The Sensex after rising to 27,150.78 points in the early trade succumbed to profit-booking and slipped below the 27,000 mark for the first time since September 5. The index fell 126.37 points, or 0.47 per cent, to trade at 26,931.04 in the late morning trade.
The NSE 50-share Nifty also slipped by 32.50 points, or 0.40 per cent, to 8,061.60 after rising to 8,127.95 in early trade.
Stocks of healthcare, metal, auto, IT, oil and gas and consumer durables sector succumbed to profit-booking, dragging the key indices down.
Brokers said the market turned volatile and participants preferred to book profits at every rise and buying pace also slowed down to some extent.
They said the reports about foreign funds and domestic institutional investors turned sellers yesterday also dampened sentiments.
Meanwhile, Foreign Portfolio Investors (FPIs) sold shares worth a net Rs 9.91 crore yesterday, as per provisional data from the stock exchanges.