The Sensex at the Bombay Stock Exchange plunged 449 points, or 2.3 percent, to close below the 19,000-mark, at 18,733, on all-round selling, today, as the rupee dropped to a new all-time intra-day low against the dollar. The Nifty at the National Stock Exchange plummeted 143 points, or 2.5 percent, to 5,542.Stock markets in Japan, China, Hong Kong, South Korea and Singapore ended mixed.