Tether, Facebook Coin Spur Worry at Yellenâs Closed-Door Meeting Jul 28 2021, 1:43 AM July 27 2021, 9:54 PM July 28 2021, 1:43 AM (Bloomberg) -- Tether and the Facebook Inc.-backed Diem token were a main focus of a recent meeting U.S. regulators held on the financial risks posed by stablecoins, a fast-growing corner of the cryptocurrency industry, said people familiar with the matter. (Bloomberg) -- Tether and the Facebook Inc.-backed Diem token were a main focus of a recent meeting U.S. regulators held on the financial risks posed by stablecoins, a fast-growing corner of the cryptocurrency industry, said people familiar with the matter.