The largest digital currency fell as much as 6.2 percent to $5,887 as of 10:44 a.m. in Hong Kong, the lowest level since June, according to Bloomberg composite pricing. Ether sank 12 percent, while all but one of the 100 biggest cryptocurrencies tracked by Coinmarketcap.com recorded declines over the past 24 hours. The total market capitalization of cryptocurrencies dropped to $190 billion, from a peak of around $835 billion in January.

While Bitcoin and its peers rallied in July on hopes that a Bitcoin-backed exchange-traded fund would attract new investors to the world of virtual currencies, U.S. regulators have yet to sign off on multiple proposals for such a product. The letdown has coincided with growing concern that entrepreneurs who raised crypto-denominated funds via initial coin offerings are now cashing out of coins such as Ether.

Bitcoin has now dropped about 23 percent in August, extending its retreat this year to 58 percent.