The benchmark indices, which surged in opening session, have given up all their early gains to trade lower by around 0.5 per cent each at mid-session on Thursday.
At 11:53 am, the Sensex was down 304 points or 0.50 per cent at 60,955, while the Nifty fell 88 points or 0.48 per cent to 18,178.
The top gainers on the Sensex were Kotak Bank, Power Grid, HDFC, NTPC and ICICI Bank, while the laggards were led by Dr Reddy's, HCL Tech, Asian Paints, TCS and REliance.
Earlier, the Sensex jumped over 250 points in opening trade, tracking gains in index majors HDFC twins, Kotak Bank and Infosys amid a largely positive trend in global markets.
In the previous session, the 30-share index ended 456.09 points or 0.74 per cent lower at 61,259.96, and Nifty dropped 152.15 points or 0.83 per cent to 18,266.60.
Foreign institutional investors (FIIs) were net sellers in the capital market, as they offloaded shares worth Rs 1,843.09 crore on Wednesday, as per exchange data. (with inputs from PTI)