The Sensex resumed higher at 21,260.15 and firmed up further to 21,304.70 on initial support on the back of good foreign capital inflows and firm Asian cues.
However, it declined afterwards to 21,123.30 before quoting at 21,182.50 at 1030hrs, showing a loss of 11.08 pts or 0.05 per cent from its last weekend's level.
The NSE 50-share Nifty also moved down by 11.15 points or 0.18 per cent to 6,302.65 at 1030hrs.
However, SSLT rose by 1.52 pc, Tata Motors 1.36 pc, Coal India 1.17 pc and Dr Reddy's Lab 1.04 pc.
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Foreign institutional investors (FIIs) bought shares worth a net Rs 295.76 crore on last Friday as per provisional data from the stock exchanges.
Asian stocks climbed in their early trade with Japan's Nikkei 225 Stock Average poised for its biggest annual gain since 1972, as the yen touched a five-year low versus the dollar.
Key benchmark indices in China, Hong Kong, Indonesia, Japan, Taiwan, South Korea and Singapore were up 0.03 pc to 0.99 pc.