Cryptocurrencies have had an exceptional year, reaching a combined value of more than USD 3 trillion (2.2 trillion pounds) for the first time in November. The market seems to have benefited from the public having time on their hands during pandemic lockdowns. Also, large investment funds and banks have stepped in, not least with the recent launch of the first bitcoin-backed ETF – a listed fund that makes it easier for more investors to get exposure to this asset class.

Alongside this has been an explosive rise in the value of stablecoins like tether, USDC, and Binance USD. Like other cryptocurrencies, stablecoins move around on the same online ledger technology known as blockchains. The difference is that their value is pegged 1:1 to a financial asset outside the world of crypto, usually the US dollar.

Stablecoins enable investors to keep money in their digital wallets that are less volatile than bitcoin, giving them one less reason to need a bank account. For a whole movement that is about a declaration of independence from banks and other centralized financial providers, stablecoins help to facilitate that. And since the rest of crypto tends to go up and down together, investors can protect themselves better in a falling market by moving money into stablecoins than, say, selling their ether for bitcoin.

A substantial proportion of buying and selling of crypto is done using stablecoins. They are particularly useful for trading on exchanges like Uniswap where there is no single company in control and no option to use fiat currencies. The total dollar value of stablecoins has shot up from the low USD 20 billion a year ago to USD 139 billion today. In one sense this is a sign that the cryptocurrency market is maturing, but it also has regulators worried about the risks that stablecoins could pose to the financial system. So what's the problem and what can be done about it? Initially introduced in the mid-2010s, stablecoins are centralized operations – in other words, someone is in control of them. Tether is ultimately controlled by the owners of the crypto exchange Bitfinex, which is based in the British Virgin Islands. USDC is owned by an American consortium consisting of payments provider Circle, bitcoin miner Bitmain and crypto exchange Coinbase. Binance USD is owned by Binance, another crypto exchange, which is headquartered in the Cayman Islands.

There is a philosophical contradiction between the decentralized ideal of cryptocurrencies and the fact that such an important part of the market is centralized. But also, there are serious questions about whether these organizations hold enough financial reserves to be able to maintain the 1:1 fiat ratios of their stablecoins in the event of a crisis.