Apple's fourth fiscal quarter, which ends Sept. 30, is the same as the third quarter of the calendar.
The fly in the ointment, however, is that Apple has already exhausted its supply of the iPhone 5S, its flagship smartphone priced starting in the U.S. at $199 with a contact, $649 without one.
Within hours of the iPhone 5S sales kick-off Friday, Apple ran through its supply, first at its online store then at its brick-and-mortar outlets.
Cook acknowledged the iPhone 5S shortages.
"The demand for the new iPhones has been incredible, and while we've sold out of our initial supply of iPhone 5S, stores continue to receive new iPhone shipments regularly," Cook said in his statement today. "We appreciate everyone's patience and are working hard to build enough new iPhones for everyone."
The iPhone 5S currently shows "October" as the projected ship date of new orders, but the iPhone 5C will ship within 24 hours, Apple's website noted Monday.
Marshall of ISI said it was "hard to determine how quickly supply will ramp to meet robust demand."
But iPhone shortages are nothing new: When the iPhone 5 went on sale a year ago, the company drained stocks within an hour and shoved back shipping dates by two weeks. It sometimes takes months for Apple to reach a supply and demand balance.
Marshall raised his estimate of 2013 iPhone shipments from 152 million to 173 million to a higher range of 160 million to 190 million based on the opening weekend number. His revised estimate of 36 million iPhones for the third quarter would represent a 34% increase over the same period last year.
By 1 p.m. ET today, Apple's stock had climbed 4.4%, or $20.42, on the sales news.
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