Tracking melt down in the global equity market, the Bombay Stock Exchange benchmark Sensex tumbled 472 points at the mid-session in Mumbai on Tuesday on heavy selling by funds spread over a wide front.
The Sensex, which remained weak in the last three trading sessions, dropped by 471.50 points to 12,859.01 at 1300 hrs as heavy-weight stocks like Reliance Industries, Reliance Petroleum, BHEL and HDFC Bank recorded hefty losses.
The wide-based National Stock Exchange index Nifty plunged 121.10 points to 3918.60, as almost all 50 stocks in its kitty remained at lower levels.
IT majors Infosys and Satyam were moderately higher in both the indices.
Markets across Asia fell on worries over US mortgage firms while selling pressure gathered momentum after the Hong Kong Stock Exchange dropped 3.2 per cent in the morning session.
Markets across Asia struggled despite US government's announcement on Sunday to give bigger credit lines to financing giants Fannie Mae and Freddie Mac, which offer vital support to the multi-trillion-dollar US mortgage market.