Mumbai, Aug 4 - A key index of the Indian equities markets slipped into the red soon after opening higher Tuesday and was ruling 54 points down, about five minutes into trading.

The sensitive index (Sensex) of the Bombay Stock Exchange (BSE) opened higher at 15,940.10 points, as against Monday's close at 15,924.23 points. But it soon slipped to 15,869.66 points, 54.57 points or 0.34 percent down.

The broader S&P CNX Nifty of the National Stock Exchange (NSE) was also ruling in the negative terrain at 4,692.05 points, a fall of 0.41 percent.

Broader market indices were however in the green, with the BSE midcap index trading 0.48 percent higher, and the BSE smallcap index up 0.71 percent.