An article from Bloomberg suggests Bitfinex and Tether got Subpoenaed by CFTC. According to the article, this is linked to the Audit that got cancelled by Tether, and the fact that they wont disclose the name of the banks they are working with.
Read further here: https://www.bloomberg.com/news/articles/2018-01-30/crypto-exchange-bitfinex-tether-said-to-get-subpoenaed-by-cftc
Brace yourselves, winter is coming.
Krypt0man