Profit-booking from operators after cautious stance from Global rating agency Standard and Poor as well as weak service sector activity in last month pulled the Sensex down.
India's services sector contracted for the fourth successive month amid economic uncertainty. The HSBC/Markit purchasing managers' index for the services industry was at 47.1 in October from 44.6 in September. An index value of below 50 indicates contraction.
The Sensex resumed higher at 21,278.08 and rose to its all-time high level of 21,321.53 during Muhurat trading due to persistent foreign inflows as well as confidence given by the Finance Minister P Chidambaram that the country's current account deficit will be contained below USD 60 billion in current financial year.
But, it declined afterwards to 20,600.90 before ending the week at 20,666.15, showing a loss of 530.66 points or 2.50 percent on fears of downward ratings by S&P. The NSE 50-share Nifty also dropped by 166.45 points or 2.64 percent to end at 6,140.75.
Banking stocks suffered the most led by heavyweight SBI which tumbled by 7.19 percent following its decision to hike lending rates by 0.20 percent. However, IT shares firmed up on account of stronger than expected results from Cognizant and a weak rupee that fell below 62-level against the US dollar.