Cryptocurrencies that seemed to be defying gravity just weeks ago came back down to earth with a bump Wednesday after a roller-coaster ride that could undermine their potential as mainstream investments.

The two main digital currencies, bitcoin and ether, fell as much as 30% and 45% respectively, but significantly pared losses after two of their biggest backers — Tesla Inc. chief Elon Musk and Ark Invest's Chief Executive Cathie Wood — indicated their support for bitcoin.

While many analysts thought the explosion in cryptocurrency interest this year was not sustainable, the trigger for the shake-out was China's move Tuesday to ban financial and payment institutions from providing cryptocurrency services. It also warned investors against speculative cryptocurrency trading.