After a lower start, the Sensex plunged by 524.09 points to 18,034.04 at 1300 hrs as the rupee hit a new record low of 65.94 (intra-day) against the dollar.
On similar lines, the wide-based National Stock Exchange index Nifty dropped by 163.75 points to 5,312.75, led by stocks of banking and capital goods sector.
Brokers said the foreign funds remained net seller which gathered momentum sparked by the rupee hitting new record low levels.
All sectoral indices, barring information technology exporters and teck on expectations of higher revenue following stronger dollar, remained in red zone.
Major losers were State Bank of India, HDFC Bank, ICICI Bank, BHEL, Larsen and Toubro, Coal India, Hero MotoCorp, Hindalco, ITC, Maruti Suzuki, NTPC, Sun Pharma and Bharti Airtel.