After rising over 150 points in early trade on the back of a firming trend in global markets coupled with covering-up of short positions by speculators, the Sensex fell back to trade down by 206.85 points, or 0.74 per cent, to 27,494.94 at mid-session as profit-booking wiped off initial gains.
Major losers that pulled down the Sensex and Nifty were metals, realty, consumer durables, oil & gas, IT, PSU, power, healthcare, banking and auto sector stocks.
Similarly, the National Stock Exchange index Nifty, after rising to 8,364.75 at the outset, succumbed to widespread profit-booking and slipped below the 8,300-mark to quote lower by 63.65 points, or 0.76 per cent, at 8,260.35.
Brokers said emergence of profit-booking by funds in stocks that had recently logged gains amidst absence of any fresh trigger and a weak trend at other Asian markets led to the fall in markets.
Meanwhile, foreign portfolio investors (FPIs) sold shares worth a net Rs 335.24 crore yesterday, as per provisional data from stock exchanges.