Tesla (NASDAQ:TSLA) chief executive officer (CEO) Elon Musk donated a total of 5,044,000 shares in the electric vehicle maker to a charity in November of last year, marking one of the largest charitable gifts ever made.

The donation was worth $5.74 billion U.S., based on the closing price of Tesla shares on the five days in November that the stock awards were made. The name of the charity that received the Tesla stock has not been disclosed.

The donation came as Musk sold $16.4 billion U.S. worth of Tesla shares after polling Twitter (MYSE:TWTR) users about offloading 10% of his stake in the electric-car maker in early November. Musk said on Twitter that he would pay more than $11 billion U.S. in taxes in 2021 due to his exercise of stock options set to expire this year.

Analysts have said there would be a tax benefit for Musk potentially gifting Tesla stock, since shares donated to charity are not subject to capital gains taxes, as they would be if sold for a profit.

Regardless, the donation ranks Musk as America’s second-biggest charitable donor after Bill Gates and Melinda French Gates, data from the Chronicle of Philanthropy shows.

Musk has so far donated less than 1% of his net worth to charity, whereas Warren Buffett and George Soros have each given away more than 20% of their personal wealth, according to business magazine Forbes.

Musk is president of the “Musk Foundation,” offering grants for the “development of safe artificial intelligence to benefit humanity” among other causes, according to its website. Last year, Musk and the foundation offered $100 million U.S. in prizes to those who can come up with a technology to help remove carbon from the atmosphere.