TOTAL VOLUME:
$54.4b
24H VOL:
$216,099,358
OPEN INTEREST:
$1,189,677,720
500,754
Markets across
13,672
events
MATCHED EVENTS:
1,801
PLATFORM COVERAGE:
4
Polymarket:
51%
VS.
Kalshi:
49%
S&P 500 (SPX) Up or Down on April 2?
Description
This market will resolve to "Up" if the official S&P 500 Index closing price for S&P 500 (SPX) on Thursday, April 2, 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, April 2, 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 resolves based on absolute index level thresholds (56 distinct price levels). These markets cannot produce aligned outcomes for the same April 2, 2026 closing value.Hero Tip:
Do not assume these markets will settle identically. A Polymarket YES (SPX closes higher than April 1) could resolve alongside a Kalshi NO (if April 2 closes below all 56 thresholds, which is impossible given the lowest threshold is 5774.9999). Conversely, Kalshi will almost certainly resolve YES for any realistic SPX close above ~5775, while Polymarket's outcome depends entirely on April 1's closing price. Arbitrage or hedge across platforms only after confirming the April 1 reference price for Polymarket.Critical Divergence Points:
- Polymarket: Distinct stance: Resolves YES if SPX closes higher than the most recent prior trading day (April 1, 2026), NO if lower, and 50-50 if equal. Uses Wall Street Journal Historical Prices as source. Logic: 'This market will resolve to Up if the official S&P 500 Index closing price for S&P 500 (SPX) on Thursday, April 2, 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 April 2, 2026 exceeds any of 56 absolute price thresholds (ranging from 5774.9999 to 7249.9999); resolves NO if SPX closes at or below the lowest threshold. No reference to prior-day comparison or directional movement. Logic: 'If the end-of-day S&P 500 index value on April 02, 2026 is above [threshold], then the market resolves to Yes.'
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