Silver and gold futures fell sharply Monday after the Chicago Mercantile Exchange, one of the world’s largest trading floors for commodities, asked traders to put up more cash to make bets on precious metals with prices surging this year. This year, gold futures are up 65% and silver has more than doubled. The CME raised margin requirements for gold, silver and other metals in a notice posted to the exchange’s website Friday. These notices require traders to put up more cash on their bets in order to insure against the possibility that the trader will default when they take delivery of the contract. Exchanges ... (full story)