Silver prices plunged and gold prices slipped ahead of the New York day.
Both metals had sold off even more sharply in early Asian trade before news broke of the death of al Qaeda leader Osama Bin Laden. Spot silver lost 12% in 11 minutes shortly after the open of Asian trade, while spot gold fell 2.2% in 40 minutes.
The U.K. market is closed Monday for a holiday.
Traders in Sydney disagreed about the trigger for the move down, one of the sharpest ever for a market for which fluctuations of more than 1% are unusual.
One trader argued that a rise in the margins required by CME Group Inc. to trade Comex silver futures had sparked the selloff, which was then accentuated by the absence of many traders for the holiday.
Ahead of the New York day, silver was down $2.57, or 5.4%, to $45.37 U.S. a troy ounce, and gold was down $8.90, or 0.6%, at $1,556.80 U.S.
Silver has doubled in price since last August and quadrupled since late 2008, while gold is also at more than double its $681.75/oz low in the wake of the 2008 financial crisis.
Spot platinum down $15, or 0.8%, at $1,858 U.S. an ounce after briefly scraping a new post-financial crisis record at $1,884.50 U.S./oz, while palladium fell $3, or 0.4%, at $786 U.S. an ounce.
