TOTAL VOLUME:
$61.9b
24H VOL:
$249,705,498
24H TRANSACTIONS:
600,069,390
OPEN INTEREST:
$1,354,509,605
579,516
Markets across
14,317
events
MATCHED EVENTS:
4,116
PLATFORM COVERAGE:
4
Polymarket:
50%
VS.
Kalshi:
50%
S&P 500 (SPX) Up or Down on March 19? Odds & Prediction Markets
Closed: Mar 19, 7:00 PM EST
Kalshi
Description
This market will resolve to "Up" if the official S&P 500 Index closing price for S&P 500 (SPX) on Thursday, March 19, 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 Thursday, March 19, 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. If either of the relevant days are shortened (for example, due to a market holiday schedule), the official closing price published by S&P 500 Index for that shortened session will still be used for resolution. If either of the relevant days have 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. The resolution source for this market is the Wall Street Journal, specifically the Close values published by the WSJ under "Historical Prices". US: https://www.wsj.com/market-data/stocks EMEA: https://www.wsj.com/market-data/stocks/emea ASIA: https://www.wsj.com/market-data/stocks/asia
PredictionHero - Resolution Divergence Alerts (RDA)
Divergence Detected
Issue:
Polymarket and Kalshi use fundamentally incompatible resolution frameworks. Polymarket resolves based on directional price movement (Up/Down relative to prior trading day), while Kalshi contains 60 separate binary markets each resolving on absolute SPX index thresholds. These are logically distinct events with no common resolution path.Hero Tip:
Do not assume these markets are equivalent. On Polymarket, you are betting on directional movement only (e.g., SPX closes higher than March 18). On Kalshi, you are betting on 60 separate absolute price levels. A single SPX close on March 19 will resolve differently across the two platforms. Example: if SPX closes at 6500 on March 19 and was 6400 on March 18, Polymarket resolves YES (Up), but Kalshi resolves YES on only those thresholds below 6500 and NO on those above.Critical Divergence Points:
Polymarket:
Outlier: Resolves as a single binary event based on directional price movement. YES if March 19 SPX close is higher than the most recent prior trading day close; NO if lower; 50-50 if equal. Source: Wall Street Journal Historical Prices Close values. Key quote: 'This market will resolve to Up if the official S&P 500 Index closing price for S&P 500 (SPX) on Thursday, March 19, 2026 is higher than the official S&P 500 Index closing price for SPX on the most recent prior trading day.'Kalshi:
Outlier: Resolves as 60 separate binary markets, each tied to a distinct absolute SPX index threshold (ranging from 5949.9999 to 7424.9999). Each market independently resolves YES if end-of-day SPX on March 19 exceeds its specific threshold, NO otherwise. No directional comparison to prior day. Key quote: 'If the end-of-day S&P 500 index value on March 19, 2026 is above [threshold], then the market resolves to Yes.'
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