Continuing its losing streak for the fourth straight day, the benchmark BSE Sensex on Friday fell by 163 points to 20,872 in early trade on sustained selling by funds and retail investors amid weak industrial output data for October and jump in retail inflation.The 30-share index had lost 401 points in the previous three sessions.It moved further down with banking, capital goods, realty, oil and gas and power sector stocks retreating.The wide-based National Stock Exchange index Nifty fell 52 points to 6,185.In the Asian region, Hong Kong's Hang Seng index rose 0.39 per cent, while Japan's Nikkei gained 1.01 per cent in early trade on Friday.The US Dow Jones Industrial Average ended 0.66 per cent down in Thursday's trade.