I still dont know why bittrex or bitfinex wouldnt add a coin like this. The volume there would make this thing popout. Many investors dont even know about sonm. They will see it when it reaches big exchanges.
This has been discussed a few times already. I think main reason behind it is because of it being considered a financial token that pays dividends, SONM needs to prove Bittrex it doesn't qualify as one.
In the last weeks Bittrex probably has other problems than new coins to list, they just can not cope with the load. Hopefully they get this quickly under control.