Elon Musk’s fortune falls below $1 trillion. Elon Musk’s net worth has fallen by $28.6 billion to an estimated $977.2 billion after shares of SpaceX declined by more than 3% following the opening of trading on October 13, according to Forbes magazine. The decline pushed Musk’s fortune below the $1 trillion mark, ending his latest brief spell as the world’s first trillionaire.