(Reuters) - Fund manager David Einhorn's Greenlight Capital on Thursday said it has sued Apple Inc and said the company needs to do more to unlock value for shareholders.

Einhorn said Greenlight filed suit in federal court in New York to force Apple to modify a proposal on its proxy, which Greenlight believes does not conform to regulatory rules.

Greenlight said it is opposed to the proposal, No. 2 on Apple's proxy, which the firm said would remove Apple's ability to issue preferred stock from the company's charter.

In a filing with the U.S. Securities and Exchange Commission, Greenlight said it was "dissatisfied with Apple's capital allocation strategy."

Apple could not be immediately reached for comment.

(Reporting By Ben Berkowitz; Editing by Gerald E. McCormick)