[a-posteriori]

Apple's fiscal year (internal accounting year) ends Sept, 30th instead of being aligned with the calendar year.

[secabeen]

This is very common for companies with holiday-linked or time-linked sales. It's much easier to make your big chunk of sales in Q1 (October-December for Apple), then have the rest of your fiscal year to spend that money. Getting all your revenue in Q4 is much harder to budget around.

[kshacker]

BTW it is not 'exactly' September 30, it is usually last Saturday in September. So it does not even align at a 'calendar month' boundary.