Tim Cook emails Jim Cramer to say everything's fine

Tim Cook took the extraordinary step of reassuring investors that Apple's business is doing just fine despite the fact that global markets are cratering. 

In an email exchange with CNBC star Jim Cramer, Cook said iPhone sales have accelerated in China over the past few weeks:

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Apple is getting vaporized, falling by more than 20% from its highest levels.

Markets globally are tanking based largely on things happening in China. The Chinese economy has looked weak. With China being the second largest iPhone market, investors were naturally worried about the state of the iPhone.

"I think it's a classic fear of the unknown," Piper Jaffray analyst Gene Munster said in a previous interview with Business Insider. "In this case specifically it's the fear of what's happening in China. Investors appear to be concerned about what the impact is from China, and if that ends up translating to more broader concerns or a slowdown from consumers."