MUMBAI: The benchmark S&P BSE sensex on Tuesday plunged 590 points to end below the 18,000 mark as the rupee fell past the 66-mark to a lifetime low and concerns were raised about the subsidy burden after passage of the Food Security Bill.

Chaos returned to the stock markets after three sessions of gains as foreign funds sold heavily. Investor sentiment was unchanged after finance minister P Chidambaram said the fiscal deficit would be contained at 4.8% of GDP even after doling out subsidies to implement the Food Security Bill.

The 30-share sensex remained in negative terrain since the opening and touched a low of 17,921.82 before ending at 17,968.08, a fall of 590.05 points or 3.18%. In the previous three sessions, the index added 652.22 points.

The broader Nifty on the National Stock Exchange slumped 189.05 points or 3.45% to 5,287.45. The SX40 on the MCX-SX closed down 391.41 points at 10,629.77.

"The Food Security Bill was passed yesterday, which is expected to add to the fiscal burden," said Sanjeev Zarbade, VP at Kotak Securities. "We believe crude oil has emerged as a key risk in the near term, which is not a good sign for the rupee. Thus, on an overall basis, the macroeconomic outlook has weakened and risks have clearly strengthened."

Reports said Brent crude was close to a 5-month high amid tension after a suspected chemical weapons attack in Syria.

Investors lost Rs 1.7 lakh crore in wealth as 1,538 stocks closed lower and 719 advanced.