A strong pull-back rally of 115 points today, after some listless trading sessions in the last few weeks, saw the Bombay Stock Exchange Sensex close above the 5,500-mark.The rally was also triggered by overnight strong gains on the US bourses, smooth settlement cycle of the March futures contract on Thursday and expectations of strong full-year earning numbers, which will be out from April.The Sensex, after opening on a positive note at 5,448.29 points, which also happened to be the day’s low, ended at 5,528.94 points, up 114.50 points. On the National Stock Exchange (NSE), the broader 50-share Nifty closed at 1,747.50 points, up 43.05 points.‘‘There is no proper reason for the sharp rally witnessed on Friday. The overnight gains on the Nasdaq and in Dow Jones, and smooth F&O settlement cycle on Thursday may have aided the rally,’’ said Sashi Krishnan, CIO, Cholamandalam AMC.