"Nobody could have foreseen this. Nobody. At this point there is nothing left to comment on what is a concerted action to "mitigate" any and all risk in the commodity market but could as well be classified as executive order 6102.5. While we were joking before that soon one will have to post more cash than an silver contract is worth, we are now forced to reevaluate this sarcasm."
Read more at Zero Hedge, Here:
http://www.zerohedge.com/article/cme-hikes-silver-margins-17-4th-hike-8-trading-days
