Most major U.S. credit card issuers have now banned the use of their cards to buy Bitcoin or other digital currencies, in a move intended to decrease both financial and legal risk.
Citigroup also says it is halting cryptocurrency purchases on credit, and Capital One and Discover had already enacted their own bans. That means all of the top five credit card issuers have announced or implemented bans.
The moves are above all in the banks’ self-interest. As Fortune previously reported, the mania surrounding cryptocurrency late last year appears to have motivated many retail investors to use credit cards as leveraging tools, buying more cryptocurrency than they could afford. With Bitcoin down roughly 50% from December highs, many of those investors are likely underwater right now, and may not be able to pay off their initial Bitcoin purchases soon, if ever.
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Further, as Bloomberg points out, banks may be responsible for monitoring customers’ behavior to prevent money laundering after they make a credit-backed Bitcoin purchase, a tough standard for them to comply with.
The bans — or more to the point, the news of the bans — may exacerbate ongoing declines in cryptocurrency prices. After a hefty bounce Saturday morning, crypto markets broadly retreated on Sunday. Bitcoin is now trading at around $8,500 from a December high near $20,000.
In the longer term, however, tighter cryptocurrency investment controls, whether from regulators or lenders, seem likely to help mitigate the consequences of both hype and scams. For much of 2017, those threatened to overshadow the underlying promise of blockchain technology, which is still in the very early stages of evolution.