The Sensex at the Bombay Stock Exchange remained weak in afternoon trade, and had fallen 153 points, or 0.7 percent, to 21,018 a short while ago. Earlier in the morning, the Sensex had declined 120 points, or 0.6 percent, to 21,051, on sustained selling by funds, amid weak regional bourses. The Sensex had lost 155 points in the previous two trading sessions. Stock markets in Japan, Taiwan, South Korea, Indonesia, Singapore and Hong Kong had lost between 0.3 percent and 1.1 percent on Thursday, on concerns that the US Federal Reserve, or central bank, may act sooner than expected to unwind its monetary stimulus after a provisional budget deal in Washington. The US Dow Jones Industrial Average had ended 0.8 per cent lower in Wednesday's trade.