Not sure why they keep doing it has happened to CINNI, WC and BLU at times when all coins where in pump stages.
that sounds like someone making money off of our money.. not sure if I like that.
Give Atomic a try if you are concerned about this, its the only exchange in currently in existence that has taken the extra steps to give traders the confidence that it does not happen and their coins and safe and securely stored. They have a publicly viewable liquidity page to backup their claims of not being a fractional reserve something that none of the other exchanges (Cryptsy, Mintpal, Polo) have done or are likely to provide, page is updated automatically every few hours so it is easy to see how it changes after making a deposit/withdrawal the increase/decrease in the total amount of coins held by exchange.
There is also no delay on withdrawals and Atomic does not overcharge/take profit on withdrawals, you will pay only 0.005 CINNI /withdrawal (on Cryptsy its 0.1 CINNI, Bittrex 0.2 CINNI, Mint 0.020000 CINNI)
If you believe CINNI is going to be worth more as i do, then this is alot of extra CINNI some of these exchanges are taking from you, its equal to or more then what a small stakeholder would be receiving in PoS
Mintpal is my favorite exchange. Finally dropped cryptsy a few weeks ago