It looks like TNT tokens are not security tokens, but utility. This means all US exchanges (bittrex, polo, kraken) may add it with no fear of regulators (SEC etc)

https://blog.zeppelin.solutions/tierion-network-token-audit-163850fd1787

I'm holding at least before price will rich 1$ per 1 TNT


ps: And another one small Chinese exchange https://www.coinvc.com/market/trade/cny_tnt