The Sensex opened with a negative gap of 137 points at 15,950 on the back of weak cues from the global markets. Weakness in the first half of the day saw the index slip to a low of 15,869.The index, however, recovered and rebouned into the positive zone in mid-noon trades and touched a high of 16,111 - up 242 points from the day's low. The Sensex, however, could not hold gains and slipped back into red to finish (provisional) with a loss of 36 points at 16,050.The NSE Nifty ended (provisional) 11 points higher at 4,839.