Assuming someone decides to dump 18M ETH, or any other huge amount of coins, it's reasonable to assume that the coins should not be stored in the exchange for too long before the sell.
With transactions being transparent, could it not be possible to monitor ledgers for huge deposits and act accordingly, i.e. sell your coins quickly?
And if so, how difficult is it to automate that kind of monitoring?
Someone that wants to sell 20% of coin supply will not dump it but sell over longer period of time most likely will take months fro something like that. Altho high volume days are perfect for selling and such days were in last weeks. So perfect time to do it now since you would not need months for this but only weeks.