[whateverfor]

In theory, companies return money to their stockholders when they don't believe they can profitably invest the money internally. Large mature energy companies are a common example. Stock repurchasing is a way to hand out dividends while avoiding taxes.

For Apple, the problem is they made entirely too much money over the last decade. Apple currently has 140 Billion dollars in cash and a market capitalization of 380 billion (including the cash, so estimated value of Apple minus the cash hoard is 240 billion). That's a ridiculous amount of money, and there's no way Apple can effectively invest it, so they are giving it back to the investors so they can invest the money elsewhere.