The Bombay Stock Exchange benchmark Sensex on Wednesday fell 148 points to close below the 20,000-level, as investors locked in profits judging the 12 per cent rally in last four weeks an overdone.
The 30-share index closed lower by 148.52 points, at 19,956.34 points. The barometer had climbed 14 per cent this year to regain the 20,000-level after 32 months and becoming the best performer among the world's ten biggest markets.
The broad-based National Stock Exchange index Nifty dipped below the crucial 6,000-level, losing 38.20 points to 5,991.30 points.
Brokers said major players indulging in booking profits at existing higher levels and adjusting their portfolios ahead of the September contract expiry in the derivatives segment on Thursday, mainly pulled down the market.
Investors turning cautious on weak European trends further influenced the trading sentiment, they added.
The BSE metal sector index, led by Sterlite Industries, fell the most, losing 1.92 per cent to 16,726.94 points.
Sterlite plunged 8.50 per cent to Rs 161.50, its biggest drop since July 2009, after a court ordered to close its copper plant for breaching environment standards.
Hindustan Zinc fell 3.37 per cent to Rs 1,090.55 on heavy profit-booking by investors.
The oil and gas sector index fell 0.81 per cent to 10,570.45, as the largest state-owned oil explorer ONGC dropped 2.35 per cent to Rs 1,422.60.
In the BSE 30-index components, 23 closed with losses, while seven scrips ended in the positive zone.
(With inputs from PTI)