Don't think it was an exchange.
Those were 70000 coins which were idle for almost 2 years.
Equals around 70000 * 2 * 365 = 51100000
Explains the days destroyed exactly
Holy cow, we haven't seen that since December of last year. Are there actually people waiting for something like this to happen in order to sell their coins as soon as the transaction hits the chain? I will always be really afraid that those coins will be dumped at spot price.