The BSE-30 share index resumed lower at 21,289.15 points, and hovered in a range of 21,333.66 to 21,230.03 before quoting at 21,247.94 at 1030 hours.
Sensex had gained over 310 points in the previous four sessions. It showed a loss of 125.72 points, or 0.59 per cent, from its last close.
The NSE 50-share barometer Nifty also fell 39.10 points, or 0.62 per cent, to 6,306.55 at 1030 hours.
Asian stocks extended losses in their early trade tracking overnight losses in the US.
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Key benchmark indices in Japan, South Korea, Singapore and Hong Kong were down 0.48 to 1.63 per cent, while indices in China and Taiwan rose 0.06 to 0.85 per cent.
US stocks closed sharply lower yesterday as weak economic data from China prompted investors to sell resource stocks and emerging-markets assets and seek safety in bonds, gold, and high-dividend paying sectors.