Posting its biggest single-day fall in nearly seven weeks, the Sensex at the Bombay Stock Exchange plunged 324 points, or 1.2 percent, to close at 26,493, today. The Nifty at the National Stock Exchange slumped 109 points, to end below the 8,000-mark, at 7,933. Stock markets in Japan, China, Hong Kong and Singapore declined between 0.2 percent and 1.8 percent. But the rupee rose 8 paise, to 61.05 against the dollar, on dollar selling by exporters.Gold rose 10 rupees, to 27,460 rupees per ten grams in Delhi. Silver advanced 100 rupees, to 41,600 rupees per kilo. And Brent crude oil futures remained below 98 dollars a barrel, while US crude fell 22 cents, to 92.70 dollars a barrel.