panicR.J. O’Brien broker called about 2 pm or so, said the margin per gold contract was doubling, effective close of biz this coming Monday, from $4950 per contract to $9900 per contract. [I didn’t think to ask about silver, was so stunned].
Broker said something about the BREXIT vote this coming Thursday, and effect on gold…

CME Gold marginsThe cartel is pulling out all the stops to induce as much pain as possible through the highly levered paper metals markets.  Apparently a $100 smash in gold in 24 hours is not enough.
Moments ago, the CME announced a 25% hike in both initial and maintenance gold margins from $6,400 to $8,000, effective after market close Friday 6/21.

And so it begins.
Those who followed precious metals in 2011 will recall this game plan all too well:
Smash gold and silver prices using unprecedented amounts of naked paper shorts, then announce massive margin hikes (due to increased volatility) to force capitulation among any longs holding out. 

After large take-downs in gold and silver in thin holiday trading last week, the Shanghai Gold Exchange announced today it will raise gold margins to 13% effective Dec 28th.