The BSE benchmark Sensex was almost flat, down by 3 points a short while ago. It was trading at 19,990 points. The stock market lost over 40 points in the opening trade on emergence of profit booking at existing higher levels but was hovering around the 20,000 level.Similarly, the wide-based National Stock Exchange Nifty index was trading at 6,001 points, down by 11 points. In the opening trade, Nifty fell by 20.40 points to 5,991.30 points.