A digital token debuted by President-elect Donald Trump has rattled the cryptocurrency market, attracting billions of dollars of trading volume while stoking concerns about conflicts of interest.

“It’s absolutely preposterous that he would do this,” said Nic Carter, founding partner at the crypto investment firm Castle Island Ventures who describes himself as an “avowed and explicit” Trump supporter. “They’re plumbing new depths of idiocy with the memecoin launch.”