Current implied probability
Up 98%+52.0pt
Market quality
82 / 100
High quality24h Volume
$71.2K
Liquidity
$25.4K
High liquidityBid / Ask
98.2% / 98.8%
Spread
0.6 pt
Tight spreadComments
0
Market data
Updated 21 minutes ago
Aug 20, 26, 12:00 PMAug 21, 26, 8:00 PM
Trends
Rules
This market will resolve to "Up" if the official S&P 500 Index closing price for S&P 500 (SPX) on Friday, August 21, 2026 is higher than the official S&P 500 Index closing price for SPX on the most recent prior trading day.
- This market will resolve to "Down" if the official S&P 500 Index closing price for S&P 500 (SPX) on Friday, August 21, 2026 is lower than the official S&P 500 Index closing price for SPX on the most recent prior trading day.
- E.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.
- If the two specified closing prices are exactly equal, this market will resolve 50-50.
- Note that all figures will be rounded to the nearest cent using standard rounding.
- If SPX does not trade at all during the regular session, the market will resolve 50-50.
Frequently asked questions
- What are the current odds for S&P 500 (SPX) Up or Down on August 21??
- Polymarket prices Up at 98% as of August 21, 2026.
- When does S&P 500 (SPX) Up or Down on August 21? resolve?
- S&P 500 (SPX) Up or Down on August 21? is scheduled to resolve on August 21, 2026.
- How is S&P 500 (SPX) Up or Down on August 21? settled?
- Polymarket settles this market as follows: This market will resolve to "Up" if the official S&P 500 Index closing price for S&P 500 (SPX) on Friday, August 21, 2026 is higher than the official S&P 500 Index closing price for SPX on the most recent prior trading day.
