The Sensex at the Bombay Stock Exchange plummeted 469 points, or 2.5 percent, to 18,089 in afternoon trade as selling pressure intensified after the rupee tumbled to a new intra-day low against the dollar. Earlier in the morning, the Sensex had opened with a loss of 221 points, or 1.2 per cent, at 18,337, as investors sold stocks after three sessions of gains, amid weak global bourses. The Sensex had climbed over 650 points in the previous three trading sessions.Stock markets in Japan, Singapore, Taiwan, Hong Kong, Indonesia and South Korea had lost between 0.1 percent and 3.4 percent, today. The US Dow Jones Industrial Average had ended 0.4 per cent lower in yesterday's trade.