The Bombay Stock Exchange benchmark Sensex on Thursday fell by over 40 points in early trade. The Sensex was trading at 17655, down by over 45 points when reports last came in. The wide-based National Stock Exchange index Nifty also slipped by 10 points to 5,272. Brokers said profit-booking by funds and retail investors after recent gains dragged the index down. They said flat to subdued trends on the other Asian bourses also impacted negatively the market sentiments.