The Bombay Stock Exchange benchmark Sensex fell over 77 points to 17,088 in the opening trade. The sensex was trading at 17132, down by 33 points when reports last came in. Simialrly, the national stocks exchange benchmark nifty was down by over 13 points and was trading at 5124.Brokers said weakening trend on the Asian stock markets mainly dampened the trading sentiments, triggering selling by foreign funds.Meanwhile, Hong Kong's Hang Seng index was down 0.88 per cent, while Japan's Nikkei was down 0.20 per cent in the morning trade wednesday.