The Sensex opened with a positive gap of 98 points at 15,359 on the back of positive global cues. The index rallied nearly 200 points ahead of the announcement of the Credit Policy quarterly review.A 50bps hike in Cash Reserve Ratio (CRR) saw the index tumble into the negative zone to a low of 15,225. The index, however, soon bounced back as the markets cherished the fact that all key banking rates were left unchanged in the policy review. Aggressive buying towards the end saw the index zoom to a high of 15,569 - up 344 points from the day's low. The Sensex finally ended with a smart gain of 290 points at 15,551.