As noted by zerohedge, the banksters are trying their best to tame silver metal prices and shares.

Let em squirm - VHF

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PM Selloff Reason: CME To Raise Margin Requirements For Silver From $5,000 to $6,500

Tyler Durden

November 9, 2010

And if that doesn't work, there is always confiscation.

"CME confirmed silver margins raised from $5000 to $6500 (30%) effective 11/10 settl - no other metals effected"

Presumably, this affects the maintenance margin. And is a lovely way to kill paper longs.... but not shorts, of course.