A very large call spread options trade in VanEck Gold Miners ETF (GDX) could suggest that gold prices are going to be much higher in the next six months. GDX is a popular proxy for trading gold as it is composed of the largest gold mining companies in the world. Last week, a strategist appeared to have purchased a large block call spread that expires next January. The price of gold would have to go up significantly for this call spread to end up paying off.