The battle over Elon Musk's pay package is a showdown between his army of supporters and institutional investors

• Tesla is preparing for a showdown between some big investment firms and individual shareholders on June 13.
• Several institutional investors have indicated they plan to vote against Elon Musk's pay plan.
• Retail investors, who hold 44% of Tesla stock, could sway the vote.

Tesla is setting the stage for a battle between some vocal institutional investors and some of Elon Musk's biggest supporters.