The Bombay Stock Exchange benchmark Sensex opened lower by 182 points on Friday on heavy selling by funds. The 30-share index was trading at 16,075, down by over 231 points when reports last came in. Similarly, the National Stock Exchange index Nifty fell by 69 points to quote at 4,791points. Market men said investors sold shares on fears that RBI in its monetary policy review later in the day may hike interest rates to stem the rising inflation. Trading sentiment also weakened on falling trend in global markets.