The fact that the person is moving 8,000 BTC to an exchange could also be that they are seeking to diversify into other assets as most trading pairs use BTC. A person or entity holding that much BTC would normally use a OTC firm to sell that amount of BTC if they are smart. Remember, if they dump all that into the market via exchanges, the rest of their BTC holdings will take a hit and that represents 90% of their position.