Erasing initial gains, the Sensex at the Bombay Stock Exchange was trading 24.58 in the negative territory at 17,724 in late morning deals.Earlier, Sensex recovered by almost 52 points in early trade on buying by funds and retail investors which took cues from firming trends on the other Asian bourses.Similarly, the broad-based Nifty of the National Stock Exchange scaled down by 11.10 points to 5,370.50 points.