Reliance, Infosys, ICICI Bank, L&T and SBI were the negative contributors to the Sensex.
The Sensex was down 129.16 points or 0.71pc at 18037.87, and the Nifty was down 33.80 points or 0.62pc at 5418.30.
The total traded turnover of the markets stood at Rs 1,23,854.7 crore.
Top gainers on the BSE Midcap: Wockhardt, Trent, Tube Investment, BF Utilities and Tata Chemicals were up 5-18pc.
Top losers on the BSE Midcap: Hind Nat Glass, Pipavav, Essar Shipping, Shree Cements and Gammon India were down 4-5pc.
Top gainers on the BSE Smallcap: Jagatjit Industries, Ajmera Realty, Varun Industries, REI Six Ten and JVL Agro Ind were up 10-20pc.
Top losers on the BSE Smallcap: Ankur Drugs, Sequent Scienti, Kothari Product, Rainbow Papers and Garware Offshore were down 8-16pc.
Nifty struggles in trading
Nifty was trading in a low range around 5400-5450.
At 1:50 pm, the Sensex was down 43.29 points or 0.24 percent, at 18123.74, and the Nifty was down 27.70 points or 0.51 percent at 5424.40. About 1574 shares advanced, 1482 shares declined, and 321 shares remain unchanged.
Power Grid, PNB, Sterlite Industries, HUL and Maruti Suzuki were the gainers at 1-4 percent up among the largecap.
However, Suzlon Energy, Reliance Communications and Jaiprakash Associates were among the losers at 2-6 percent down.
Trent, Wockhardt, Tata Chemicals were the gainers among midcap with 6-16 percent.
Jagatjit Industries, Ajmera Realty, Varun Industries were the gainers among the smallcap with 11-20 percent up.
Nifty continues trading in narrow range
50-share NSE Nifty continued its trading on a quiet note of narrow range between 5442-5465.
At 12:04 pm, the Sensex was trading at 18182, up 16 points and the Nifty was at 5458, up 6 points. The Nifty Aug future was trading at 9 points premium.
The shares of BHEL, Infosys, Cipla, SBI, ICICI Bank, ONGC, Ambuja Cements and Jindal Steel were under pressure.
However, shares of Reliance Industries, TCS, DLF, L&T and ACC were supporting the benchmarks since opening trade.
Tata Chemicals was up 4.7-8 percent among midcaps and Shree Cements, Info Edge, Hind Nat Glass were among the losers with 3-4 percent down.
Nifty begins on a flat note
Nifty once again began on a flat note and the index was vibrating around Rs 5450 level.
At 9:01 am, the Sensex was trading at 18196, up 29 points and the Nifty was at 5462, up 10 points. About 541 shares advanced while 198 shares declined on NSE.
Power Grid, HDFC Bank, Hindalco, ITC, Tata Motors, Unitech were the gainers among the frontliners.
Jaiprakash Associates and Sterlite Industries, however, were witnessing selling pressure.
Reliance Communications was down 2.5 percent.