TOTAL VOLUME:
$54.4b
24H VOL:
$234,875,025
OPEN INTEREST:
$1,205,330,693
501,301
Markets across
13,585
events
MATCHED EVENTS:
1,825
PLATFORM COVERAGE:
4
Polymarket:
51%
VS.
Kalshi:
49%
S&P 500 (SPX) Up or Down on March 27?
Description
This market will resolve to "Up" if the official S&P 500 Index closing price for S&P 500 (SPX) on Friday, March 27, 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 Friday, March 27, 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:
Kalshi and Polymarket use fundamentally incompatible resolution logic. Kalshi resolves YES for nearly all possible S&P 500 closing values on March 27, 2026 (covering ranges from below 6250 to above 6950), making the market logically incoherent. Polymarket resolves based on directional price movement (Up or Down) relative to the prior trading day's close, which is a completely different settlement mechanism.Hero Tip:
Do not trade this group as a unified market. Kalshi's rules appear to contain a critical design flaw—30 conditions all resolve to YES, leaving almost no outcome that resolves to NO. Polymarket's market is straightforward (Up vs Down vs 50-50 tie), but it will almost certainly resolve differently than Kalshi. Clarify the intended Kalshi resolution with the platform before placing bets.Critical Divergence Points:
- Kalshi: Distinct stance: Kalshi uses a range-based settlement model where 30 separate price bands (6250-6274.9999, 6275-6299.9999, ... 6925-6949.9999, plus below 6250 and above 6949.9999) all resolve to YES. This leaves no defined NO outcome, creating a logical contradiction. Key quote: 'If the end-of-day S&P 500 index value on March 27, 2026 is between [X]-[Y], then the market resolves to Yes' (repeated 30 times across all price ranges).
- Polymarket: Distinct stance: Polymarket uses directional comparison logic, resolving to UP if March 27 close is higher than the prior trading day's close, DOWN if lower, and 50-50 if equal. Key quote: 'This market will resolve to Up if the official S&P 500 Index closing price for S&P 500 (SPX) on Friday, March 27, 2026 is higher than the official S&P 500 Index closing price for SPX on the most recent prior trading day.'
Follow the signals, not the noise
Get insights on market conviction, notable shifts, and what the data is quietly signaling.