The Sensex opened with a small positive gap of eight points at 8,543, but soon dropped to a low of 8,537. Buying emerged at lower levels in noon deals, and the Sensex zoomed to a high of 8,650 - an intra-day swing of 113 points.
The Sensex finally closed with a gain of 103 points (1.2%) at 8,638.
The Nifty gained 36 points to close at 2,609.