Sensex gained 1,779.60 points or 11.51 per cent in the straight fourth week as also in the current month, between January 2 to January 27, 2012.

Buying was seen across-the-field as barring realty, other 12 sectoral indices closed with sharp to moderate gains between 5.64 per cent and 0.71 per cent, while 20 out of 30 Sensex-based scrips registered increase in their values.

The first day of the week saw some lacklustre activity but on the second day investors' confidence surged after the Reserve Bank of India in its third quarter monetary policy review cut the cash reserve ratio (CRR) by 50 basis points to infuse liquidity in the system, keeping the short-term lending rate unchanged.

The move will pump Rs 32,000 crore into the financial system, and gives signals of a cut in the lending rate in the near future.