Why not? nothing prevents someone in an exchange to play a little with the numbers as Mr X has been doing!
Too much playing, he also send some tips to people in the forum. So I guess Max is still the best guess.
edit: we should see if it is bitfinex in the next days, they would move some coins
Yeah, the tips are a bit inconsistent with the Bitfinex theory. Unless they wanted to play with us so we would speak about them, before we know it's them and after. Marketing expenses?

You are right, we should know soon. Or not, they haven't said a word officially.