The Bombay Stocks Exchange benchmark Sensex lost nearly 177 points in opening trade today. It was trading at 18,285 down by 147 points a short while ago. The wide-based National Stock Exchange index Nifty also lost 55 points to trade below the 5,500 points level.Brokers said continued offloading of stocks by funds and retail investors and fears of further monetary tightening to control inflation dampened the trading sentiment. In Asia, Hong Kong's Hang Seng Index was down 1.08 per cent, while Japan's Nikkei lost 1.24 per cent in early trade this morning. In the US, the Dow Jones Industrial Average ended 1.59 per cent lower in Wednesday's trade.