Markets extended losses in late-noon trades on weakness in realty, IT and metal sectors. Negative cues from global markets also took the bourses lower.
The Sensex touched a low of 18,679 towards the end of the day, and finally ended at 18,721 - down 137 points.
Nifty ended down 44 points at 5,616.
Asian markets were in red on a higher-than-expected unemployment data from the US. Hang Seng slipped 1.6% to 22,347. Nikkei was down 0.7% at 10,069.
Straits Times, Seoul Composite and Taiwan Weighted was down around 1% each.
The earnings season has begun with HDFC announcing its quarterly numbers on Friday.
The housing mortgage lender reported a 22% y-o-y growth in net profit to Rs 844.53 crore for the April-June quarter of the current fiscal.
The stock was down around 0.6% at Rs 708.
The next result to watch out for is IT bellweather, Infosys, which is set to come out on Tuesday. The stock declined 2% at Rs 2,919 - the biggest dragger in the benchmark. other IT stocks - TCS and Wipro dropped 1-2% each.
In other news, the government has set a target of merchandise exports of $300 billion in the fiscal year through March 2012, after shipments topped the government's estimate and rose to a record high of $245.9 billion last year.
Finance Minister Pranab Mukherjee on Friday, 8 July 2011, said the government's revenue collections so far have been healthy and he doesn't expect any slippage in the fiscal year target of Rs 7.9