Shares of Apple are rising by more than four percent on word that Carl Icahn, the billionaire activist investor trying to take over Dell, has made a large investment in company behind the iPhone and the Mac.

Icahn announced via Twitter that he has made an “large position” in Apple and thinks it is “extremely undervalued.” He didn’t disclose how large his position in Apple is nor what he thinks the company is actually worth. Presumably that information will come to light in regulatory filings.

Icahn also said he had spoken with Apple CEO Tim Cook today.

“We appreciate the interest and investment of all our shareholders, Apple said in a statement given to AllThingsD. “Tim had a very positive conversation with Mr. Icahn today.”

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Before today Apple shares had fallen by more than 12 percent since the start of 2013, and 33 percent since reaching their historic high of $700.09 in 2012.

via AllThingsD » Mobile http://allthingsd.com/20130813/carl-icahn-makes-a-large-investment-on-apple/