who served as the company’s chief operating officer before Jobs stepped down. As CEO, Cook has taken a more hands-on approach in the world’s most populous country, visiting China multiple times to meet with government officials and survey Apple’s factories there. Even more important than the trips is the deal Cook inked last year with China Mobile, the world’s largest wireless carrier, to carry the iPhone. His focus on the country has paid off handsomely. China is now Apple’s fastest-growing sales market by far, generating $5.9 billion in revenue in the most recent quarter.