As Apple's annual shareholder meeting approaches, some big investors are waging an increasingly public and heated fight over what the tech behemoth should do with its massive cash hoard.
Activist investor Carl Icahn is waging a proxy fight to push the Apple board to use a substantial part of its $158 billion cash reserve to buy back company shares, thus boosting the stock price.
While the California Public Employees' Retirement System, the largest state public pension fund in the country, which owns $1.6 billion in Apple stock—dismisses Icahn's strategy as short-term thinking that won't help the company create new and innovative products.
Apple declined to comment.
This fight is becoming public as Apple nears the annual shareholder meeting on Feb. 28, and the company is recommending that shareholders reject Icahn's proposal. (Still, Apple has committed to returning $100 billion to shareholders, just over a longer period of time than Icahn proposes.)
Anne Simpson, senior portfolio manager of investment at CalPERS, agrees with Apple's plans and takes exception to Icahn's activist investing approach.
"Now, standing outside and lobbing a brick through a window really is not a sensible way to engage in the conversation. We don't think Carl Icahn, who's a relatively small investor with a very short-term agenda, should be steering the board of Apple, which is a very big company, with a long-term future which many people are relying on," Simpson told CNBC.
And Icahn is firing back at Simpson, saying that she is misguided.
(Read more: Slow down Carl: Not all Apple shareholders want an big share buyback)
"It's a shame that Anne Simpson is more interested in spewing pejoratives than improving corporate governance in this country, which CalPERS is in a position to do," Icahn, chairman of Icahn Enterprises, told CNBC in an exclusive interview.
He went on to say his activist investment style has been highly successful and it's critical to keep pressure on companies to make them accountable to shareholders. Icahn, for his part, doesn't appreciate the assertion that he's a short-term investor.
Icahn said he is often a long-term holder. For example, he has owned his Biogen shares since 2007 and Federal Mogul since 2001
Icahn and CalPERS have very different investment objectives. Icahn buys significant stakes in companies and then rattles the boardroom cage in an effort to instigate change.
CalPERS is a large institutional investor, and represents the long-term interests of California state public employees. It has assets of $277 billion and tends to buy and hold, and is focused on steady returns.
Simpson is concerned that Icahn's vocal activism doesn't serve the best interests of long-term Apple shareholders.
(Read more: Apple drops 5% on weak iPhone sales, revenue outlook)
"I think this is more sound and fury than sensible advice, and what really needs to happen is the long-term owners should be there backing Apple in a rational, sensible and efficient deployment of capital. We don't want the company to be distracted by short-term noise," Simpson added.
Icahn says the name of the game for serious investors is delivering returns, and his track record is impressive.
Icahn Enterprises, over the past 10 years, has posted an annualized return of 26.6 percent.
(Read more: Apple board advises vote against Icahn's buyback proposal)
Over the last 10 years, through Oct. 31, 2013, CalPERS generated an annualized return of 7.1 percent.
It's still not entirely clear how all of this is going to play out at Apple's shareholder meeting.
One thing that is clear: Carl Icahn and Anne Simpson won't be sitting next to each other at the meeting.
—By CNBC's Mark Berniker and Josh Lipton. Follow them on Twitter @markberniker and @CNBCJosh.