AMAZON surprised investors on Thursday with a fourth-quarter profit that soundly beat expectations, despite a continued increase in spending and a slight sales miss, partly linked to the strong dollar. ınvestors drove shares up over 8 percent in aftermarket trading. The results seem to indicate that areas in which Amazon has been investing in heavily for years, its $99 annual loyalty program and its Amazon Web Services cloud computing offerings for businesses, are helping out its bottom line. CEO Jeff Bezos said Prime membership grew 53 percent during the year.