After commencing the day on a strong note with gains of over 83 points, the 30-share index plunged by 350.32 points to fall below the 19,000-level to 18,942.88 at 1130 hrs.
However, it recovered part of the losses to trade at 19,068.78, still down by 224.42 points at mid-session after Finance Minister P Chidambaram asserted there is no crisis and that government enjoyed majority and it was "absolutely stable".
Brokers said the market sentiment was battered on reports of the ruling UPA government's key ally DMK pulling out its support, which came close on heels of RBI policy announcement.
The RBI today cut its short-term lending rate by 0.25 per cent to spur growth and revive investment but sounded a note of caution on further easing of rates on account of high food inflation and current account deficit.
They said the market partly recovered as domestic funds came in for rescue and Chidambaram assuring that there is no threat to the government.