USDT, the stablecoin issued by Tether Holdings Ltd., isn’t the most valuable cryptocurrency or the most likely to make you rich. Tether simply promises that if you give it $1, it’ll give you a coin that will almost always be worth $1. That dull utility has made it the most widely traded digital token in crypto. It’s also become a focus of concern in the wake of the collapse of the FTX exchange, whose knock-on effects continue to reverberate throughout the sector. If USDT stumbles, the risk of broader turmoil across already troubled crypto markets could rise significantly.

It’s a stablecoin, a category of cryptoassets that is designed to always be worth a set value, typically $1. That’s in contrast to most cryptocurrencies, which can experience big swings. Most stablecoins maintain their peg by promising to hold an equivalent value of funds in reserve as collateral to match the coins sold. For stablecoins backed by fiat currency like USDT, the majority of that collateral pile is typically held as a mix of cash and highly liquid cash equivalents.