for me the most interesting phrase in those reports was: " that gold is lumped in with FX."

re your question, i can't give you any concrete information as a few years ago i stopped spending as much time on inside baseball, but for at least a decade there have been articles about the trillions of derivatives exposure of the big banks. the banks always say that they're just carrying offsetting exposures or hedges for their clients and that their own exposure nets near zero. that's what they say.