The battle between Apple and David Einhorn got more heated after the fund manager responded to comments made by CEO Tim Cook early Tuesday.
Apple's Cook called Einhorn's lawsuit against the tech giant a "silly sideshow" at the Goldman Sachs Technology and Internet Conference and Einhorn's firm, Greenlight Capital, quickly fired back.
(Read More: Apple's Cook Calls Einhorn Lawsuit 'Silly Sideshow' )
"If Apple thinks the lawsuit is a waste of resources it could simply end the matter by complying with existing law and filing a new proxy that unbundles the proposed changes to the charter so that shareholders can express their views on each matter separately," a Greenlight spokesperson said in a statement Tuesday.