I have no clue if this is the case but I have a sneaky suspicion CCEX might be the big seller on SX - as they had about 20 mil in the wallet.
Ouch I really hope that is not the case, but it did seem that C-CEX was doing an exit scam of some sort...
Well, yes, that's scathing, but from their perspective, they had a 24 million BBP 'house balance'. They posted a notice that they will be leaving by June 1st for re-organization, that everyone should withdraw the coins (as after this date, withdrawals will not be possible). Whatever is left in the house balance after that date, they consider to be their assets.
So from their perspective they are probably liquidating and keeping the BTC.
But, know that I myself in no way shape or form would ever do this to anyone. If I had an exchange I would allow 6 months to withdraw and I would be sending daily e-mails saying come and get your balance as these aren't my funds.