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 April 13? Odds & Prediction Markets
Volume:
$302,524
6,850 or above 100%
S&P 500 (SPX) Up or Down on April 13? 100%
6,825 or above 100%
Closed: Apr 13, 4:00 PM EST
Polymarket
Outcome
Chance %
Price
Liquidity
Volume
24h
7d
Open Interest
Ends in
Result
Trade
Description
This market resolves based on whether the S&P 500 Index closing price on Monday, April 13, 2026 is higher ('Up'), lower ('Down'), or equal ('50-50 split') compared to the most recent prior trading day's close. The comparison uses official closing prices from the Wall Street Journal, with standard rounding to the nearest cent.
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 vs. prior trading day), while Kalshi resolves based on absolute price thresholds (50 binary contracts at 25-point intervals). These frameworks measure entirely different outcomes and will produce conflicting results for the same April 13, 2026 closing price.Hero Tip:
Do not assume these markets are equivalent. A Polymarket YES (price up from prior close) does NOT guarantee a Kalshi YES (price above a specific threshold). For example, if SPX closes at 6050 on April 13 but closed at 6100 on April 12, Polymarket resolves DOWN while Kalshi's first contract (>6049.9999) resolves YES. Verify which platform's logic matches your actual prediction before trading.Critical Divergence Points:
Polymarket:
Distinct stance: Resolves based on directional comparison between April 13, 2026 closing price and the most recent prior trading day closing price. YES if April 13 close is higher, NO if lower, 50-50 if equal. Source is Wall Street Journal Historical Prices. Quote: 'This market will resolve to Up if the official S&P 500 Index closing price for S&P 500 (SPX) on Monday, April 13, 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 based on 50 separate binary contracts, each tied to whether the April 13, 2026 end-of-day SPX value exceeds a specific absolute threshold (ranging from 6049.9999 to 7524.9999 in 25-point increments). Each contract resolves YES independently if the threshold is breached, NO otherwise. Quote: 'If the end-of-day S&P 500 index value on April 13, 2026 is above 6049.9999, then the market resolves to Yes.'
Our PredictionHero Resolution Divergence Alerts (RDA) are there to help users identify potential differences across platforms. They do not replace or supersede the official rules and description of any prediction market. Users are solely responsible for reviewing and understanding the applicable rules and resolution criteria before placing any trade or bet. If you notice a potential inconsistency, discrepancy, or error in an alert, please report it to our team so we can review and improve the accuracy of our data.
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