TOTAL VOLUME:
$54.4b
24H VOL:
$218,201,443
24H TRANSACTIONS:
527,797,601
OPEN INTEREST:
$1,191,873,651
500,842
Markets across
13,663
events
MATCHED EVENTS:
1,809
PLATFORM COVERAGE:
4
Polymarket:
51%
VS.
Kalshi:
49%
S&P 500 (SPX) Up or Down on March 16?
Volume:
$282,908
Outcome
Chance %
Price
Liquidity
Volume
24h
7d
Open Interest
Ends in
Result
Trade
Description
This event group tracks whether the S&P 500 Index closes higher or lower on March 16, 2026 compared to the prior trading day (Polymarket) versus absolute price thresholds on that date (Kalshi). The two platforms use fundamentally different resolution mechanics: one measures directional movement, the other measures absolute index levels.
PredictionHero - Resolution Divergence Alerts (RDA)
Divergence Detected
Issue:
Polymarket uses relative directional movement (vs prior trading day close) while Kalshi uses absolute index value thresholds. The same March 16 closing price will resolve differently on each platform depending on the prior day's close and which Kalshi threshold applies.Hero Tip:
Do not assume these markets are interchangeable. Polymarket Up/Down is purely relative; Kalshi Yes/No is purely absolute. If SPX closes at 6500 on March 16 but closed at 6600 on March 15, Polymarket resolves Down while Kalshi may resolve Yes (if 6500 exceeds the applicable threshold). Arbitrage is impossible; treat as separate instruments.Critical Divergence Points:
- Polymarket: Directional comparison framework. Resolves Up if March 16 close > most recent prior trading day close; Down if lower; 50-50 if equal. Source: Wall Street Journal Historical Prices. Key quote: 'This market will resolve to Up if the official S&P 500 Index closing price for S&P 500 (SPX) on Monday, March 16, 2026 is higher than the official S&P 500 Index closing price for SPX on the most recent prior trading day.'
- Kalshi: Absolute threshold framework. Resolves Yes if March 16 end-of-day SPX value exceeds any of 60 specified thresholds (ranging 5899.9999 to 7374.9999 in 25-point increments). No No outcome specified; appears to be a ladder of Yes conditions. Key quote: 'If the end-of-day S&P 500 index value on March 16, 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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