The stand off between the government and its key Left allies on the nuclear deal issue has started casting a shadow on the stock markets, whose benchmark Sensex lost over 259 points in midsession on emergence of selling by funds in bluechip stocks.
The Sensex, which recovered significant ground in the last two sessions, taking cues from global bourses, after the US Federal Reserve's cut the rate at which it lends to banks by half a percentage point, fell into negative territory by losing 259.04 points to 14,181.24 at 1300 hours.
In a similar fashion, the National Stock Exchange's Nifty dropped by 84.35 points to 4,124.70.
The fall was in the aftermath of growing differences between the government and the Left parties over Indo-US civil nuclear deal, stock brokers said.
Infosys, the nation's second-largest software exporter, fell by Rs 41, or 2.24 per cent, to Rs 1,788 while ICICI Bank, the country's second-biggest lender, declined Rs 23,95, or 2.75 per cent to Rs 848.
State Bank of India, the largest state-run bank fell Rs 51.45, or 3.3 per cent, to Rs 1,499 and Reliance Industries dropped by Rs 16.65, 0.93 per cent at Rs 1,775.10.
The four stocks account for about one-third of the Sensex's weight.