It amazes me a lot that no one has mentioned this yet. It is the first Crypto Exchange to delist completely anonymous cryptocoins such as Monero, Dash and Zcash.
The authorities simply demand transparency in the future. In addition, all Americans with a holdings over 10K US $ in crypto must verify their account and pay taxes.
https://www.coindesk.com/bittrex-to-delist-privacy-coins-monero-dash-and-zcash