Buy Apple on better iPhone sales growth, UBS says

Investors should buy Apple shares on the prospect of a shorter iPhone upgrade cycle than expected, according to UBS, which reiterated its buy rating.

"Given positive pre-order data, aggressive US carrier promotions, and positive supply chain chatter, we have somewhat more confidence that the upgrade cycle may not be lengthening as much as previously thought," analyst Steven Milunovich wrote in a note to clients Tuesday.