Nadex calculates prices for commodities using a continuously updated average of recent prices, called the indicative price. This price is designed to indicate the current market price in a way that's useful for traders. Nadex uses the same calculation to calculate the expiration value of its contracts, which is compared to the strike price.
Gold Chart https://www.tradingview.com/symbols/XAUUSD/ Silver Chart https://www.tradingview.com/symbols/XAGUSD/ Natural Gas Chart https://www.tradingview.com/symbols/UNGUSD/ Crude Oil Chart https://www.tradingview.com/symbols/USOUSD/ (Click on the "Full Chart" tab or the "Fullscreen mode" option.)