not sure who would keep 8 million on bitstamp.
Seriously, anyone with that amount of money should
not keep it on any exchange, no matter how reputable it may be.
And yeah, I'd like to see some proof of this myself--but I don't think this is all that important in any case. Somebody with deep pockets might be
moving their purchase to a secure wallet--smart move--or it could be any number of other things. But this isn't going to affect the price of bitcoin, and I'm not sure it really means anything.
it is just not possible for this amount be a "purchase" because you simply can not transfer $8 million (the fiat not equivalent) from your bank to a bitcoin exchange. the bank simply won't allow it. they are closing down accounts for a lot less values such as a couple of thousand dollars!