Shares of capital goods, banking, refinery, realty and PSU firmed up on good buying enquiries.
The Sensex opened higher at 20,522.36 and firmed up further to a high of 20,601.62 before quoting at 20,588.95 at 1015 hours, showing a gain of 168.69 points of 0.83 per cent from its last close.
The NSE 50-share Nifty also firmed up by 52.60 points or 0.87 per cent to 6,109.70 at 1015 hours.
The market may remain volatile today as traders roll over positions in the futures & options (F&O) segment from the near-month November 2013 series to December 2013 series. The near-month Nov 2013 derivatives contracts expire today.
Asian stocks edged higher in their early trade after US employment and consumer confidence reports boosted optimism in the world's largest economy. Key benchmark indices in China, Hong Kong, Indonesia, Taiwan, South Korea, Singapore, and Japan were up 0.06 to 1.31 per cent.