Cryptocurrency markets, after months of relative calm, are melting down all over again. Bitcoin crashed through its longtime floor of $6,000 and digital tokens of all types fell more than 10% in the past week.
The one exception has been so-called stablecoins, virtual currencies designed to maintain a fixed value of $1. In theory, they should be a safe haven from the larger crypto carnage. But will they hold up?
So far, the stablecoin situation has been reassuring. Three of the biggest--