TOTAL VOLUME:
$54.2b
24H VOL:
$217,900,088
OPEN INTEREST:
$1,256,149,940
499,530
Markets across
13,705
events
MATCHED EVENTS:
1,785
PLATFORM COVERAGE:
4
Polymarket:
51%
VS.
Kalshi:
49%
S&P 500 (SPX) Up or Down on March 26?
Description
This market will resolve to "Up" if the official S&P 500 Index closing price for S&P 500 (SPX) on Thursday, March 26, 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 26, 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 resolves on directional price movement (Up/Down vs. prior trading day close), while Kalshi resolves on absolute index level thresholds (50 different price points). These are fundamentally different settlement mechanisms that will produce divergent outcomes for the same underlying event.Hero Tip:
If you trade this market, understand that Polymarket bets on direction relative to March 25 close, while Kalshi bets on whether SPX ends above specific absolute levels. A market that is 'Up' on Polymarket (higher than March 25) could resolve YES or NO on Kalshi depending on which of the 50 thresholds apply. Arbitrage risk is extreme: the same March 26 closing price will settle differently on each platform.Critical Divergence Points:
- Polymarket: Distinct stance: Resolves based on directional comparison—YES if March 26 SPX close is higher than the most recent prior trading day close (typically March 25), NO if lower, 50-50 if equal. Source is Wall Street Journal Historical Prices Close values. Quote: 'This market will resolve to Up if the official S&P 500 Index closing price for S&P 500 (SPX) on Thursday, March 26, 2026 is higher than the official S&P 500 Index closing price for SPX on the most recent prior trading day.'
- Kalshi: Distinct stance: Resolves YES if end-of-day SPX on March 26, 2026 is above any of 50 different absolute price thresholds (ranging from 5799.9999 to 7274.9999). No directional comparison; no reference to prior close. All 50 conditions resolve to YES independently. Quote: 'If the end-of-day S&P 500 index value on March 26, 2026 is above 6524.9999, then the market resolves to Yes.'
Follow the signals, not the noise
Get insights on market conviction, notable shifts, and what the data is quietly signaling.