According to a company announcement Bittrex will remove access to certain markets for U.S. users starting June 21, 2019. Markets for the 32 tokens, including $ADT, $GO, $MFT, $DNT, $GTO, $QTUM, $ENG, $NMR, $STORJ, $BLOCK, $FCT, and $STORM, will continue to be open for non-U.S. users on Bittrex International.