volume_24hr":3375.037246,"prob_24h_change":-0.175,"volume_24h_change":3224.63101,"normalized_vol_24hr":29.11740493774414,"normalized_volume":19.57950210571289,"liquidity":1270.2953,"categories":["Finance"],"countries":[],"updated_at":"2026-09-08T11:09:58.003744Z","fetched_at":"2026-09-08T11:09:58.003744Z","added_at":"2026-09-04T12:13:41.275640Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-september-8-2026/spx-opens-up-or-down-on-september-8-2026","event_title":"S&P 500 (SPX) Opens Up or Down on September 8?","chart_24h":[0.315,0.23,0.35,0.29,0.315,0.37,0.38,0.34,0.385,0.375,0.37,0.37,0.4,0.295,0.245,0.285,0.28,0.45,0.45,0.51,0.515,0.33,0.1,0.2,0.145,0.13,0.07,0.17,0.305,0.14]}],"_meta":{"attribution":"pdata.world — aggregated prediction-market data across 8 platforms","canonical_url":"https://pdata.world/events/polymarket/964002","as_of":"2026-09-08T11:22:33.943840Z","docs":"https://api.pdata.world/docs","cite_as":"According to pdata.world (tracking Polymarket): \"S&P 500 (SPX) Opens Up or Down on September 8?\" — top market at 14% probability across 1 outcome","source_url":null}}