On the birth of his daughter, Zuck does something incredible. From this SEC filing from Facebook
On December 1, 2015, our Founder, Chairman and CEO, Mark Zuckerberg, announced that , during his lifetime, he will gift or otherwise direct substantially all of his shares of Facebook stock, or the net after-tax proceeds from sales of such shares, to further the mission of advancing human potential and promoting equality by means of philanthropic, public advocacy, and other activities for the public good. For this purpose, Mr. Zuckerberg has established a new entity, the Chan Zuckerberg Initiative, LLC, and he will control the voting and disposition of any shares held by such entity. He has informed us that he plans to sell or gift no more than $1 billion of Facebook stock each year for the next three years and that he intends to retain his majority voting position in our stock for the foreseeable future. Any sale of shares by Mr. Zuckerberg will be conducted pursuant to a trading plan established pursuant to Rule 10b5-1 under the Securities Exchange Act of 1934, as amended (the "Exchange Act"). Sales and gifts of shares by Mr. Zuckerberg will be disclosed publicly in accordance with the rules established by the U.S. Securities and Exchange Commission under Section 16 of the Exchange Act. As of the date of this filing, Mr. Zuckerberg beneficially owns approximately 4 million shares of Class A common stock and approximately 419 million shares of Class B common stock.