There is less and less gold in the COMEX vaults, especially the gold classified as "Registered". This category comprises gold, which is being used in the futures market transactions. On September 18 there were only 162,034 registered ounces of gold. Having in mind that the current open interest in futures contracts is standing at 42,410,400 ounces, the physical gold stored at COMEX covers only 0.38% of gold, which is in the game. This is the smallest fraction since many years (or even ever). Please, look at the chart below:
Simply put, there is practically no physical gold to back up a virtual futures market, which is an extraordinary bullish (for gold) situation.