For the most part, Apple already had what people wanted even before Cook took over. They iterated on those and their market valuation grew. My question is how

For the most part, Apple already had what people wanted even before Cook took over. They iterated on those and their market valuation grew. My question is how is the "value" of 90% of Apple's market valuation "created"? How come a single day in any company can see their "value" rise by 24%? What of value is created with an announcement that wasn't there the day ago?