After rising to 21,017.45 at open, the BSE Sensex fell back sharply to trade lower by 185.10 points, or 0.89 per cent, to 20,674.76 at 1000 hours.
The US Federal Reserve said it will cut its monthly stimulus programme by USD 10 billion, bringing it down to USD 75 billion.
Selling pressure was seen in banking, capital goods and oil and gas sector index.
The 30-share index Sensex had gained 247.72 points in yesterday's trade following RBI decision to keep interest unchanged.