The purpose of the change is to "ensure that we will not remain a founder-controlled company after we cease to be a founder-led company," according to a proxy filing.
Zuckerberg owns "about 4 million Class A shares and about 419 million Class B shares, collectively representing about 53.8 percent of total outstanding voting power," according to Reuters.
Business Insider reported the CEO controlled 60 percent of Facebook's voting power, meaning a June 20 vote on the new provision by shareholders is "largely a formality."
So how did Zuckerberg come to have so much control to begin with? A 2015 post on Inc.com by Quora, written by Storm Ventures partner Jason M. Lemkin explains: Zuckerberg was able to retain ownership of a large portion of the company by skipping a venture capital round.
"Because it's less how much you raise that creates dilution--it's how many times you raise," Lemkin wrote. "Because each time, everyone needs to be able to buy a material amount of your company."