Doing so would incur a large tax liability when transferring the funds back to the US. The reason Apple has been taking out bonds in the US instead of repatriat

Doing so would incur a large tax liability when transferring the funds back to the US. The reason Apple has been taking out bonds in the US instead of repatriating the overseas cash reserves is because it's cheaper to do the former to pay a dividend or perform a share buyback.