The Sensex is down nearly 180 points from its previous close. This despite a rally from a rough opening when it fell about 205 points. This is in tandem with a weakening trend on other Asian bourses amid global recession worries. All the sectoral indices, led by metal, realty, banking and auto stocks, were in the red, dragging the Sensex near the crucial 16,000 points mark.The National Stock Exchange Nifty index also plunged by 61.60 points.