Elon Musk pledges to give a SpaceX share to every U.S. child

Elon Musk said in a social media post Monday that he plans to give one of his SpaceX shares to each child in the U.S., writing that the gift "will be the first of many."

Musk didn't specify how the shares would be distributed or other details of how the pledge might be fulfilled. 

The SpaceX CEO is the company's largest shareholder with a 10.5% stake, according to financial data firm FactSet. His stake included 4.8 billion shares of SpaceX when the company went public earlier this year, an event that briefly made Musk the world's first trillionaire. 

There are about 73 million children in the U.S., according to Census Bureau data.

Musk, the world's richest person, is currently worth about $904 billion, according to the Bloomberg Billionaires Index.

—This is breaking news and will be updated.