{"source":"polymarket","id":"1058395","ticker":"spx-opens-up-or-down-on-september-22-2026","slug":"spx-opens-up-or-down-on-september-22-2026","title":"S&P 500 (SPX) Opens Up or Down on September 22?","description":"This market will resolve to \"Up\" if the official S&P 500 Index open price for S&P 500 (SPX) on September 22 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 22 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":"2026-09-21T12:01:03Z","end_date":"2026-09-22T20:00:00Z","closed_time":null,"volume":1856.491868,"volume_24hr":1856.491868,"volume_24h_change":null,"normalized_vol_24hr":21.0327205657959,"normalized_volume":12.880706787109375,"liquidity":441.9109,"open_interest":814.34824,"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":0.425,"top_outcome_prob_24h_change":-0.07500000000000001,"top_outcome_volume_24h_change":1856.491868,"updated_at":"2026-09-22T08:17:37.608797Z","fetched_at":"2026-09-22T08:17:37.608797Z","added_at":"2026-09-21T12:10:05.013798Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-september-22-2026","chart_24h":[0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,49.433963,162.123619,591.894436,591.894436,591.894436,671.894436,889.894436,889.894436,900.6087220000001,1268.933278,1268.933278,1268.933278,1326.933278,1344.933278,1344.933278,1346.056868,1346.056868,1463.056868],"kind":"live","markets":[{"source":"polymarket","id":"4788880","event_id":"1058395","slug":"spx-opens-up-or-down-on-september-22-2026","question":"S&P 500 (SPX) Opens Up or Down on September 22?","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 22 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 22 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":[0.425,0.575],"probability":0.425,"spread":0.31,"active":true,"closed":false,"start_date":"2026-09-21T12:01:03Z","end_date":"2026-09-22T20:00:00Z","closed_time":null,"volume":1856.491868,"volume_24hr":1856.491868,"prob_24h_change":-0.07500000000000001,"volume_24h_change":1856.491868,"normalized_vol_24hr":22.527400970458984,"normalized_volume":16.622257232666016,"liquidity":383.8425,"categories":["Finance"],"countries":[],"updated_at":"2026-09-22T08:17:37.937143Z","fetched_at":"2026-09-22T08:17:37.937143Z","added_at":"2026-09-21T12:10:05.155954Z","url":"https://polymarket.com/event/spx-opens-up-or-down-on-september-22-2026/spx-opens-up-or-down-on-september-22-2026","event_title":"S&P 500 (SPX) Opens Up or Down on September 22?","chart_24h":[0.5,0.495,0.615,0.605,0.605,0.625,0.62,0.61,0.625,0.625,0.605,0.505,0.525,0.52,0.515,0.48,0.625,0.62,0.685,0.56,0.55,0.54,0.54,0.755,0.595,0.595,0.68,0.685,0.73,0.73,0.73,0.52]}],"_meta":{"attribution":"pdata.world — aggregated prediction-market data across 8 platforms","canonical_url":"https://pdata.world/events/polymarket/1058395","as_of":"2026-09-22T08:22:19.864335Z","docs":"https://api.pdata.world/docs","cite_as":"According to pdata.world (tracking Polymarket): \"S&P 500 (SPX) Opens Up or Down on September 22?\" — top market at 42% probability across 1 outcome","source_url":null}}