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%

BETA
Dashboards
polymarket
kalshi
Trending

S&P 500 (SPX) Up or Down on April 15?

Volume:
$309,945
Outcome
Chance %
Price
Liquidity
Volume
24h
7d
Open Interest
Ends in
Result
Trade

Description

This market will resolve to "Up" if the official S&P 500 Index closing price for S&P 500 (SPX) on Wednesday, April 15, 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 Wednesday, April 15, 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 (60 distinct price levels). These frameworks produce different outcomes for identical market conditions.

Hero Tip:

Do not assume these markets will resolve identically. On April 15, 2026, the SPX could close higher than April 14 (Polymarket YES) but below all Kalshi thresholds (Kalshi NO), or vice versa. Arbitrage is impossible because the underlying resolution logic is incompatible. Verify which platform's framework matches your actual market view before trading.

Critical Divergence Points:

  • Polymarket: Distinct stance: Resolves based on directional comparison between April 15, 2026 closing price and the most recent prior trading day closing price. 'This market will resolve to Up if the official S&P 500 Index closing price for S&P 500 (SPX) on Wednesday, April 15, 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 absolute index level thresholds on April 15, 2026. Contains 60 separate YES conditions, each triggered if end-of-day SPX exceeds a specific price level (ranging from 6124.9999 to 7599.9999). 'If the end-of-day S&P 500 index value on April 15, 2026 is above [threshold], 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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PredictionHero © 2026 · v0.13.0PredictionHero provides aggregated market data and informational signals only. Nothing on this site constitutes financial, legal, or investment advice. Markets are volatile and speculative. Past performance does not guarantee future results. Always do your own research and consult qualified professionals before making decisions involving risk.