Buffett’s net worth dropped earlier this week when he donated $2.9 billion in Berkshire Hathaway stock to charity, the report added.

Tesla’s shares have surged 500% over the past year as the company increased sales of its Model 3 sedan.

The blistering rally also puts Musk in reach of a payday potentially worth $1.8 billion, his second jackpot from the electric car maker in about two months.

The stock is up about 38% since the close on July 1, a day before the company reported its quarterly delivery numbers.