In early trade, the 30-share index rose to a day's high of 28,115.96 points on the back of a stronger global market on hopes of a Greece deal and buying by foreign investors.
However, on across-the-board selling towards the close, the Sensex slipped into negative zone and closed the session 75.07 points or 0.27 per cent down at 27,945.80, slipping from its two-and-a-half months high.
The gauge had gained 376 points in previous two sessions.
Tata Motors fell the most among Sensex stocks by dropping 1.84 per cent despite the firm reported a 6 per cent increase in total sales in June, followed by Hindalco at 1.72 per cent.
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Other major losers on the index included Cipla, ONGC, Vedanta, Maruti Suzuki, GAIL, HDFC Bank, Dr Reddy's, Infosys, HDFC, NTPC, Lupin, L&T, Tata Steel, TCS and Sun Pharma.
However, shares of M&M, Bharti Airtel, Bajaj Auto, Hero MotoCorp, Axis Bank, Wipro, HUL, ITC and RIL ended in positive zone and cushioned the fall.
Out of 30-share Sensex, 20 ended lower.
Stocks related to irrigation segment such as Finolex Industries, Jain Irrigation Systems, Shakti Pumps, Kaveri Seeds, Monsanto India, Dhanuka Agritech and Advanta surged up to 8 per cent after the government decided to spend Rs 50,000 crore under the Pradhan Mantri Krishi Sinchai Yojna.
Sectorally, the BSE metal index fell the most by plunging 0.62 per cent, followed by IT (0.41 pc), healthcare (0.40 pc), realty (0.19 pc) and capital goods (0.13 pc).