Mumbai, Aug 10 - A key index of the Indian equities markets fell back into negative terrain Monday afternoon amid volatile trading.

At 1.50 p.m., the 30-scrip sensitive index (Sensex) of the Bombay Stock Exchange (BSE), which opened at 15,287.14 points, was at 15,111.12 points, down 49.12 points or 0.32 percent.

Similarly, the Nifty of the National Stock Exchange (NSE), too, was trading in the red at 4,467.3 points, down 0.31 percent.

Broader market indices were also in the negative terrain with the BSE midcap index 0.47 percent down, while the the BSE smallcap index was 0.89 percent lower.