S&P 500 (SPX) Opens Up or Down on May 18?

• 01
  Price move

  Down 17pp over 24h

  Now 22¢; +9.5pp in the last hour.

• 02
  Volume pressure

  Heavy volume on this book — 24.6× turnover

  $23.9k traded against $973 of visible liquidity. The book is being worked, not just quoted.

• 03
  Active signal

  Resolution-risk observation firing

  Expires in 11h. Spread is extremely wide.

• 04
  Spread cost

  Wide spread — 11.0¢

  Bid-ask spread is wide enough that intraday moves overstate any tradeable advantage. Most of the headline pp move would be eaten by spread on a market order.

Each factor is grounded in a single named metric you can verify on this page — probability, volume, liquidity, signal, resolution state. No predictions, no prose hallucinations.

This market will resolve to "Up" if the official S&P 500 Index open price for S&P 500 (SPX) on May 18 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 open price for S&P 500 (SPX) on May 18 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 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 open/close price published by S&P 500 Index for that shortened session will still be used for resolution. If the previous trading day has 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 Open/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

Categories come from a deterministic engine: manual overrides (highest priority) → sports hard markers → event-tag rules → keyword rules → Gamma category hint → default. The engine is versioned in category-overrides.ts; methodology lives at /methodology.