There will be a massive market dislocation - I think that we can look at the recent LME nickel crisis to find out what the response will be like. In the nickel case, the HK/China owned LME bailed out their China whale and literally reversed the winning trades against holders such as Elliott.

Probably will be a similar response where the exchanges try to unwind catastrophic trades, but I doubt they will be successful as that would tear apart the legal/operational structure of the entire global markets. More likely, we will see a disorganized breakdown of the markets where physical gold ownership commands a premium, laws will be broken to confiscate any physical gold that countries can get their hands on, and more chaos and destruction.