Fortune's Philip Elmer-Dewitt calculated that the company spent $16 billion last quarter ($4 billion in cash, $12 billion through the so-called accelerated share repurchase program) to purchase 36 million of its own shares at an average price of just over $444.
That kind of money is enough for Apple to have bought Nokia or BlackBerry three times over.
In his Apple Q3 RY13 Review, Asymco analyst Horace Dediu says, "One way to think of it is this is Apple's greatest acquisition ever."
Elmer-Dewitt notes that most of the shares (22 million) were retired last quarter. Apple currently has about 908 million shares outstanding.