The Sensex opened with a positive gap of 57 points at 15479, and moved up to a high of 15,521 in morning trades. Some profit-taking, thereafter, saw the index slip into red to a low of 15,390 - down 131 points from the day's high.The Sensex, however, rebounded into the positive zone and finished (provisional) with a gain of 31 points at 15,453.