Tracking falling global markets, the Sensex at the Bombay Stock Exchange dropped 316 points, or 1.8 percent, to close below the 17,000 mark, at 16,990, today. The Nifty at the National Stock Exchange lost 93 points, or 1.8 percent, to 5,119. The market fell on sustained selling by investors, following the downgrade of US government debt by global rating agency, Standard & Poor's.Meanwhile, Gold surged 460 rupees, to breach the crucial 25,000-rupee level for the first time ever, and set a new all-time record of 25,230 rupees per ten grams at Delhi's bullion market, today, in line with a rising global trend. Silver ready spurted 1,300 rupees, to 59,900 rupees per kilo. In the overseas market, gold spurted more than 44 dollars, to a fresh record high of 1,715 dollars an ounce, as investors shifted funds from assests like equities and dollar, to gold, following downgrading of the US credit rating by Standard and Poor's.