TOTAL VOLUME:
$54.6b
24H VOL:
$283,259,638
OPEN INTEREST:
$1,235,549,422
505,521
Markets across
13,661
events
MATCHED EVENTS:
1,892
PLATFORM COVERAGE:
4
Polymarket:
51%
VS.
Kalshi:
49%
S&P 500 (SPY) closes above ___ on April 23?
Volume:
$257,943
Outcome
Chance %
Price
Liquidity
Volume
24h
7d
Open Interest
Ends in
Result
Trade
Description
S&P 500 (SPY) closes above ___ on April 23?
PredictionHero - Resolution Divergence Alerts (RDA)
Divergence Detected
Issue:
Polymarket and Kalshi resolve on different underlying assets (SPY ETF vs S&P 500 Index) with different data sources, closing mechanics, and price precision. While both measure the same economic event (market level on April 23, 2026), the settlement values will not be identical due to ETF tracking error, index composition, and data source differences.Hero Tip:
Treat these as two separate markets with correlated but non-identical outcomes. SPY closing at $735 does not guarantee the S&P 500 Index closes above any specific level on Kalshi. Use historical SPY-to-Index ratios to estimate cross-platform convergence, but do not assume arbitrage-free pricing. Polymarket offers superior transparency (Pyth source is named and auditable); Kalshi's data source is opaque. If you trade both, hedge for basis risk.Critical Divergence Points:
- Polymarket: Resolves on SPY (ETF) closing price via Pyth data. YES if close > strike price (e.g., $735). Uses Pyth 1-minute candle for final minute of regular trading; falls back to last valid Pyth price or official exchange close if Pyth data unavailable. Exact equality resolves NO. No trading day resolves 50-50. Source explicitly named: Pyth (https://pythdata.app/explore/Equity.US.SPY%2FUSD).
- Kalshi: Resolves on S&P 500 Index end-of-day value. YES if index > strike (e.g., 7724.9999). Uses 0.0001 precision thresholds. No fallback mechanism, data source, or no-trading-day rule specified in provided documentation. Settlement source is unspecified.
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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