When Carl Icahn shifts his investments around, the industry watches. The billionaire investor and head of Icahn Enterprises has such a major influence on other investors around him that the simple mention of his investment decisions can cause stock prices to move one direction or the other. Thus, when it comes time for the quarterly 13-F reports which firms like Icahn's are required to submit to the SEC and which detail holdings in a variety of areas at the end of the previous quarter, analysts look closely to see how Icahn has changed his strategies in the past few months. The most recent round of 13-F reports, documenting holdings at the end of the fourth quarter of last year, have recently been released, and it appears that Icahn has made some significant shifts in his positions.

Exiting Voltari

One of the biggest changes in Icahn's portfolio from the last quarter of 2016 was that the billionaire sold off his shares of tech company Voltari (VLTC). Voltari, formerly called Motricity, had been in Icahn's holdings since 2007. In 2015 Icahn bought up 4.06 million shares of stock in the company at the bargain price of $1.36 per share, following a period in which the company issued a rights offering. By this time, Icahn's investment has fallen by just over 4%, although the total stock price of Voltari has plummeted by about 90% since it hit a high just over $19 per share in mid-2015.

Picks up Hertz, Trims Paypal and Others

When Icahn sold off his stake in Voltari, he used those assets to invest elsewhere in the same period. According to the 134-F, Icahn Enterprises doubled its stake in Hertz Global Holdings (HTZ) to a total of 29.2 million shares. Icahn also picked up additional shares in Herbalife (HLF), the embattled nutritional company. Icahn has been in a longstanding and highly publicized fight over the viability of Herbalife with fellow activist investor and hedge fund billionaire Bill Ackman. By the end of 2016, Icahn's stake in the nutrtiional company was 22.5 million shares, a value of more than $1 billion.

At the same time, Icahn also sold off portions of his positions in other names, including PayPal (PYPL), Freeport-McMoRan (FCX), and Nuance Communications (NUAN). All of these stocks remain in Icahn's portfolio, but their relative weight has been dropped to make room for other areas of investment.

Icahn, known throughout the industry as a cunning and activist-minded investor, typically buys up large stakes in target companies in an effort to sway the business practices of those companies. The latest 13-F does not immediately suggest new targets for Icahn's strategies, although it seems likely that the investor has larger plans in mind.