The head of the U.K.'s financial watchdog singled out an Instagram ad posted by Kim Kardashian, that promoted Ethereum Max, in a speech warning of the risks of "speculative" cryptocurrency tokens. 

Charles Randell, chair of the U.K.'s Financial Conduct Authority, said in a speech Monday that Kardashian had asked her more than 250 million Instagram followers to "speculate on crypto tokens by 'joining the Ethereum Max Community'."