Carl Icahn isn't the only billionaire investor with an appetite for Apple's stock.
Financier George Soros more than doubled his stake in the iPhone and iPad maker in recent months, according to regulatory documents filed on Wednesday.
Soros' fund held 66,800 shares of Apple Inc stock at the end of June, up from 26,800 shares in March.
Apple's stock finished Wednesday at $US498.50 ($A549.52), its highest closing price since January 23.
At that price, Soros' holdings are currently worth about $US33 million ($A36.38 million).
Apple's shares remain nearly 30 per cent below their peak of $US705.07 reached nearly 11 months ago.
Despite that drop, Apple remains the world's most valuable company with a market value of more than $US450 billion.
Soros' disclosure about his increased interest in Apple came a day after Icahn took to his Twitter account to announce he has built a large stake in the Cupertino, California, company, too.
Icahn hasn't yet specified how much Apple stock he owns, but he has already urged Apple CEO Tim Cook to increase the amount of money that the company is spending to buy back its stock.
Apple so far has pledged to spend $US60 billion buying back its stock by end of April.
Unlike Icahn, Soros hasn't indicated that he intends to pressure Apple to do things differently.
Both investors have built vast fortunes by making savvy investments.
Forbes magazine estimates Icahn's wealth at $US20 billion and Soros' at $US19.2 billion.
Soros is making an even bigger bet on one of Apple's biggest rivals, Google Inc.
He ended June with 396,953 Google shares in his portfolio, up from 337,271 at the end of March, according to Wednesday's regulatory filing.
Google's stock closed on Wednesday at $US869.81, valuing Soros' holdings at about $US345 million.
The growing popularity of smartphones and tablet computers running on Google's Android operating system slowed the sales growth of iPhones and iPads, contributing to the decline in Apple's stock.