Caution ahead of expiry of October month contracts in the derivatives segment tomorrow also influenced sentiments.
The 30-share barometer was down by 156.11 points or 0.57 per cent to 27,097.33 in early trade.
The index had lost 217.37 points in the previous two straight sessions.
All the sectoral indices led by banking, realty and capital goods were trading in the negative zone, falling up to 0.94 per cent.
The NSE Nifty slipped below the 8,200-mark by losing 51.90 points or 0.63 per cent to 8,181.00 in early trade.
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Investors are awaiting the US Federal Reserve's policy statement which could provide clues about the timing of an interest rate hike.
Among Asian markets, Shanghai composite was quoting 0.91 per cent lower, Hong Kong's Hang Seng shed 0.72 per cent, while Japan's Nikkei up by 0.60 per cent in early trade today.
The Dow Jones Industrial Average ended 0.24 per cent lower in yesterday's trade.