However, rise in index-heavyweight Reliance Industries shares and banking stocks restricted the fall.
Around 10.40 a.m., Sensex was at 52,203.55, lower by 115.05 points or 0.22 per cent from its previous close of 52,318.60.
It opened at 52,434.55 and has so far touched an intra-day high of 52,436.83 and a low of 52,192.86 points.
The Nifty50 on the National Stock Exchange was at 15,642.70, lower by 37.30 points or 0.24 per cent from its previous close.
Manish Hathiramani, technical analyst with Deen Dayal Investments said: "The Nifty is around the midpoint of the current range which is between 15,400 and 15,900. The bias continues to remain on the bullish side until 15,400 is broken on a closing basis."
"That would trigger a short-term bear phase. If we can get past 15,900, the next level to watch out for would be 16,100. Closer to the 15,400 levels a buy on dips approach can be implemented as the risk-reward ratio would be favorable."