The Bombay Stock Exchange benchmark Sensex rose for the fifth straight day today adding over 51 points on sustained buying interest whetted by attractive corporate earnings so far. The Sensex, which had gained 293 points in last four trading sessions, added 51.08 points to close at 17,745.28 points. A firming trend in the Asian region and better opening in Europe further fuelled the up trend. The wide-based National Stock Exchange index Nifty rose by 18.35 points to 5,322.45 points.