The Bombay Stock Exchange benchmark Sensex fell by over 155 points in opening trade today. This follows investors locking in gains in yesterday's session amid a weak trend on other Asian bourses. However, an early rally in stocks of Reliance Industries, the most valuable scrip in the 30-share Sensex pack, cushioned the fall. The 30-share barometer, which rallied by 227 points in yesterday's volatile session, declined by to 18,283 points in the first few minutes of trade today as auto, realty and banking stocks succumbed to selling pressure. In a similar fashion, the wide-based National Stock Exchange Nifty index slid by 52 points to 5,467 points.Hong Kong's Hang Seng index was down by 1.52 per cent and Japan's Nikkei lost 1.03 per cent in early trade today.