Mumbai, July 31 - A key index of the Indian equities markets opened in the green Friday taking cues from its Asian peers and a good showing by the US markets Thursday. It was ruling 255 points up about five minutes into trade.

The sensitive index (Sensex) of the Bombay Stock Exchange (BSE) opened at 15,449.47 points, as against Thursday's close at 15,387.96 points, and then moved further up to 15,643.74 points, 255 points or 1.66 percent up.

The broader S&P CNX Nifty of the National Stock Exchange (NSE) was also ruling in the positive terrain at 4,646.25 points, a gain of 1.64 percent.

Broader market indices were also in the green, with the BSE midcap index trading 1.57 percent higher, and the BSE smallcap index up 1.37 percent.