Mumbai, Sep 1 - A key index of the Indian equities market built on its early morning gains around noon Tuesday to rule 1.31 percent higher than its previous close.

At 12.04 p.m., the 30-scrip benchmark index of the Bombay Stock Exchange (BSE), the Sensex, which opened firm at 15,691.27 points, was at 15,872.58 points -- 205.94 points or 1.31 percent higher than Monday's close.

Around the same time, the S&P CNX Nifty of the National Stock Exchange (NSE) too was trading in the positive terrain at 4,722.2 points, up 1.29 percent.

Broader market indices were ruling in the green as well, with the BSE midcap index trading 1.27 percent higher and the BSE smallcap index moving up 1.43 percent.

All the 13 sectoral indices on the BSE were ruling in the green, with those for auto, realty, banking and IT gaining the most.

The market breadth was positive, with 1,895 stocks on the rise, compared to 672 on the decline, and 58 remaining unchanged.