The BSE benchmark Sensex fell by over 72 points in early choppy trade today, extending its losses for the fourth straight session. The 30-share barometer, which has lost over 438 points in the previous three sessions, moved down further by 0.40 per cent, to 17,798 in early trade today. Stocks of technology, power, metals and auto companies remained under pressure, which pulled down the Sensex.Similarly, the wide-based National Stock Exchange Nifty index slid by over 14 points to 5,351.Market experts said, the trading sentiment remained bearish on concerns of rising interest rates and reports of lower advance tax collections by the government.