Musk is already the world’s wealthiest person, with a net worth of about $473 billion, according to the Bloomberg Billionaires Index.

Shareholders approved a plan to grant Mr. Musk shares worth nearly $1 trillion if he meets ambitious goals, including vastly expanding the company’s stock market valuation.

The decision, experts say, amounts to a referendum on whether traditional corporate-governance rules apply to the world's richest man.