Got this message from IB a little bit ago:

To NYMEX,NYSELIFFE traders:

Wed May 4 10:50:37 2011 EST

Margin Increase: Silver Derivatives

In light of the recent unprecedented volatility in silver markets, the exchanges that offer trading in silver derivative contracts are increasing the margin requirements on these products. In an effort to adequately address the inherent risk resulting from this volatility, we are increasing margin requirements on silver derivative contracts to a level exceeding that which the exchanges are implementing.

You will be notified as more information becomes available.

Please monitor and manage your risk accordingly.

They're not even telling what the margin will be!

Someone correct me here if I'm in error, but if margin requirements are increased to 100%, doesn't this effectively eliminate the paper market in COMEX silver?