US billionaire Warren Buffett has ruled out a foray into cryptocurrencies, warning that the Bitcoin boom will "come to a bad ending".

JP Morgan chief executive Jamie Dimon has backtracked on criticism of Bitcoin, saying he regrets calling the cryptocurrency a "fraud".

Jamie Dimon, chairman and CEO of JPMorgan Chase, spent $26.6m (€23.66m) to buy shares of his bank on Thursday after they tumbled to the lowest price in more than two years. Yesterday, the stock surged 8%, the most in more than four years.