Failing to maintain its initial gains for the second straight session, the Sensex at the Bombay Stock Exchange plunged 41.43 points to trade at 17,707.26 in the afternoon 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 depreciates by 12.30 points to 5,369.30 points.