Masayoshi Son, the billionaire founder of SoftBank Group Corp., made a huge personal bet on bitcoin just as prices for the digital currency peaked, losing more than $130 million when he cashed out, the Wall Street Journal reported Tuesday, quoting people familiar with the matter.

Son, who launched the world’s biggest venture capital fund on the strength of his long-term investment acumen, made the transaction at the recommendation of a well-known bitcoin booster, whose investment firm SoftBank bought in 2017, it said.

The investment came at the peak of the bitcoin frenzy in late 2017 after the digital currency had already risen more than tenfold that year. The exact size of the bet couldn’t be determined, but bitcoin peaked at nearly $20,000 in mid-December 2017 and Son sold in early 2018 after bitcoin had plummeted, the paper said.

Bitcoin traded at around $5,300 (about ¥592,600) on Monday.

A SoftBank spokesman reportedly declined to comment on Son’s behalf.

Under Son’s direction, SoftBank has evolved into a global telecommunications and internet conglomerate, and his penchant for pursuing out-of-the-box ideas appears as strong as ever as he looks to craft a connected future run by computers far more “intelligent” than humans.

Now 61, Son is already a legend in Japan, where comic books depict the rags-to-riches story of a third-generation Korean-Japanese from a poor neighborhood who climbed his way up to become one of the nation’s richest men.