Investors are optimistic that Apple's earnings report coming after the closing bell Tuesday will beat expectations, but what happens to iPhone demand in the next quarter is the big question.
Apple's stock has enjoyed a very strong run. In the past 12 months, it has surged some 45 percent. And it's coming in red hot for this earnings report: In just the past five days, the stock is up over 6 percent. (It's down slight in premarket trading Tuesday.)
Of course, a lot of the enthusiasm has to do with iPhone demand.
The iPhone still generates over half of the company's revenues and accounts for an estimated two-thirds of its gross profits.
Analysts at RBC think that Apple shipped nearly 64 million iPhones in the last quarter. That would imply 25 percent year-over-year growth.
But what happens in the months ahead, specifically during the first and second quarters?