Back in April, Apple announced that it will invest $60 billion in repurchasing its own shares from the public by 2015. Even now, it remains the largest authorized share buyback in history...
Source: http://www.phonearena.com/news/Apple-acquires-a-16-billion-stake-in...-Apple_id45722
Source: http://www.phonearena.com/news/Apple-acquires-a-16-billion-stake-in...-Apple_id45722