(CNN) -- World leaders are often measured by what they do in their first 100 days in office. But what about business leaders? As of Friday, it has been 100 days since Apple co-founder and longtime CEO Steve Jobs passed the company torch to Tim Cook. Since that first day, August 24, Wall Street and legions of Apple fans have had their gazes fixed on Cook. As the man heading arguably the most influential and valuable technology company in the world, Cook wields a great deal of power. After Cook took over, Jobs held the role of executive chairman but lost his long battle with cancer some six weeks later, on October 5. The day before Jobs died, Cook led a news conference to announce the iPhone 4S.
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Friday is Tim Cook's 100th day as official Apple CEO
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Cook took over for Steve Jobs on August 24, 2011
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Analysts say Cook has passed his first tests as Apple's leader
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Even without @placeholder' dramatic stage presence, the iPhone 4S became the fastest-selling phone over its launch weekend, selling 4 million units worldwide.
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People who have worked with @placeholder at Apple describe him as quiet and confident, the peacekeeper at the conference room table.
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@placeholder was hands-on in product development and had a knack for identifying which markets were ripe for invasion.
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"It's going to be business as usual for Apple in @placeholder's absence," he said.
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The first half will be made available to him five years from when @placeholder officially became CEO, and the rest will vest five years after that, as long as he stays.
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Cook had promised in a recent e-mail to his staff that @placeholder wouldn't change under his leadership, but he introduced at least one corporate program that would have been out of character for Jobs.
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In September, @placeholder began matching employees' charitable contributions up to $10,000.
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Now, he will need to continue to build on @placeholder' steady foundation.