There is no real possibility of knowing if this adress belongs to a whale or not. My theory : the dude who bought 400Musd in bitcoin was a whale who participated at the previous bullrun and the previous dump. He's just taking back some cheap bitcoin he sold  earlier for profit.
The fact that bitcoin price isn't regulated allow this kind of stuff.

Of maybe he's just some rich guy who got into my new favorite website http://www.isittimetobuybitcoin.org/