Boston Fed President Eric Rosengren lists tether (USDT-USD) among "financial stability challenges" that the Federal Reserve is keeping an eye on, according to a presentation he gave on Friday."The reason I talked about Tether and stablecoins is if you look at their portfolio, it basically looks like a portfolio of a prime money market fund but maybe riskier," Rosengren said, according to Coindesk.That Rosengren pointed specifically to tether is seen as significant."What's interesting is [Fed governor Lael] Branard and then [Chairman Jerome] Powell started talking 'stablecoins.' But now Rosengren talks 'tether' by name. That's an escalation," Caitlin Long, the founder and CEO of Avanti Financial in Wyoming and a long-time bitcoin supporter, told Coindesk.Of course, the price of tether doesn't really change as it's pegged to $1.As for other cryptocurrencies, bitcoin (BTC-USD) is up ~4% over the past 24 hours, ether (ETH-USD) gains 13% to ~$2,081,Binance coin rises 5.3% to $292 even after a U.K. regulator