The Sensex at the Bombay Stock Exchange lost 129 points, or 0.8 per cent, to 16,333 within the first five minutes of trade, this morning, on sustained selling by investors, amid weakness in the global markets. Later the Sensex fell further, and stood 188 points, or 1.1 percent in negative territory, at 16,273, in afternoon deals. The 30-share Sensex has already lost more than 1,100 points in the past six trading sessions.Regional markets also continued to fall, with key stock indices in Japan, China, Hong Kong, Indonesia, South Korea, Taiwan and Singapore down by between 1 percent and 2 percent, today, amid fresh worries about Europe's debt crisis. The US Dow Jones Industrial Average lost 1.1 per cent in yesterday's trade.