The Sensex, which fell by nearly 150 points in opening trade today is still trading in the red zone. The 30-share index of the BSE that gained 191 points in the previous session fell by over 200 points to 18,140 points a short while ago. Banking, auto, realty and IT stocks leading the fall. In a similar fashion, the broad-based National Stock Exchange index Nifty lost 65 points to 5,448 points.