Does it matter who or what placed the order? I see it as some sort of price manipulation by someone or some group. If they are serious in selling that much, they could do it quietly in trenches.
I keep hearing (well, actually: reading) that reasoning, but it just shows a fundamental lack of understanding in short to mid term trading, imo.
There was a clear and expected bounce from 275 forming. A large player who really *wanted* to get out, fast, and at the best possible price, could have done worse than putting it up as a big wall. Maybe there would have been more sophisticated ways (e.g. splitting it up over exchanges), selling it in smaller chunks, but let's be real as well: 9M USD worth of Bitcoin were sold with zero slippage, in a rather illiquid market. That's not half bad.
Now, if we assume that price will go to the moon next, sure, it was a bad decision. But at that time we're not arguing anymore whether the whale made the right decision in how he sold, but whether his outlook into the near future or our own is correct.
tl;dr Sell wall into rebound from capitulation bottom isn't really the dumbest way to get rid of large amount of coins,
if you want to get rid of them.