The 30-share BSE index, which has lost nearly 800 points over the previous three sessions, fell by 71.30 points, or 0.44 per cent, to 16,396.14 in the first five minutes of trade Wednesday.
In a similar fashion, the wide-based National Stock Exchange Nifty index lost 13.45 points, or 0.27 per cent, to 4,927.50.
Capital goods, banking, power, oil and gas and metal stocks bore the brunt of the selling pressure, dragging down the stock market indices.
Brokers said continued selling by funds and retail investors over concerns that the Reserve Bank of India may announce another hike in interest rates later this week was mainly responsible for the poor start on the bourses this morning.
They said concerns about the euro zone sovereign debt crisis also had a negative impact on the trading sentiment.
Meanwhile, in the Asian region, Hong Kong`s Hang Seng Index rose by 0.96 per cent, while Japan`s Nikkei Index shed 0.20 per cent in early trade Wednesday.