The Sensex plunged over 400 points at mid-session on Monday on fears that rising inflation in the US will curb spending and limit further interest-rate cuts, thus slowing investment into emerging markets.
The BSE 30-share index, Sensex, which remained weak during the last two trading sessions, fell by 402.44 points to 19,628.39 at 1330 hours with most of the heavyweight shares declining.
The wide-based National Stock Exchange index, Nifty, too dipped by 158.95 points to 5,888.75.
Trading sentiment also turned bearish following a fall in overseas markets.
In the US the Standard and Poor's 500 Index dropped 1.4 per cent on Friday, which pulled down most of the Asian stock markets this morning.