The Sensex, which had lost 498 points in past two days, declined further by 56.57 points, or 0.29 per cent, to 19,748.19 -- the lowest close since 19,676.06 on July 11.
Brokers said investors refrained from creating major positions before RBI credit policy scheduled on July 30.
They also said market participants feared that the RBI's recent liquidity tightening measures to curb weakening rupee might hurt economic growth prospects in the short-term.
The broad-based National Stock Exchange index Nifty dipped below another crucial level of 5,900 this week by losing 21.30 points, or 0.36 per cent to 5,886.20. Also, SX40 index, the flagship index of MCX-SX, fell by 37.91 points, or 0.32 per cent, to end at 11,791.25.
State Bank of India, the country's biggest lender, dropped by 1.93 per cent, ICICI Bank by 0.32 per cent and HDFC Bank by 1.45 per cent, Others like Yes Bank and Axis Bank also ended lower.
Hindustan Unilever, an Indian unit of the world's second-biggest consumer-goods company, plunged by 3.38 per cent after lower quarter earnings, said analysts.
The metal sector index suffered the most by losing 3.52 per cent, followed by realty sector index (1.59 per cent), Public Sector Undertaking sector index (1.50 per cent) and Banking index (1.43 per cent) fared badly.
