An article asks whether Apple's huge buyback could be better used - perhaps in developing new products.
The motivations for a buyback are complex (and responding to Karl Icahn's pressure may be one), but in terms of a simple IRR analysis, a buyback generates a return of about 3% + 0.8*5% = 7% for shareholders. This is the expected return on AAPL stock (using the the CAPM).
While I am sure Apple has plenty of interesting research and development projects, it might be the case that returning money to shareholders so that they can invest it, rather than keeping it money market securities provides the best return. Shareholders are then free to reinvest this money in other firms which might be seeking dollars to finance their R&D programs.
RF = 3%
Market Risk Premium = 5%
AAPL Beta = 0.8