The Bombay Stock Exchange benchmark Sensex gained over 180 points in opening trade today. The 30-share BSE index, which has lost almost 665 points over the previous two sessions, rose by 180.04 points, or 1.09 per cent, to 16,681.78 in the first five minutes of trade this morning.In a similar fashion, the wide-based National Stock Exchange Nifty Index moved up by 47.90 points, or 0.97 per cent, to 4,994.70.