it depends who the person owning that 18 million ETH tokens is!
- an imaginary person: obviously no effect
- a whale who is not connected to ethereum foundation and Vitalik: price can take a hit but those guys have a lot more money to put up buy walls that one whale can do nothing.
- the ethereum foundation and Vitalik themselves: price will tank hard and there is nothing stopping it because the only one that was preventing crashes so far with their fake-whaly-buy-walls are selling themselves now.
so figure out who the whale is and you get your answer.
its also possible that the 18M wall didnt have the desired effect of sending the price moving downwards.
if you look at the Polo 24hr chart set to 30 min for 12th June, you can see price flat-lined against the wall, but pressure was clearly on the upside and increasing, so it would have chewed through the wall eventually and the whale would have then had no Eth left. it was hardly bouncing down from it at all, but rather increased. so... possibly they pulled it out because it didnt have the desired effect, or even that another whale started pounding into the 18M wall in response. battle of the titans, we are just pawns in their game.
market depth also shows a lot more buyers weight than sellers. Eth is motoring right now.