The Sensex on Thursday declined 247 points to extend the losses for the third day in succession on sustained selling by funds on fears that rising inflation would force the central bank to hike interest rates again.
After regaining the 18,000-point level at the outset, the Bombay Stock Exchange 30-share index closed down 247.37 points to 17,693.18, its lowest level in more than six weeks.
All sectoral indices, led by realty, auto and metal, ended in the red on across-the-board selling.
The broad-based National Stock Exchange index Nifty, too, lost 73 points to end the day at 5,331.80.
Meanwhile, food inflation crossed the 8 per cent mark for the week ended July 23 triggering fear among investors that the Reserve Bank of India might tighten the monetary policy further which could impact the economic growth.
Analysts said already earnings reported by eight out of 19 of Sensex companies have lagged behind market estimates for the first quarter of this financial year.
Trading sentiment was also dampened on weakening Asian trend and lower opening in Europe.