At the stock markets, after a very weak opening, the Sensex at the Bombay Stock Exchange lost considerably more ground, and had plunged 434 points, or 1.4 percent, to 31,489, a short while ago. The Nifty at the National Stock Exchange had slumped 138 points, to 9,826. Selling pressure was seen across the board. Key regional stock markets in China, Hong Kong, Singapore and South Korea had fallen between 0.1 percent and 1.4 percent, amid geopolitical worries, and concerns about the Chinese economy. And at the forex market, the rupee had weakened 16 paise, to 64.95 against the dollar in afternoon deals.