The digital token known as Tron tumbled as much as 16% after cryptocurrency entrepreneur Justin Sun postponed his charity lunch meeting with billionaire Warren Buffett citing a bout of kidney stones.

Buffett and 29-year-old Sun agreed to reschedule, according to a tweet Monday from his Tron Foundation. The lunch had been set for Thursday in San Francisco.

Sun bid a record $4.57 million this year to win the chance to dine with Buffett as part of his annual charity lunch auction. Sun, who launched Tronix in 2017, said in June that he was hoping to educate Buffett, a self-professed cryptocurrency critic, on the benefits of crypto and the underlying technology, blockchain.

The postponement came only hours after Sun tweeted invitations to other crypto boosters to join him, spurring speculation there may be other reasons for the decision. Sun denied media reports that he was involved in illegal fundraising and money laundering, according to China’s state-run Global Times.

This article was provided by Bloomberg News.