Dear friend, you can try hive-engine DEX exchange. It lists steem (but be careful with SBD, as its value is utterly reduced there). You can invest in steem there, but the steem there cannot be transferred to steemit (you can easily transfer from steemit to hive-engine DEX, but not the other way round, as steemit doesn't list a specific steem address). Unfortunately, this is my only tip because since the first of January I can't bump into any international CEX cause the regulation laws in my country.