Continuing its slide for the third straight session, the Bombay Stock Exchange benchmark Sensex lost 113 points in opening trade. This follows sustained selling triggered by weak global markets.The 30-share index, which had lost 343 points in the previous two sessions, fell further to 20,476 points, as realty, metal, auto and banking stocks remained under pressure. The wide-based National Stock Exchange index Nifty also declined by 31 points to 6,163.45 points.Stock brokers said weak trend in other Asian markets following overnight losses at the US markets dampened the trading sentiment. However, expectations of encouraging industrial output data for September quarter, due to be released later today, capped the losses.Hong Kong's Hang Seng Index was down 1.28 per cent, while Japan's Nikkei index fell by 0.38 per cent in morning trade.In the US, Dow Jones industrial average ended 0.65 per cent down in Thursday's trade.