Cryptocurrencies like bitcoin have lost over half their value so far this year, and more than that since late last year. These virtual currencies have crashed before, but this time they seem in no hurry to gain back lost ground, largely because recent evidence has revealed problems with the new technology.

In one recent study, a team of academic researchers said that market manipulation might have been behind bitcoin's steep increase in value last year. And a recent report by the New York attorney-general's office found substantial risk that consumers who invested in cryptocurrency could lose access to it, either temporarily or permanently, if there were problems at their exchange.