The Bombay Stock Exchange index Sensex plunged by 334 points at midsession today after frantic selling by funds in blue-chip stocks such as Tata Steel and Reliance Industries.
The 30-share index was trading at 14,188.25 at 1400 hrs, a fall of 334.59 points over the previous close.
The BSE barometer had lost 435 points on Wednesday.
The wide-based National Stock Exchange index Nifty dipped below its supporting level of 4,300 points falling by 134 to 4,222.15 points.
Market-heaviest Reliance Industries plunged by 1.45 per cent after UBS cut its rating, saying falling refining margins would dent earnings. Tata Steel was trading lower 6.19 per cent over the previous close.
Marketmen said refinery shares were down on rising crude oil prices, raising concerns over easing profit margins.
The metal sector stocks dropped on melting base-metal prices in the overseas markets, they added.