Billionaire investor Carl Icahn said he thinks Apple shares were "extremely undervalued." He suggested executing a bigger buyback. However, analysts said raising Apple's buyback in a short period of time would be short sighted.

The second quarter earnings report of Apple showed it raised its stock buyback project to USD60 billion. The move was said to be the biggest corporate buyback in the history of the United States. Apple also increased its quarterly dividend by 15% to USD3.05 for every share. This would result to USD100 billion total cash return to stockholders within the next three years.

According to analysts, Apple must allot some cash to fund its research and development and run its daily operations. Putting majority of its cash to a program that would fund a larger buyback would not make sense. Apple currently has USD146.5 billion in cash. Icahn said the smartphone maker could borrow more money to support an expanded buyback program.

Ben Reitzes, Barclays Capital's analyst, said it could be likely that Icahn made a plan for the overseas cash of Apple. Much of the cash of the tech titan is international which has always been an issue when doing bigger buybacks and dividends. "As a result, it could also be possible that Mr. Icahn has suggestions for a faster plan and even has plans for overseas cash that are not yet evident to investors," Reitzes noted.