In November of 2011 Mt. Gox demonstrated control of 500k BTC. I followed the 500,000 BTC for a bit beginning at https://blockchain.info/tx/b269bf1b82dae8a61f7f91dbf7a9d807e... . The coins move around and small amounts are sent away, but the majority ends up back in Mt. Gox's main (hot) wallet. This repeats a few times until the majority is paid back to the main Mt.Gox address. Here is the transaction where it starts…
Can anybody follow one of these "branches" until the very last known transaction on the blockchain? Would that clear anything up?
Here is a some background information at Let's Talk Bitcoin:
http://letstalkbitcoin.com/the-ghost-in-the-machine-at-mtgox