The Sensex, which had gained 35 points in the previous session, fell by 123.71 points to below the psychological level of 18,000 points at 17,868.29 after Hero Honda posted its first drop in quarterly profit in almost three years and oil and gas major ONGC's quarterly net income declined by 25 per cent.
Similarly, the broad-based National Stock Exchange index Nifty fell by 41.30 points to 5,367.60, after touching an intra-day low of 5,349.20.Selling pressure gathered momentum following a fall in Asian stock markets and a lower opening in Europe, with the London's FTSE-100 index shedding 0.30 per cent to 5,298.29.
In the 30-BSE index components, 22 stocks declined, while eight ended with gains. Barring mid cap and small cap sectors, all sectoral indices finish in the negative zone.
The benchmark index has lost 1.1 per cent this week, its first decline in four weeks, trimming its monthly advance to 1.3 per cent.
Continuing its losing streak, index heavyweight Reliance Industries lost 0.08 per cent to Rs 1,009.60 in today's session, following a 4.1 per cent fall over the previous two sessions.
The second most valuable firm, Infosys dipped by 1.60 per cent to Rs 2,788.85.
Hero Honda fell by Rs 55.10 to Rs 1,815.40 after a 72 per cent rise in the cost of raw materials such as steel and rubber dented its income for the quarter.ONGC fell to Rs 1.221.10 during intra-day after first quarter income fell 25 per cent. However, it managed to recoup its losses and end 5 paise up at Rs 1,242.55.
GAIL India declined by Rs 14.25 to Rs 438.20 after BNP Paribas downgraded the stock to "hold" from "buy".
Software exporting companies like Tata Consultancy Services, Infosys and Wipro fell after glum forecasts from US technology companies and downbeat comments from a US Federal Reserve official.
The realty sector index suffered the most, losing 1.40 per cent to 3,372.93, followed by the tech index, which fell by 1.22 per cent to 3,400.59. The capital goods sectoral index fell by 1.14 per cent to 14,591.67, while the information technology index shed 1.13 per cent to 5,474.84.
With investors and funds shifting their money towards to small and medium cap stocks as a safe haven, the midcap sector index rose by 0.35 per cent to 7,407.91 and the smallcap index by 0.20 per cent to 9,348.97.