Apple sold $6.5 billion in bonds on Monday to fund its share buyback programme.
The California technology giant had initially planned to offer $5 billion worth of bonds, but boosted the offer due to strong demand.
Apple aims to return more than $130 billion to shareholders this year. While Apple has large cash reserves of $178 billion ($142 billion when debt is taken into account), most of this money is held abroad; Apple would therefore have to pay 35% corporation tax if returning the money to the U.S.
The decision to borrow the money instead taps into low corporate borrowing costs.
The activity caused shares in Apple to rise 0.9%. The sales come in the wake of Apple announcing the largest quarterly corporate profits ever last week.