Elon Musks assets in the United States, including cash and stocks, reached a value of $500.1 billion at the close of trading.
It is equivalent to approximately 73 trillion yen in Japanese currency.
He is the richest person in the world.
Mr. Musk holds shares in companies such as Tesla, an electric vehicle company, and SpaceX, a space development company.
That day, Teslas stock price went up.
According to Forbes magazine, which ranks wealthy individuals, Mr. Musk may become the first person in the world to have assets exceeding one trillion dollars in about the next ten years.