According to a report in the Wall Street Journal on Friday, which drew upon excerpts from a forthcoming biography of billionaire automaker Elon Musk that will be released later this month, Musk has been financing the development of the meme-based cryptocurrency Dogecoin, in addition to his duties as the owner of Tesla, SpaceX and the social media company X, formerly known as Twitter.

The Wall Street Journal article reveals that as he has been openly promoting Dogecoin on his Twitter account for years, he has also secretly been invested in it. The report also says that prior to his acquisition of Twitter, the billionaire had been considering creating a blockchain-based social media platform, which could have used Dogecoin as a payment system.

Quoting the biography, the article says, “After lunch, he sent [his brother] Kimbal a few texts fleshing out the idea for “a blockchain social media system that does both payments and short text messages like Twitter.”

The excerpt, describing the days just before Musk made his official bid for acquiring Twitter, noted that Musk indicated that while he found the idea of creating a brand new social media platform alluring, he ultimately decided to purchase Twitter and adapt it to his  vision because it already possessed a user base he could rely on.

Although Musk has never been shy about his public support for Dogecoin, having repeatedly tweeted his support for the meme-based cryptocurrency and noting he owns some coins, it has never been revealed before that he had secretly financed its development.

Although it would later subside, the release of the article prompted an immediate surge in the value of Dogecoin. Dogecoin, with a market capitalization of about $8.9 billion, is presently trading at $0.06, according to Coindesk, down roughly 9.41% for the year.