The Sensex at the Bombay Stock Exchange dropped by 82 points in the late morning deals on as funds and retail investors preferred to book profits after two sessions of gains.The 30-share barometer which declined by 62 points in its opening session, was trading 82 points in the negative territory to 18,710 when reports last came in. Similarly, the wide-based National Stock Exchange index Nifty shed 23 points to 5,695.