The Sensex opened with a positive gap of 24 points at 12,882. Fresh buying in the opening trades saw the index spurt to a high of 12,926. The index, however, could not hold gains for long and soon slipped into the negative zone.Heavy selling in mid-noon trades saw the index tumble to a low of 12,655 - down 271 points from the day's high. Some buying towards the close saw the index recover some of its losses and settle at 12,724 - down 135 points.