Poloniex has stopped US customers from buying and selling nine potentially non-regulated tokens.
Source: https://www.coindesk.com/polinex-fearing-regulatory-backlash-prevents-sale-of-9-crypto-assets-in-us
Poloniex, Fearing Regulatory Backlash, Prevents Sale of 9 Crypto Assets In US
May 16, 2019
CoinDesk