There are quite a few that are , Glowshares, nanite, bitsharesx . and a few more.

If they were buying coins up it would show in the volumes, the market being unable to perform trades doesn't benefit anyone even bittrex .

They seem pretty honest compared to other coins, Like mintpal you could see the accumulation of surprise added coins, hours before they were released on their exchange. But if bittrex can't buy them as well, it's almost impossible they are accumulating , especially with the low order book on cryptsy