The unnamed firms must shut down because they lack securities registration, according to an order issued by state Attorney General Letitia James. Her office asked three other cryptocurrency-related companies to submit detailed explanations of their business models.

Bill Demchak, whose company plans to allow crypto trading through a mobile app, nonetheless expressed concern that digital currencies pegged to the dollar could affect central banks’ ability to control the money supply.

Tether will pay $41 million to settle allegations it lied in claiming its digital tokens were fully backed by fiat currencies, putting a major compliance headache behind the world’s biggest issuer of stablecoins even as regulatory scrutiny intensifies.

A central bank digital currency based on the U.S. dollar could pull deposits from banks, and it might crowd out innovative private-sector products.

The cryptocurrency exchange, which has been embroiled in a dispute with the Securities and Exchange Commission, says the federal government should create a stand-alone body to supervise the marketplace for digital assets.

After extending its deadline for request for comment on cryptocurrency by a month, the National Credit Union Administration heard from credit unions and other organizations that want clarity on the boundaries the agency plans to set.

The cryptocurrency market is double the size of the subprime debt in the U.S. on the eve of the financial crisis and poses a threat unless urgently regulated, the Bank of England said.