The 30-share barometer Sensex resumed higher at 20,478.67 and firmed up further to 20,503.86 on initial buying in select counters amid fresh foreign capital inflows.
However, it declined immediately to 20,346.97 at 1030 hours due to fresh selling, showing a loss of 101.52 points or 0.50 per cent from its last close.
The NSE 50-share index Nifty also dropped by 29.10 points or 0.48 per cent to 6,054.90 at 1030 hours.
Major losers were - Cipla Ltd 5.40 pct, Coal India 2.02 pct, Oil & Natural Gas Corp (ONGC) 1.52 pct, HDFC 1.47 pct, Tata Power 1.46 pct, BHEL 1.30 pct, Wipro 1.17 pct, SBI 1.08 pct and HDFC Bank 1.05 pct.
Asian stocks dropped in their early trade after the recent advances.
Key benchmark indices in Japan, Hong Kong, South Korea, Indonesia and Taiwan fell by 0.06 to 0.98 per cent; while indices in Singapore and China were up by 0.08 to 0.36 per cent.