The Sensex opened 52 points lower at 16,687, and soon slipped to a low of 16,598. Fresh buying in capital goods stocks helped the index rebound into the positive zone.The index touched a high of 16,854 - up 256 points. The Sensex finally ended (provisional) with a gain of 48 points at 16,788.The NSE Nifty moved up 13 points to close (provisional) at 5,050.