Nasdaq 100 (NDX) Up or Down - October 15

This market will resolve to "Up" if the official Nasdaq 100 (ticker: NDX) closing price on Wednesday, October 15, 2025 is higher than the official opening price for NDX on the same day. This market will resolve to "Down" if the official closing price for NDX on that date is lower than the official opening price. If the official NDX opening price and closing price are exactly equal, this market will resolve 50-50. Note that all figures will be rounded to the nearest cent using standard rounding. If there is no official opening price for NDX on the specified date (for example, due to a trading halt before market open, system issue, delisting, or other disruption), the market will use the first valid on-exchange trade price of the regular session as the effective opening price. If there is no official closing price for NDX on the specified date (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. If NDX does not trade at all during the regular session, the market will resolve 50-50. The resolution source for this market is Nasdaq 100 Index, specifically the Open and Close values published at https://www.wsj.com/market-data/stocks under "Historical Prices".

How trading works

Polymarket uses a central limit order book (CLOB) model — you can buy or sell shares of any outcome at the current market price, or place limit orders at your target price. All positions are settled in USDC when the market resolves.

Resolution

Markets resolve through UMA's Optimistic Oracle. After the market closes, a proposer submits a resolution, followed by a 2-hour dispute window. If no dispute is raised, the resolution is accepted. Disputed markets go to UMA token holder vote.