At 12.25 p.m, the Sensex was trading down 51.91 points or 0.17% at 30,382.88 with 22 components falling.
The benchmark BSE Sensex tumbled 223.98 points or 0.73 percent to 30,434.79, while the broader Nifty index fell by 96.30 points or 1.01 percent to 9,429.45.
FMCG stocks hogged the limelight after the GST Council fixed rates for most of the items.
Shanghai Composite shed 0.06 per cent.
JSW Steel's net profit zoomed to Rs 1,003 crore from Rs 367 crore in the corresponding period last year while income from operations rose 60 percent to Rs 16,952 crore as against Rs 10,615 crore in the year-ago period, the company said in a statement. The BSE AUto index was down 1.2 per cent; Cummins India, Maruti Suzuki, Mahindra & Mahindra, Eicher Motors, MRF and Bosch were among the losers from this space. London's FTSE rose 0.52 per cent.
Meanwhile, foreign portfolio investors (FPIs) bought shares worth Rs 235.33 crore yesterday, while domestic institutional investors sold shares worth Rs 65.77 crore, according to provisional data released by the stock exchanges.
State Bank of India, the country's biggest lender by assets, rose 1.7% to 308.15 rupees on Friday and added about 4% for the week, after posting a 123% increase in on-year in net profit for the quarter ended Mar.31.
Coal India rallied 2.6%, followed by NTPC and PowerGrid as the GST rate on the hydrocarbon was pegged at 5% as compared with the current tax burden 11.69%, which will make electricity cheaper.
The S&P BSE mid-cap index fell 0.72 per cent while the small-cap index declined 0.88 per cent.
Further, a host of changes have been made in BSE 100, BSE 200, BSE 500, Sensex Next 50 and sectoral indices such as Teck and carbonex.
BSE 100 index would see Bajaj Finserv, Petronet LNG, Piramal Enterprises, Shree Cement, MRF, Container Corp Of India, Pidilite Industries, Havells India, Bharat Electronics, Apollo Hospitals Enterprise and IDFC Bank coming in.