Mumbai, Sep 3 - A key index of the Indian equities markets gave up the slender gains it had managed in the afternoon to end 88 points in the red Thursday.

The 30-scrip sensitive index (Sensex) of the Bombay Stock Exchange (BSE), which opened at 15,539.34 points, ended at 15,378.54 points (provisional), down 88.92 points or 0.57 percent.

The broader-based Nifty of the National Stock Exchange (NSE) followed the Sensex to end at 4,590.55 points, down 0.39 percent.

Broader market indices, however, ended up on the gaining side, with the BSE midcap index closing 0.36 percent higher and the BSE smallcap index ending 0.8 percent down.