Apple came under attack yesterday from one of its biggest shareholders over the $137 billion cash pile it’s accumulated over the last few years, in yet another sign of growing investor unrest over the company’s poor performance in recent months, reports the Wall Street Journal.

David Einhorn, the billionaire hedge fund manager of Greenlight Capital, is reportedly agitating for action against the company, pressing shareholders to resist Apple’s proposed plans for its cash pile, which are set to go to a vote on February 27.

In a carefully worded letter to his fellow shareholders, Einhorn calls on them to vote against the proposal that would make it much harder for Apple to issue preferred stock, which is one of the most common ways in which cash-rich companies can return money to their shareholders.

Instead, Mr. Einhorn, whose investment firm owns about $610 million worth of Apple, suggests that the company should instead distribute “perpetual preferred” stock that would pay shareholders a dividend yield of 4%. This would see shareholders receive more cash back from Apple as it pays out a bigger yield than regular shares, which currently carry a 2.3% dividend yield, reports the WSJ. He adds that new investors may even be willing to pay a higher premium for Apple shares, if the company decided to issue preferred stock.

“It’s a unique solution to a problem that’s been intractable—how does Apple reward its shareholders?” said Mr. Einhorn to the WSJ.

“This idea allows them to keep their cash and yet enables shareholders to recognize value.”

The shareholder action and the growing scrutiny of Apple’s performance underline how its status has quickly changed from one of a growth stock to that of a value stock, as far as investors are concerned. Apple shares, which were for a long time the darling of Wall Street, have taken a tumble of late amid questions about the company’s stalled growth and lack of innovation. In the last few months, Apple shares have shed more than a third of their value, from a previous high of $700 a share last summer.

As well as writing a letter to shareholders, Mr. Einhorn, via his investment firm Greenlight, has filed a lawsuit against Apple in the Federal Courts that seeks to make Apple strip down its proposals so that shareholders will be allowed to vote on each provision, something that is “mandated by SEC rules”, according to Reuters.

The WSJ reports that Einhorn first came to prominence in 2007 when he made a fortune buying against Lehman Bros before its well-publicized collapse. He is thought to be one of the most influential among a group of Apple investors that have become increasingly impatient with the company and its practice of hoarding its cash. Much of this wealth is held in low-yield investments, such as Treasuries, and many investors are eager to see some of that cash returned so that they can invest it elsewhere for better returns.