[ringaroundthetx]

People don't know Vitalik's addresses. People estimate his worth and have no idea how much he kept or sold after the ICO in 2014 or at low prices in Ethereum.

Also, Ethereum won't mix inputs from different sending addresses, so it would have to be done in multiple transactions if he has multiple addresses. This would be indistinct from all the other transactions on the network.

OTC markets would try to price his assets at a lower value, and thats where you negotiate, and find counterparties yourself. If you know of several hedge funds that want to BUY ethereum without moving the markets UP, then you can sell straight to them, and tell the OTC trader that they won't get any volume and then you'll get a better price.