The digital currency has now fallen by about 80% since peaking near $20,000 late last year.

Many speculators have fled the market, as shown by falling trading volumes. And a split this month in a smaller currency called Bitcoin Cash has created tensions. The prospect of large investors selling bitcoin to cover the risks of a fall in the value of their Bitcoin Cash holdings has hurt sentiment.

Now, another worry has emerged: Cryptocurrency miners, the outfits that solve complex equations to generate new digital coins, seem to be losing interest. The amount of computing effort expended by miners, known as the hash rate, has started falling.