Erasing initial gains, the Sensex at the Bombay Stock Exchange was trading 90 points in the negative territory to 20,697 in late morning trade, when reports last came in. The 30-share barometer, which lost 390 points in the previous four sessions, had recovered by 75 in opening trade today.The Nifty at the National Stock Exchange index was trading 27 points in the red to 6,164.